BÈ‚ÏÈÔÁÚ·ÊÈ΋ AÓ·ÛÎfiËÛË Literature Review ∑ÈÚÎÔÓ›·: ™‡Á¯ÚÔÓ˜ ·fi„ÂȘ ÂÓfi˜ ÔÏ˘Û˘˙ËÙË̤ÓÔ˘ ˘ÏÈÎÔ‡. ¢ÔÌ‹, ÂÊ·ÚÌÔÁ¤˜ Î·È ÎÏÈÓÈÎÔ› ÚÔ‚ÏËÌ·ÙÈÛÌÔ› ∂. Δ˙·Ó·Î¿Î˘*, π. Δ˙Ô‡Ù˙·˜**, ∂. ∫ÔÓÙÔÓ·Û¿ÎË*** Zirconia: Contemporary views of a much talked material: Structure, applications and clinical considerations E. Tzanakakis*, I. Tzoutzas**, E. Kontonasaki*** ¶EPI§HæH SUMMARY T· ÙÂÏÂ˘Ù·›· ¯ÚfiÓÈ·, Â˘Ú‡Ù·ÙË ı¤ÛË ÛÙËÓ Â·ÓÔÚıˆÙÈ΋ Ô‰ÔÓÙÈ·ÙÚÈ΋ η٤¯Ô˘Ó Ù· ÎÂÚ·ÌÈο ˙ÈÚÎÔÓ›·˜. H ˙ÈÚÎÔÓ›· (ηı·Úfi ÔÍ›‰ÈÔ ZrO2), ÚÔ¤Ú¯ÂÙ·È ·fi ÙÔ˘˜ ÔχÙÈÌÔ˘˜ Ï›ıÔ˘˜ ˙ÈÚÎÔÓ›ÙË Î·È ‚·‰‰ÂÏÂ˚ÙË. H ¯Ú‹ÛË Ù˘ ˙ÈÚÎÔÓ›·˜ ÛÙȘ ‚ÈÔ˚·ÙÚÈΤ˜ ÂÊ·ÚÌÔÁ¤˜ ÍÂΛÓËÛ ˆ˜ ˘ÏÈÎfi ÛÙËÓ ÔÏÈ΋ ·ÚıÚÔÏ·ÛÙÈ΋ ÎÂÊ·Ï‹˜ ÌËÚÈ·›Ô˘ ÔÛÙÔ‡. H ˙ÈÚÎÔÓ›· ÎÚ˘ÛÙ·ÏÏÒÓÂÙ·È Û ΢‚È΋, ÙÂÙÚ·ÁˆÓÈ΋ Î·È ÌÔÓÔÎÏÈÓ‹ ÌÔÚÊ‹ ·Ó¿ÏÔÁ· Ì ÙË ıÂÚÌÔÎÚ·Û›·. °È· ÙËÓ ÂÍ·ÛÊ¿ÏÈÛË ÙˆÓ ‚¤ÏÙÈÛÙˆÓ Ì˯·ÓÈÎÒÓ È‰ÈÔًوÓ, ··ÈÙÂ›Ù·È Ë ÛÙ·ıÂÚÔÔ›ËÛË Ù˘ ÙÂÙÚ·ÁˆÓÈ΋˜ Ê¿Û˘ Û ıÂÚÌÔÎÚ·Û›· ‰ˆÌ·Ù›Ô˘, Ë ÔÔ›· Ú·ÁÌ·ÙÔÔÈÂ›Ù·È Ì ‰È¿ÊÔÚ· ÔÍ›‰È· .¯. ˘ÙÙÚ›Ô˘ Î·È ‰ËÌËÙÚ›Ô˘ (Y2O3, CeO2). ™ÙËÓ O‰ÔÓÙÈ·ÙÚÈ΋ ¯ÚËÛÈÌÔÔÈÔ‡ÓÙ·È ÙÚÂȘ Ù‡ÔÈ ˙ÈÚÎÔÓ›·˜, Ë Ï‹Úˆ˜ ÛÙ·ıÂÚÔÔÈË̤ÓË ÙÂÙÚ·ÁˆÓÈ΋ ˙ÈÚÎÔÓ›·, Ë ÌÂÚÈÎÒ˜ ÛÙ·ıÂÚÔÔÈË̤ÓË ˙ÈÚÎÔÓ›· Î·È Ë ·ÏÔ˘Ì›Ó· ÂÓÈÛ¯˘Ì¤ÓË Ì ˙ÈÚÎÔÓ›·. T· ÎÂÚ·ÌÈο ÙÔ˘ ÚÒÙÔ˘ Ù‡Ô˘, ·ÚÔ˘ÛÈ¿˙Ô˘Ó ˘„ËϤ˜ Ì˯·ÓÈΤ˜ È- In recent years, zirconia ceramics hold a remarkable place in restorative dentistry. Zirconia (pure ZrO2), is derived from the gemstones zirconite and baddeleyite. The use of zirconia in biomedical applications started in total hip femoral head replacement. Zirconia crystallizes in cubic, tetragonal and monoclinic form depending on temperature. For ceramics with the optimum mechanical properties the stabilization of the tetragonal phase at room temperature is a prerequisite, and is performed with various stabilizing oxides e.g. cerium and yttrium (Y2O3, CeO2). Three types of zirconia are used in Dentistry, the fully stabilized tetragonal zirconia, the partially stabilized zirconia and the alumina -reinforced zirconia. Fully stabilized tetragonal zirconia ceramics exhibit high mechanical properties, but present two main drawbacks: uncontrolled growth of the monoclinic phase, which can lead to prema- * O‰ÔÓÙ›·ÙÚÔ˜, ¶ÚÔÛıÂÙÔÏfiÁÔ˜ À¢ μÈÔ¸ÏÈÎÒÓ ∂∫¶∞ ** O‰ÔÓÙ›·ÙÚÔ˜, ∞Ó. ∫·ıËÁËÙ‹˜ O‰ÔÓ. ÃÂÈÚÔ˘ÚÁÈ΋˜ ∂∫¶∞ *** O‰ÔÓÙ›·ÙÚÔ˜, E. K·ıËÁ‹ÙÚÈ· ¶ÚÔÛıÂÙÔÏÔÁ›·˜ ∞ΛÓËÙ˘ ¶ÚÔÛıÂÙÈ΋˜ ∞¶£ ÂÏÏËÓÈο ÛÙÔÌ·ÙÔÏÔÁÈο ¯ÚÔÓÈο 57: 101-137, 2013 ·ÚÂÏ‹ÊıË 2/1/2014 - ÂÎÚ›ıË 13/1/2014 * Prosthodontist, MSc Phd cand Biomaterials UOA ** Associate Professor Operative Dentistry UOA *** Assistant Professor AUTH Hellenic Stomatological Review 57: 101-137, 2013 paper received 2/1/2014 - accepted 13/1/2014 101 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review ‰ÈfiÙËÙ˜, Ì ‚·ÛÈÎfiÙÂÚ· ÌÂÈÔÓÂÎÙ‹Ì·Ù¿ ÙÔ˘˜ ÙË ÌË ÂÏÂÁ¯fiÌÂÓË ·Ó¿Ù˘ÍË Ù˘ ÌÔÓÔÎÏÈÓÔ‡˜ Ê¿Û˘ Ô˘ ÌÔÚ› Ó· Ô‰ËÁ‹ÛÂÈ ÙÔ ˘ÏÈÎfi Û ÚÒÈÌË ·ÛÙÔ¯›·, Î·È ÙËÓ ·˘ÍË̤ÓË ·‰È·Ê¿ÓÂÈ·. ™ÙËÓ Ô‰ÔÓÙÈ·ÙÚÈ΋ ¤¯Ô˘Ó ¯ÚËÛÈÌÔÔÈËı› ÁÈ· ÙËÓ Î·Ù·Û΢‹ ·Î›ÓËÙˆÓ ÔÏÔÎÂÚ·ÌÈÎÒÓ ÛÙÂÊ·ÓÒÓ Î·È ÁÂÊ˘ÚÒÓ, ÂÓ‰ÔÚÚÈ˙ÈÎÒÓ ·ÍfiÓˆÓ, ÁÂÊ˘ÚÒÓ ÛÙËÚÈ˙fiÌÂÓ˜ Û ¤ÓıÂÙ· ‹ Ù‡Ô˘ Maryland, ÂÌÊ˘ÙÂ˘Ì¿ÙˆÓ Î·È ÂÈÂÌÊ˘ÙÂ˘Ì·ÙÈÎÒÓ ÎÔÏÔ‚ˆÌ¿ÙˆÓ. OÈ ÚÒÙ˜ 3ÂÙ›˜ Î·È 5ÂÙ›˜ ÎÏÈÓÈΤ˜ ÌÂϤÙ˜ Â›Ó·È ÂÓı·ÚÚ˘ÓÙÈΤ˜ ÁÈ· ÙË Û˘ÌÂÚÈÊÔÚ¿ ÙÔ˘ ˘ÏÈÎÔ‡ ÛÙÔ ÛÙÔÌ·ÙÈÎfi ÂÚÈ‚¿ÏÏÔÓ, Ì ΢ڛ·Ú¯Â˜ ÂÈÏÔΤ˜ ÙËÓ ·ÔÎfiÏÏËÛË ÙˆÓ ·ÔηٷÛÙ¿ÛˆÓ, ÙËÓ ·ÔÊÏÔ›ˆÛË ÙˆÓ ÂÈÎ·Ï˘ÙÈÎÒÓ ÎÂÚ·ÌÈÎÒÓ ·ÏÏ¿ Î·È ÙË ıÚ·‡ÛË ÙˆÓ Û˘Ó‰¤ÛÌˆÓ Ì ÌÈÎÚ¤˜ ‰È·ÛÙ¿ÛÂȘ. TÔ ÁÂÁÔÓfi˜ fiÙÈ ‰ÂÓ ˘¿Ú¯Ô˘Ó Ì·ÎÚfi¯ÚÔÓ˜ ÌÂϤÙ˜ ÂÈ‚›ˆÛ˘ ÙˆÓ ·ÔηٷÛÙ¿ÛÂˆÓ ˙ÈÚÎÔÓ›·˜, ηıÈÛÙ¿ ÂÏÏÈ‹ ÙËÓ ÙÂÎÌËÚ›ˆÛË ÁÈ· ÙËÓ Î·ıÔÏÈ΋ ‹ ÌÂÚÈ΋ ·Ô‰Ô¯‹ ÙÔ˘ ˆ˜ ·ÍÈfiÈÛÙ˘ ÂÓ·ÏÏ·ÎÙÈ΋˜ χÛ˘ ÙˆÓ ÎÏ·ÛÈÎÒÓ ÌÂÙ·ÏÏÔÎÂÚ·ÌÈÎÒÓ ·ÔηٷÛÙ¿ÛˆÓ. §¤ÍÂȘ ÎÏÂȉȿ: ˙ÈÚÎÔÓ›·, ˙ÈÚÎfiÓÈÔ, ÌÔÓÔÎÏÈÓ‹˜ Ê¿ÛË, ȉÈfiÙËÙ˜, ÂÊ·ÚÌÔÁ¤˜. EI™A°ø°H TȘ ÙÂÏÂ˘Ù·›Â˜ ‰ÂηÂٛ˜ ¤¯Ô˘Ó ¤ÏıÂÈ ÛËÌ·ÓÙÈΤ˜ ·ÏÏ·Á¤˜ ÛÙÔ ¯ÒÚÔ Ù˘ Ô‰ÔÓÙÈ·ÙÚÈ΋˜ ÂÈÛÙ‹Ì˘. H ‚·ı‡ÙÂÚË ‰ÈÂÚ‡ÓËÛË Ê·ÈÓÔÌ¤ÓˆÓ Î·È Ì˯·ÓÈÛÌÒÓ Ô˘ ·ÊÔÚÔ‡Ó ÛÙË ÏÂÈÙÔ˘ÚÁ›· ÙÔ˘ ÛÙÔÌ·ÙÔÁÓ·ıÈÎÔ‡ Û˘ÛÙ‹Ì·ÙÔ˜ ¤‰ˆÛ·Ó ÒıËÛË Û ÔÏÏ¿ ÂÈÛÙËÌÔÓÈο ‰›·, ÛÙËÓ ÚfiÏË„Ë, ÛÙË ıÂڷ›· ·ÏÏ¿ Î·È ÛÙËÓ ¤ÌÊ˘ÙË ·Ó¿ÁÎË ÙÔ˘ ·ÓıÚÒÔ˘ ÁÈ· ηχÙÂÚË ·ÈÛıËÙÈ΋. ™ÙÔÓ ÙÔ̤· Ù˘ ıÂڷ›·˜, ‚·ÛÈÎfi˜ ÛÙfi¯Ô˜ Ù˘ Ô‰ÔÓÙÈ·ÙÚÈ΋˜ Â›Ó·È Ë ·ÔηٿÛÙ·ÛË Î·È Ë ‰È·Ù‹ÚËÛË ÙÔ˘ ıÂڷ¢ÙÈÎÔ‡ ·ÔÙÂϤÛÌ·ÙÔ˜. ™ÙÔ ¯ÒÚÔ ·˘Ùfi ȉȷ›ÙÂÚÔ ÚfiÏÔ Î·Ù¤¯Ô˘Ó Ù· ˘ÏÈο ·ÔηٿÛÙ·Û˘ Ù· ÔÔ›· ˆ˜ ÙÌ‹Ì· ÙˆÓ Ô‰ÔÓÙÈ·ÙÚÈÎÒÓ ‚ÈÔ¸ÏÈÎÒÓ ‚Ú›ÛÎÔÓÙ·È Û ‰È·Ú΋ ÂͤÏÈÍË Î·È ¤Ú¢ӷ. AÔÙ¤ÏÂÛÌ· ÌÂÏÂÙÒÓ Î·È Ì·ÎÚÔ¯ÚfiÓÈˆÓ ÂÈÚ·Ì¿ÙˆÓ Â›Ó·È Ô ¤ÏÂÁ¯Ô˜ Ù˘ ·ÍÈÔÈÛÙ›·˜ ÙˆÓ Ô‰ÔÓÙÈ·ÙÚÈÎÒÓ ˘ÏÈÎÒÓ. ™‹ÌÂÚ· ˘¿Ú¯Ô˘Ó ˘ÏÈο Ù· ÔÔ›· ¤‰ˆÛ·Ó ÁÈ· ÔÏÏ¿ ¯ÚfiÓÈ· ˘ËÚÂۛ˜ ÛÙËÓ Ô‰ÔÓÙÈ·ÙÚÈ΋ Î·È ÂÍ·ÎÔÏÔ˘ıÔ‡Ó Ó· ·Ú¿ÁÔÓÙ·È Î·È Ó· ıˆÚÔ‡ÓÙ·È ·ÍÈfiÈÛÙ·. ŒÓ·˜ ÌÂÁ¿ÏÔ˜ ÂÚ¢ÓËÙÈÎfi˜ ¯ÒÚÔ˜ ÂÚÈÎÏ›ÂÈ Ó¤· ˘ÏÈο Ù· ÔÔ›· Û˘ÓÙ›ıÂÓÙ·È ÛÙËÚÈ˙fiÌÂÓ· Û ˘¿Ú¯Ô˘Û˜ ‚·ÛÈΤ˜ ‰Ô̤˜ Î·È ·ÔÙÂÏÔ‡Ó ÙËÓ ÂͤÏÈÍ‹ ÙÔ˘˜, ›Ù ¤¯Ô˘Ó ‰ÔÎÈÌ·ÛÙ› Û ‰È·ÊÔÚÂÙÈΤ˜ ÂÊ·ÚÌÔÁ¤˜ ¿ÏÏˆÓ ÂÈÛÙËÌÒÓ. ŒÓ· ¯·Ú·ÎÙËÚÈÛÙÈÎfi ·Ú¿‰ÂÈÁÌ· Â›Ó·È Ù· ·ÓıÚ·ÎÔÓ‹Ì·Ù·, Ù· ÔÔ›· ¯ÚËÛÈÌÔÔÈÔ‡ÓÙ·È Û ‰È¿ÊÔÚ˜ ÂÊ·ÚÌÔÁ¤˜ ÁÈ· Ì˯·ÓÈ΋ ‹ ıÂÚÌÈ΋ ÂÓ›Û¯˘ÛË Û‡ÓıÂÙˆÓ ˘ÏÈÎÒÓ1 Î·È ÛÙËÓ ·˘ÙÔÎÈÓËÙÔ‚ÈÔÌ˯·Ó›·. ™ÙËÓ Ô‰ÔÓÙÈ·ÙÚÈ΋ ‰ÔÎÈÌ¿ÛÙËÎ·Ó Û·Ó ˘ÏÈÎfi ÚÔηٷÛ΢·ÛÌ¤ÓˆÓ ·ÍfiÓˆÓ. ™ÙÔ ¯ÒÚÔ ÙˆÓ Ó¤ˆÓ ˘ÏÈÎÒÓ Á›ÓÔÓÙ·È ÌÂϤÙ˜ ÁÈ· Ó· ÂÍ·¯ıÔ‡Ó Û˘ÌÂÚ¿ÛÌ·Ù· Û¯ÂÙÈο Ì ÙËÓ ·ÓÙÈηٿÛÙ·ÛË ‹ ÌË ·Ï·ÈÔÙ¤ÚˆÓ ˘ÏÈÎÒÓ. T· Ô‰Ô102 ture failure, and increased opacity. In dentistry they have been used for the construction of all ceramic crowns and fixed partial dentures, aesthetic posts, inlay-supported or Maryland type partial dentures, as dental implants and abutments. The first 3- and 5year clinical studies are encouraging for the behavior of the material in the oral environment, with main complications being the restoration decementation, the chipping of the ceramic veneer and the fracture of connectors with small dimensions. The fact that there are no long-term studies on the clinical survival of zirconia restorations makes incomplete the documentation of the material for its total or partial acceptance as a viable alternative to the classic metal-ceramic restorations Key Words: zirconia, zirconium, monoclinic, properties, applications. INTRODUCTION In recent decades there have been significant changes in the field of dental science. A deeper investigation of phenomena and mechanisms related to the function of the stomatognathic system promoted many scientific fields such as prevention and treatment, and satisfied the innate human need for better aesthetics. The main treatment goal in dentistry, is to restore and maintain the therapeutic effect. Under this perspective, special role for many years hold restorative materials which as part of dental biomaterials are constantly evolving. Scientific results and long-term experiments are needed to test the reliability of dental materials. Today, there are materials that have provided services for many years in dentistry and continue to be considered reliable. A large research area in dental materials includes newly synthesized materials relying on existing basic structures that consist either evolutionary products is, or existing products that have been tested in different applications. Typical examples are the carbon fibers, which are used in various applications for mechanical or thermal reinforcement composites1 and the automotive industry. In dentistry they have been used as prefabricated posts. A lot of new studies continuously provide evidence-based knowledge concerning the need for replacement of older or current materials. Dental materials follow the rules dictated by their chemical composition and differ in physical, chemical, optical and mechanical properties. The deep knowledge of materials’ properties is the most important prerequisite for their correct application. In the field of restorative dentistry ceramic materials hold important position. A basic property but at the same time disadvantage of ceramics is their brittle nature which makes them brittle when they are deformed by more than 0,1%2. This led researchers to attempt to strengthen the Hellenic Stomatological Review 57: 101-137, 2013 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review ÓÙÈ·ÙÚÈο ˘ÏÈο ·ÎÔÏÔ˘ıÔ‡Ó ÙÔ˘˜ ηÓfiÓ˜ Ô˘ ˘·ÁÔÚ‡ÂÈ Ë ¯ËÌÈ΋ ÙÔ˘˜ Û‡ÓıÂÛË Î·È ‰È·Ê¤ÚÔ˘Ó ÌÂٷ͇ ÙÔ˘˜ ÛÂ Ê˘ÛÈΤ˜, ¯ËÌÈΤ˜, ÔÙÈΤ˜ Î·È Ì˯·ÓÈΤ˜ ȉÈfiÙËÙ˜. H ‚·ıÈ¿ ÁÓÒÛË ÙˆÓ È‰ÈÔÙ‹ÙˆÓ ÙˆÓ ˘ÏÈÎÒÓ Â›Ó·È Ë ‚·ÛÈÎfiÙÂÚË ÚÔ¸fiıÂÛË ÁÈ· ÙË ÛˆÛÙ‹ ÂÊ·ÚÌÔÁ‹ ÙÔ˘˜. ™ÙÔ ¯ÒÚÔ Ù˘ ·ÓÔÚıˆÙÈ΋˜ Ô‰ÔÓÙÈ·ÙÚÈ΋˜ ÛËÌ·ÓÙÈ΋ ı¤ÛË Î·Ù¤¯ÂÈ Ë ¯Ú‹ÛË ÙˆÓ ÎÂÚ·ÌÈÎÒÓ ˘ÏÈÎÒÓ. B·ÛÈÎfi ¯·Ú·ÎÙËÚÈÛÙÈÎfi ·ÏÏ¿ Î·È ÌÂÈÔÓ¤ÎÙËÌ· ÙˆÓ ÎÂÚ·ÌÈÎÒÓ Â›Ó·È Ë „·ı˘Ú‹ ÙÔ˘˜ ʇÛË, Ô˘ Ù· ηıÈÛÙ¿ ‡ıÚ·˘ÛÙ· fiÙ·Ó ·Ú·ÌÔÚʈıÔ‡Ó Û ÔÛÔÛÙfi ÌÂÁ·Ï‡ÙÂÚÔ ÙÔ˘ 0,1%2. A˘Ùfi Ô‰‹ÁËÛ ÙÔ˘˜ ÂÚ¢ÓËÙ¤˜ ÛÙËÓ ÚÔÛ¿ıÂÈ· ÂÓ›Û¯˘Û˘ ÙˆÓ ÎÂÚ·ÌÈÎÒÓ Ì ٤ÙÔÈÔ ÙÚfiÔ ÒÛÙ ӷ ÌËÓ Ô‰ËÁÔ‡ÓÙ·È Û ıÚ·‡ÛË Î·È Ó· ‰È·ÙËÚÔ‡Ó fiϘ ÙȘ ¿ÏϘ ȉÈfiÙËÙ˜ Ô˘ Ù· ηıÈÛÙÔ‡Ó ÌÔÓ·‰Èο. H ÂͤÏÈÍË ÙˆÓ ˘ÏÈÎÒÓ ·˘ÙÒÓ ˘‹ÚÍ ڷÁ‰·›· Ù· ÙÂÏÂ˘Ù·›· ¯ÚfiÓÈ· Î·È ÙÔ ˙ËÙÔ‡ÌÂÓÔ ‹Ù·Ó Ë ·˘ÍË̤ÓË ·ÓÙÔ¯‹ Î·È Ë ‚ÂÏÙȈ̤ÓË ·ÈÛıËÙÈ΋ ÙÔ˘˜. O ÌÂÙ·ÏÏÈÎfi˜ ÛÎÂÏÂÙfi˜ ÙˆÓ ·Î›ÓËÙˆÓ ÚÔÛıÂÙÈÎÒÓ ·ÔηٷÛÙ¿ÛÂˆÓ ÂÍ·ÎÔÏÔ˘ı› ̤¯ÚÈ Û‹ÌÂÚ· Ó· ·ÔÙÂÏ› ÌÈ· ·ÍÈfiÈÛÙË Ï‡ÛË ÁÈ· ÙËÓ ˘ÔÛÙ‹ÚÈÍË ÙˆÓ ÎÂÚ·ÌÈÎÒÓ ˘ÏÈÎÒÓ. ¶·ÚfiÏ· ·˘Ù¿ Ë ·Ó¿ÁÎË ÁÈ· ηχÙÂÚË ·ÈÛıËÙÈ΋ ·fi‰ÔÛË ÙˆÓ ÎÂÚ·ÌÈÎÒÓ ·ÔηٷÛÙ¿ÛˆÓ, Ô‰‹ÁËÛ Û ÚÔÛ¿ıÂȘ ·ÓÙÈηٿÛÙ·Û˘ ÙÔ˘ ·‰È·Ê·ÓÔ‡˜ ÌÂÙ·ÏÏÈÎÔ‡ ˘Ú‹Ó·, Ô ÔÔ›Ô˜ ‰˘Û¯ÂÚ·›ÓÂÈ ÙË ¯ÚˆÌ·ÙÈ΋ ·fi‰ÔÛË ÙÔ˘ Ê˘ÛÈÎÔ‡ ‰ÔÓÙÈÔ‡. M ·˘Ùfi ÙÔ ÛÎÂÙÈÎfi ·Ó·Ù‡¯ıËÎ·Ó Ù· ÔÏÔÎÂÚ·ÌÈο Û˘ÛÙ‹Ì·Ù· ÛÙËÓ Ô‰ÔÓÙÈ·ÙÚÈ΋ Ì ÔÏϤ˜ Î·È ‰È·ÊÔÚÂÙÈΤ˜ ÚÔÛÂÁÁ›ÛÂȘ ÛÙËÓ Û‡ÛÙ·ÛË ÙˆÓ Û˘ÁÎÂÎÚÈÌ¤ÓˆÓ ˘ÏÈÎÒÓ3, 4. H ÈÔ ÚfiÛÊ·ÙË ·fi ·˘Ù¤˜ Â›Ó·È Ë ¯Ú‹ÛË ÎÂÚ·ÌÈÎÒÓ ˙ÈÚÎÔÓ›·˜ (ZrO2), ˘ÏÈÎÔ‡ Ô˘ ¤¯ÂÈ ¯ÚËÛÈÌÔÔÈËı› ÛÙË ‚ÈÔÌ˯·Ó›·, ÛÙËÓ ËÏÂÎÙÚÔÓÈ΋ ·ÏÏ¿ Î·È ÛÙÔÓ ÙÔ̤· Ù˘ È·ÙÚÈ΋˜ ˆ˜ ˘ÏÈÎfi Ù˘ ÔÚıÔ‰È΋˜5. H ˙ÈÚÎÔÓ›· Û‹ÌÂÚ· η٤¯ÂÈ È‰È·›ÙÂÚË ı¤ÛË ÛÙÔÓ ÙÔ̤· Ù˘ Ô‰ÔÓÙÈ·ÙÚÈ΋˜ ηıÒ˜ ¤¯ÂÈ ·ÍÈÔÔÈËı› ÙfiÛÔ ÛÙÔÓ ÙÔ̤· Ù˘ ·ÔηٿÛÙ·Û˘ Û ‰È¿ÊÔÚ˜ ηٷÛ΢¤˜ -΢ڛˆ˜ ˆ˜ ˘ÏÈÎfi ˘Ú‹Ó· ·Î›ÓËÙˆÓ ÔÏÔÎÂÚ·ÌÈÎÒÓ ·ÔηٷÛÙ¿ÛˆÓ-, fiÛÔ Î·È Ì ÙË ÌÔÚÊ‹ ‚ÈÔ¸ÏÈÎÔ‡ ÔÛÙÂÔÂÓۈ̷ÙÔ‡ÌÂÓˆÓ Ô‰ÔÓÙÈÎÒÓ ÂÌÊ˘ÙÂ˘Ì¿ÙˆÓ. OÈ ·ÔηٷÛÙ¿ÛÂȘ Ì ˙ÈÚÎÔÓ›· ÂÌÊ·Ó›˙ÔÓÙ·È ÛÙÔÓ Ô‰ÔÓÙÈ·ÙÚÈÎfi ¯ÒÚÔ ÌÂÙ¿ ÙÔ 2000 Ì ¢ڇÙÂÚË ·Ô‰Ô¯‹ ÌÂÙ¿ ÙÔ 20105. I™TOPIKH ANA¢POMH TÔ ˙ÈÚÎfiÓÈÔ Â›Ó·È ÁÓˆÛÙfi ˆ˜ ÔχÙÈÌÔ˜ Ï›ıÔ˜ ·fi ·Ú¯·ÈÔÙ¿ÙˆÓ ¯ÚfiÓˆÓ. TÔ Ì¤Ù·ÏÏÔ ˙ÈÚÎfiÓÈÔ Ì ·ÙÔÌÈÎfi ·ÚÈıÌfi 40, ¤¯ÂÈ ¿ÚÂÈ ÙËÓ ÔÓÔÌ·Û›· ÙÔ˘ ·fi ÙËÓ ·Ú·‚È΋ ϤÍË zargon Ô˘ ÛËÌ·›ÓÂÈ ¯Ú˘Ûfi Û ¯ÚÒÌ· Î·È ÚÔ¤Ú¯ÂÙ·È ·fi ÙȘ ÂÚÛÈΤ˜ ϤÍÂȘ zar (¯Ú˘Ûfi˜) Î·È gun (¯ÚÒÌ·). TÔ ‰ÈÔÍ›‰ÈÔ ÙÔ˘ ˙ÈÚÎÔÓ›Ô˘ (ZrO2), ÙÔ ÔÔ›Ô ÔÓÔÌ¿˙ÂÙ·È ˙ÈÚÎÔÓ›· ·Ó·Î·Ï‡ÊıËΠ·fi ÙÔÓ °ÂÚÌ·Ófi ¯ËÌÈÎfi Martin Heirich Klaproth ÙÔ 1789, Ô ÔÔ›Ô˜ ÙÔ ¯·Ú·ÎÙ‹ÚÈÛ ˆ˜ ͯˆÚÈÛÙfi ÛÙÔÈ¯Â›Ô ¯ˆÚ›˜ ·ÎfiÌË Ó· ÙÔ ¤¯ÂÈ ÛÙË ‰È¿ıÂÛ‹ ÙÔ˘ Û ηı·Ú‹ ÌÂÙ·ÏÏÈ΋ ÌÔÚÊ‹6. H ˙ÈÚÎÔÓ›· ÚԤ΢„ ·fi ÙËÓ fiÙËÛË ÔÚÈÛÌ¤ÓˆÓ ÔχÙÈÌˆÓ Ï›ıˆÓ Î·È ¯ÚËÛÈÌÔÔÈ‹ıËΠÁÈ· ÔÏÏ¿ ¯ÚfiÓÈ· Ì ÔÍ›‰È· Û¿ÓÈˆÓ Á·ÈÒÓ ˆ˜ ¯ÚˆÛÙÈÎÒÓ ÁÈ· ÙËÓ ÎÂÚ·ÌÈ΋7. ™ÙË Ê‡ÛË ˘¿Ú¯ÂÈ Û ÌÔÚÊ‹ ÂÓfi˜ Û¿ÓÈÔ˘ ÂÙÚÒÌ·ÙÔ˜ Î·È Ë ÔÓÔÌ·Û›· ÚÔ¤Ú¯ÂÙ·È ·fi ÙÔÓ Joseph Baddeley8 Ô˘ ·Ó·Î¿Ï˘„ ÙÔ ÚÒÙÔ ¤Ùڈ̷ ÛÙË Sri Lanka ÙÔ Hellenic Stomatological Review 57: 101-137, 2013 ceramics so as to avoid fracture and keep all the other qualities that make them unique. The development of these materials has been rapid in recent years and the aim was to increase the strength and improve the aesthetics. The metal core of fixed prosthetic restorations continues to this day to be the most reliable solution to support ceramics. However, the need for better aesthetic performance of ceramic restorations led to efforts to replace the opaque metal core, which makes difficult to adapt the color of the natural tooth. For these reasons, all-ceramic systems were developed in dentistry with many different approaches3. The most recent approach is the use of zirconia ceramic (ZrO2),- materials that have been used in industry, in electronics and in medicine as a material of orthopedics4. Zirconia today holds a special position in the field of dentistry as it has exploited both in the field of restorative dentistry - mainly as a core material of ceramic restorations, as well as a biomaterial of osseointegrated dental implants. It began to spread in the dental field since 2000 with wider acceptance after 20105. HISTORY Zirconium is known as a gemstone since ancient times. The zirconium metal with atomic number 40, has taken its name from the Arabic word zargon which means gold in color and comes from the Persian words zar (gold) and gun (color). The zirconium dioxide called zirconia ZrO2 was discovered by the German chemist Martin Heirich Klaproth in 1789, who described it as a separate item without even have it in pure metallic form6 (Encyclopedia Britannica). Zirconia was isolated by firing certain gems and used for many years with rare earth oxides as pigments for ceramics7. In nature ZrO2 (Zirconia) is present in the form of a rare rock and derives its name from Joseph Baddeley8 who discovered the first rock in Sri Lanka in 1892. The isolation of the pure oxide (ZrO2) was achieved in 1824 by the Swedish chemist Jons Jakob Barzelius by heating a mixture of potassium chloride and zirconium. In pure metallic form it was introduced in 19249. Another rock is also zirconitis (ZrSiO4) found in rounded or prismatic brown crystals. Transparent and blue varieties used as gems are produced by heating natural zirconitis. Therefore, because the source of zirconium by vaddeleyitis from South Africa was insufficient for industrial production, manufacturers utilized the sand rich of zirconitis8. In 1899 Walther Nerst (Nobel Chemistry 1920) observed that the mixed oxide 15% by weight Y2O3-ZrO2 behaved as an oxygen ion conductor (O2-) at elevated temperatures. The industrial application of the solid oxide electrolyte fuel cells (SOFC) began with the discovery and the use of stabilized cubic zirconia as a semiconductor. Before 1975, its use was restricted to a very limited refractory uses, today it is used in a very wide range of applications in industry, household appliances, medicine and dentistry10. Since 1980 zirconia ceramics became popular due to their very low thermal conductivity and specific crystal structure, since major difficulties in their processing have overcome11. 103 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review 1892. H ·ÔÌfiÓˆÛË ÙÔ˘ ηı·ÚÔ‡ ÔÍÂȉ›Ô˘ ZrO2 ‹ ˙ÈÚÎÔÓ›·˜ ÂÂÙ‡¯ıË ÙÔ 1824 ·fi ÙÔÓ ™Ô˘Ë‰fi XËÌÈÎfi Jons Jakob Barzelius Ì ÙËÓ ı¤ÚÌ·ÓÛË ÂÓfi˜ Ì›ÁÌ·ÙÔ˜ Î·Ï›Ô˘ Î·È ¯ÏˆÚȉ›Ô˘ ÙÔ˘ ˙ÈÚÎÔÓ›Ô˘. ™Â ηı·Ú‹ ÌÂÙ·ÏÏÈ΋ ÌÔÚÊ‹ ·ÚÔ˘ÛÈ¿ÛÙËΠÙÔ 19249. ŒÓ· ¿ÏÏÔ ¤Ùڈ̷ Â›Ó·È Î·È Ô ˙ÈÚÎÔÓ›Ù˘ (ZrSiO4) Ô˘ ‚Ú›ÛÎÂÙ·È Û ÚÈÛÌ·ÙÈÎÔ‡˜ ‹ Û ÛÙÚÔÁÁ˘ÏÂ̤ÓÔ˘˜ ÎÚ˘ÛÙ¿ÏÏÔ˘˜ ηʤ ¯ÚÒÌ·ÙÔ˜. ¢È·Ê·Ó›˜ Î·È ÌÏ ÔÈÎÈϛ˜ Ô˘ ¯ÚËÛÈÌÔÔÈÔ‡ÓÙ·È ˆ˜ ÔχÙÈÌÔÈ Ï›ıÔÈ ·Ú¿ÁÔÓÙ·È ·fi ÙË ı¤ÚÌ·ÓÛË ÙÔ˘ Ê˘ÛÈÎÔ‡ ˙ÈÚÎÔÓ›ÙË. EÂȉ‹ ÏÔÈfiÓ Ë ËÁ‹ ÙÔ˘ ˙ÈÚÎÔÓ›Ô˘ ·fi ÙÔÓ ‚·‰‰ÂÏÂ˚ÙË Ù˘ NÔÙ›Ô˘ AÊÚÈ΋˜ ‰ÂÓ Â·ÚÎÔ‡Û ÁÈ· ÙË ‚ÈÔÌ˯·ÓÈ΋ ·Ú·ÁˆÁ‹, ·ÍÈÔÔÈ‹ıËÎÂ Ë ¿ÌÌÔ˜ ÏÔ‡ÛÈ· Û ˙ÈÚÎÔÓ›ÙË8. TÔ 1899 Ô Walther Nerst (Nobel XËÌ›·˜ 1920) ·Ú·Ù‹ÚËÛ fiÙÈ ÙÔ ÌÈÎÙfi ÔÍ›‰ÈÔ 15% Î.‚. Y2O3-ZrO2 Û˘ÌÂÚÈÊÂÚfiÙ·Ó ˆ˜ ·ÁˆÁfi˜ ÈfiÓÙˆÓ O-2 Û ˘„ËϤ˜ ıÂÚÌÔÎڷۛ˜. H ‚ÈÔÌ˯·ÓÈ΋ ÂÊ·ÚÌÔÁ‹ ÛÙȘ ΢„¤Ï˜ η˘Û›ÌÔ˘ ÛÙÂÚÂÔ‡ ËÏÂÎÙÚÔχÙË (High temperature solid oxide fuel cells ‹ SOFC) ÍÂΛÓËÛ Ì ÙËÓ ·Ó·Î¿Ï˘„Ë ·˘Ù‹ Î·È ÙË ¯Ú‹ÛË Ù˘ ÛÙ·ıÂÚÔÔÈË̤Ó˘ ΢‚È΋˜ ˙ÈÚÎÔÓ›·˜ ˆ˜ ËÌÈ·ÁˆÁÔ‡. ¶ÚÈÓ ÙÔ 1975 Ë ¯Ú‹ÛË ÙÔ˘ ‹Ù·Ó ÂÚÈÔÚÈṲ̂ÓË Û ˘Ú›Ì·¯Â˜ ÂÊ·ÚÌÔÁ¤˜, ÂÓÒ Û‹ÌÂÚ· η٤¯ÂÈ ¤Ó· Â˘Ú‡Ù·ÙÔ Ê¿ÛÌ· ÂÊ·ÚÌÔÁÒÓ ÛÙË ‚ÈÔÌ˯·Ó›·, Û ÔÈÎȷΤ˜ Û˘Û΢¤˜, Î·È ÛÙËÓ È·ÙÚÈ΋ Î·È Ô‰ÔÓÙÈ·ÙÚÈ΋10. Afi ÙÔ 1980 fï˜ Ù· ÎÂÚ·ÌÈο ˙ÈÚÎÔÓ›·˜ ·Ó·Ù‡¯ıËÎ·Ó ÂÍ·ÈÚÂÙÈο ÏfiÁˆ ÙÔ˘ Ôχ ÌÈÎÚÔ‡ Û˘ÓÙÂÏÂÛÙ‹ ·ÁˆÁÈÌfiÙËÙ·˜ Î·È Ù˘ ȉȷ›ÙÂÚ˘ ÎÚ˘ÛÙ·ÏÏÈ΋˜ ÙÔ˘˜ ‰ÔÌ‹˜, ·ÊÔ‡ ÍÂÂÚ¿ÛÙËÎ·Ó Ù· ÚÔ‚Ï‹Ì·Ù· ηٿ ÙËÓ Î·ÙÂÚÁ·Û›· ÙÔ˘˜11. TÔ 1969 ÚÔÙ›ÓÂÙ·È Ë ¯Ú‹ÛË ‰ÈÔÍÂȉ›Ô˘ ÙÔ˘ ˙ÈÚÎÔÓ›Ô˘ ÛÙËÓ È·ÙÚÈ΋ Î·È ÈÔ Û˘ÁÎÂÎÚÈ̤ӷ ÛÙËÓ ÔÚıԷȉÈ΋ ˆ˜ ÂÓ·ÏÏ·ÎÙÈÎÔ‡ ˘ÏÈÎÔ‡ ÁÈ· ÔÏÈ΋ ·ÚıÚÔÏ·ÛÙÈ΋ ÎÂÊ·Ï‹˜ ÌËÚÈ·›Ô˘ ÛÙË ı¤ÛË ÙÔ˘ ÙÈÙ·Ó›Ô˘ Î·È Ù˘ ·ÏÔ˘Ì›Ó·˜12. ™ÙË Û˘Ó¤¯ÂÈ· ÚÔÙ¿ıËΠˆ˜ Ó¤Ô ˘ÏÈÎfi ÙÔ 1989 ÁÈ· ÙËÓ ÔÏÈ΋ ·ÚıÚÔÏ·ÛÙÈ΋ ÈÛ¯›Ô˘. ŒÎÙÔÙ ÂÚÈÛÛfiÙÂÚ˜ ·fi 600.000 ÎÂʷϤ˜ ¤¯Ô˘Ó ÙÔÔıÂÙËı› ·ÁÎfiÛÌÈ·13, 14. M¤¯ÚÈ Û‹ÌÂÚ· Ù· ÎÂÚ·ÌÈο ÎÚ¿Ì·Ù· ˙ÈÚÎÔÓ›·˜ ·ÔÙÂÏÔ‡Ó Ù· ÈÛ¯˘ÚfiÙÂÚ· ÌÔÓÔÊ·ÛÈο ÎÂÚ·ÌÈο ÔÍ›‰È· Ô˘ ¤¯Ô˘Ó ·Ú·¯ı›10. EÓÙÔ‡ÙÔȘ, ÙÔ 2002 ‹Ù·Ó Ë ¯ÚÔÓÈ¿ ηٿ ÙËÓ ÔÔ›· Ë ˙ÈÚÎÔÓ›· ˆ˜ ˘ÏÈÎfi Ù˘ ÔÚıԷȉÈ΋˜ ‰¤¯ÙËΠ‰ÚÈ̇ٷÙË ÎÚÈÙÈ΋ ηıÒ˜ ¤Ó·˜ ÛËÌ·ÓÙÈÎfi˜ ·ÚÈıÌfi˜ ÎÂÊ·ÏÒÓ ÌËÚÈ·›Ô˘ ÔÛÙÔ‡ (400) Ì ÙÔ ÂÌÔÚÈÎfi fiÓÔÌ· Prozyr Zirconia14 ·¤Ù˘¯·Ó Û in vivo ÏÂÈÙÔ˘ÚÁ›· ÙÔ 2001. TËÓ ›‰È· ¯ÚÔÓÈ¿ Ë ÂÙ·ÈÚ›· St. Gobain Desmarquest, Ô ÌÂÁ·Ï‡ÙÂÚÔ˜ ηٷÛ΢·ÛÙ‹˜ ÌËÚÈ·›ˆÓ ÎÂÊ·ÏÒÓ ˙ÈÚÎÔÓ›·˜, ·Ó·ÎÔ›ÓˆÛ ÙËÓ ·Ó¿ÎÏËÛË Û˘ÁÎÂÎÚÈÌ¤ÓˆÓ ·ÚÙ›‰ˆÓ ÏfiÁˆ ·ÔÎÏ›ÛÂˆÓ ÛÙË ıÂÚÌÈ΋ ηÙÂÚÁ·Û›· ηٿ ÙËÓ ·Ú·ÁˆÁ‹ ÙÔ˘˜. A˘Ù¤˜ ÔÈ ·ÚÙ›‰Â˜ Û˘Û¯ÂÙ›ÛÙËÎ·Ó Ì ÌÂÁ¿ÏÔ ·ÚÈıÌfi in vivo ηٷÁÌ¿ÙˆÓ15. AÓ Î·È Ë ¯Ú‹ÛË ˙ÈÚÎÔÓ›·˜ Û˘Ó¯›˙ÂÙ·È Û ÂÈÏÂÁ̤Ó˜ ·ÁÔÚ¤˜, fiˆ˜ Ë I·ˆÓ›·, Ë ·fiÛ˘ÚÛË Ù˘ Desmarquest ¤ÊÂÚ ·ÒÏÂÈ· Ù˘ ÂÌÈÛÙÔÛ‡Ó˘ Ù˘ ˙ÈÚÎÔÓ›·˜ ˆ˜ ·ÍÈfiÈÛÙÔ˘ ˘ÏÈÎÔ‡ ÛÙËÓ E˘ÚÒË Î·È ÙȘ Eӈ̤Ó˜ ¶ÔÏÈÙ›˜15. ¶·Ú¿ ÙÔ ÁÂÁÔÓfi˜ fiÙÈ ‰ÈÂÚ¢ӋıËÎ·Ó Ù· ·›ÙÈ· ÙˆÓ ·ÔÙ˘¯ÈÒÓ, ÛÙË Û˘Ó¤¯ÂÈ· ‰È·ÊÔÚÔÔÈ‹ıËÎ·Ó ÔÈ ÚԉȷÁڷʤ˜ ‰È·ÛÙ¿ÛÂˆÓ ÁÈ· ÙȘ ÎÂʷϤ˜, ·fi ÙÔ 2000 ¤ˆ˜ Û‹ÌÂÚ· ÂÁηٷÏ›ÂÙ·È Ë ¯Ú‹ÛË Ù˘ ˙ÈÚÎÔÓ›·˜ ÛÙËÓ ÔÚıԷȉÈ΋. °›ÓÔÓÙ·È ·ÚfiÏ· ·˘Ù¿ ÚÔÛ¿ıÂȘ ÁÈ· ηıȤڈÛË ¿ÏÏˆÓ Û‡ÓıÂÙˆÓ ˘ÏÈÎÒÓ ˙ÈÚÎÔÓ›·˜-·ÏÔ˘Ì›Ó·˜ ÛÙËÓ ÔÚıÔ104 In 1969 scientists proposed the use of zirconium dioxide in medicine and more specifically in orthopedics as an alternative material for replacing the femoral heads in place of the alumina and titanium12. Consequently, it was proposed as a new material in 1989 for total hip arthroplasty. Since then, more than 600,000 zirconia heads are installed worldwide13, 14. Hitherto zirconia ceramic alloys are the strongest single phase oxide ceramics ever produced10. However in 2002 zirconia materials were heavily criticized in orthopedics. The reason was that a substantial number of femoral heads (400) under the brand name Prozyr Zirconia14 failed in function in 2001. Despite the fact that the causes of failures were investigated since then and the dimensional specifications for the heads were differentiated, from 2000 to today clinicians abandoned the use of zirconia in orthopedics. Nevertheless many efforts were made to introduce other composites of zirconia - alumina in orthopedics, which retain the advantages of zirconia and do not present the serious drawback of aging and low temperature degradation16. Unlike its use in dentistry has increased with an annual sales increase of 12%14. Zirconium as an element of the periodic table belongs to the IVB transition metals group. Characteristic of this group is that ions in conventional oxidation state have completed some subshell d17.The transition elements are used in many alloys and often form colored compounds. Their atoms have an unsupplemented inner cortex (layer) which has electron vacancies. At ambient temperature, it has a closed hexagonal crystal structure and physical and chemical properties similar to the titanium18. MATERIAL PRODUCTION Zirconium is strong, lustrous and corrosion resistant with atomic number 40 and atomic weight 91,229. It is abundant in nature, it ranks 18th in the amount of crust and its concentration is 130 mg/kg in the cortex and 0.026mg/L at sea19. Pure zirconium is present in crystalline form as white and malleable metal, and amorphous as a dark blue powder. There is no free pure zirconium in nature and it exists only as oxide or in combination with silicas9. The zircon is the main commercial source of zirconium and is found primarily in Australia, South Wales, Brazil, India and South Africa20. The annual world production of zirconium is 900.000 tonnes19. Zirconium has many similarities with the element Hf (Hafnium), which is attached to various minerals and their separation becomes difficult21. As a metal has many uses and applications in photographic flashes, surgical instruments and as a hardener of alloys in nuclear reactors18. Zirconium dioxide presents a white crystalline form called zirconia. Minerals that contain it are zircon (ZrSiO4) (Fig.1) and baddeleyte (ZrO2) (Fig. 2). Zirconia is oxidation resistable and does not react with acids and bases at room temperature with the exception of hydrogen fluoride (HF). It reacts with carbon, nitrogen and hydrogen at temperatures above 2200ÆC14. Hellenic Stomatological Review 57: 101-137, 2013 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review ·È‰È΋, Ô˘ ‰È·ÙËÚÔ‡Ó Ù· ÏÂÔÓÂÎÙ‹Ì·Ù· Ù˘ ˙ÈÚÎÔÓ›·˜ Î·È ‰ÂÓ ¤¯Ô˘Ó ÙÔ ÛÔ‚·Úfi ÌÂÈÔÓ¤ÎÙËÌ· Ù˘ Á‹Ú·ÓÛ˘16. AÓÙ›ıÂÙ· Ë ¯Ú‹ÛË Ù˘ ÛÙËÓ Ô‰ÔÓÙÈ·ÙÚÈ΋ ·˘Í‹ıËΠ̠ÂÙ‹ÛÈ· ·‡ÍËÛË ˆÏ‹ÛÂˆÓ 12%14. ¶POE§EY™H - ¶APA°ø°H ZIPKONIOY - ZIPKONIA™ TÔ ˙ÈÚÎfiÓÈÔ ˆ˜ ÛÙÔÈ¯Â›Ô ÙÔ˘ ÂÚÈÔ‰ÈÎÔ‡ ›Ó·Î· ·Ó‹ÎÂÈ ÛÙ· ̤ٷÏÏ· ÌÂٿوÛ˘ ÛÙËÓ IVB ÔÌ¿‰·. X·Ú·ÎÙËÚÈÛÙÈÎfi ·˘Ù‹˜ Ù˘ ÔÌ¿‰·˜ Â›Ó·È fiÙÈ Ù· ÈfiÓÙ· ÙÔ˘˜ ÛÂ Û˘ÓËıÈṲ̂ÓË Î·Ù¿ÛÙ·ÛË ÔÍ›‰ˆÛ˘ ¤¯Ô˘Ó ÌÂÚÈο Û˘ÌÏËڈ̤ÓÔ ÙÔÓ ˘ÔÊÏÔÈfi d17. T· ÛÙÔȯ›· ÌÂٿوÛ˘ ¯ÚËÛÈÌÔÔÈÔ‡ÓÙ·È Û ÔÏÏ¿ ÎÚ¿Ì·Ù· Î·È Û˘¯Ó¿ Û¯ËÌ·Ù›˙Ô˘Ó ¤Á¯ÚˆÌ˜ ÂÓÒÛÂȘ. T· ¿ÙÔÌ¿ ÙÔ˘˜ ‰È·ı¤ÙÔ˘Ó Î¿ÔÈÔ ÌË Û˘ÌÏËڈ̤ÓÔ ÂÛˆÙÂÚÈÎfi ÊÏÔÈfi (ÛÙÈ‚¿‰·) Ô˘ ¤¯ÂÈ ÎÂÓ¤˜ ı¤ÛÂȘ ËÏÂÎÙÚÔÓ›ˆÓ. ™Â ıÂÚÌÔÎÚ·Û›· ÂÚÈ‚¿ÏÏÔÓÙÔ˜ ¤¯ÂÈ ÎÏÂÈÛÙ‹ ÂÍ·ÁˆÓÈ΋ ÎÚ˘ÛÙ·ÏÏÈ΋ ‰ÔÌ‹ Î·È Ê˘ÛÈΤ˜ Î·È ¯ËÌÈΤ˜ ȉÈfiÙËÙ˜ ·ÚfiÌÔȘ Ì ÙÔ ÙÈÙ¿ÓÈÔ18. TÔ ˙ÈÚÎfiÓÈÔ Â›Ó·È ÈÛ¯˘Úfi, ÛÙÈÏÓfi Î·È ÂÍ·ÈÚÂÙÈο ·ÓıÂÎÙÈÎfi ÛÙË ‰È¿‚ÚˆÛË Ì ·ÙÔÌÈÎfi ·ÚÈıÌfi 40 Î·È ·ÙÔÌÈÎfi ‚¿ÚÔ˜ 91,229. Y¿Ú¯ÂÈ ¿ÊıÔÓÔ ÛÙË Ê‡ÛË, η٤¯ÂÈ ÙËÓ 18Ë ı¤ÛË Û ÔÛfiÙËÙ· ÛÙÔ ÊÏÔÈfi Ù˘ Á˘ Î·È ÔÈ Û˘ÁÎÂÓÙÚÒÛÂȘ ÙÔ˘ Â›Ó·È 130 mg/kg ÛÙÔ ÊÏÔÈfi Î·È 0.026Ìg/l ÛÙË ı¿Ï·ÛÛ·19. TÔ Î·ı·Úfi ˙ÈÚÎfiÓÈÔ ˘¿Ú¯ÂÈ Û ÎÚ˘ÛÙ·ÏÏÈ΋ ÌÔÚÊ‹ ˆ˜ Ï¢Îfi Î·È ÂÏ·Ùfi ̤ٷÏÏÔ Î·È Û ¿ÌÔÚÊË ˆ˜ ÛÎÔ‡Ú· ÌÏ ÛÎfiÓË. ¢ÂÓ ˘¿Ú¯ÂÈ ÂχıÂÚÔ Î·ı·Úfi ˙ÈÚÎfiÓÈÔ ÛÙË Ê‡ÛË ·Ú¿ ÌfiÓÔ ˆ˜ ÔÍ›‰ÈÔ ‹ ÛÂ Û˘Ó‰˘·ÛÌfi Ì ˘ÚÈÙÈο ÔÍ›‰È·9. O ˙ÈÚÎÔÓ›Ù˘ Â›Ó·È Ë Î‡ÚÈ· ÂÌÔÚÈ΋ ËÁ‹ ÙÔ˘ ˙ÈÚÎÔÓ›Ô˘ Î·È ‚Ú›ÛÎÂÙ·È ÚˆÙ›ÛÙˆ˜ Û A˘ÛÙÚ·Ï›·, NfiÙÈ· O˘·Ï›·, BÚ·˙ÈÏ›·, IÓ‰›· Î·È NfiÙÈ· AÊÚÈ΋20. H ÂÙ‹ÛÈ· ·ÁÎfiÛÌÈ· ·Ú·ÁˆÁ‹ ˙ÈÚÎÔÓ›Ô˘ Â›Ó·È 900.000 ÙfiÓÔÈ19. TÔ ˙ÈÚÎfiÓÈÔ ¤¯ÂÈ ÔÏϤ˜ ÔÌÔÈfiÙËÙ˜ Ì ÙÔ ÛÙÔÈ¯Â›Ô Hf (ÕÊÓÈÔ), Ì ÙÔ ÔÔ›Ô ‚Ú›ÛÎÂÙ·È Ì·˙› Û ‰È¿ÊÔÚ· ÔÚ˘ÎÙ¿ Î·È Ô ‰È·¯ˆÚÈÛÌfi˜ ÙÔ˘˜ ηı›ÛÙ·Ù·È ‰˘Û¯ÂÚ‹˜21. ø˜ ̤ٷÏÏÔ ¤¯ÂÈ ·ÚÎÂÙ¤˜ ¯Ú‹ÛÂȘ Î·È ÂÊ·ÚÌÔÁ¤˜ Û ʈÙÔÁÚ·ÊÈο ÊÏ·˜, ¯ÂÈÚÔ˘ÚÁÈο ÂÚÁ·Ï›·, ˆ˜ ÛÎÏËÚ˘ÓÙ‹˜ ÎÚ·Ì¿ÙˆÓ Î·È Û ˘ÚËÓÈÎÔ‡˜ ·ÓÙȉڷÛÙ‹Ú˜18. TÔ ‰ÈÔÍ›‰ÈÔ ÙÔ˘ ˙ÈÚÎÔÓ›Ô˘ ¤¯ÂÈ Ï¢΋ ÎÚ˘ÛÙ·ÏÏÈ΋ ÌÔÚÊ‹ Î·È ÔÓÔÌ¿˙ÂÙ·È ˙ÈÚÎÔÓ›·. Ÿˆ˜ ·ÓÙ›ÛÙÔȯ· Î·È ÛÙÔ Î·ı·Úfi ˙ÈÚÎfiÓÈÔ ‰ÂÓ ˘Ê›ÛÙ·Ù·È Î·ı·Ú‹ ˙ÈÚÎÔÓ›· ÛÙË Ê‡ÛË. T· ÔÚ˘ÎÙ¿ ÛÙ· ÔÔ›· ÂÌÂÚȤ¯ÂÙ·È fiˆ˜ ÚԷӷʤÚıËÎ·Ó Â›Ó·È Ô ˙ÈÚÎÔÓ›Ù˘ (ZrSiO4) (EÈÎ. 1) Î·È Ô ‚·‰‰ÂÏ½Ù˘ (ZrO2) (EÈÎ. 2). H ˙ÈÚÎÔÓ›· Â›Ó·È ÛÙ·ıÂÚ‹ ÛÙËÓ ÔÍ›‰ˆÛË Î·È ‰ÂÓ ·ÓÙȉڿ Ì Ôͤ· Î·È ‚¿ÛÂȘ ÛÙË ıÂÚÌÔÎÚ·Û›· ‰ˆÌ·Ù›Ô˘ Ì ÂÍ·›ÚÂÛË ÙÔ ˘‰ÚÔÊıfiÚÈÔ (HF). AÓÙȉڿ Ì ÙÔÓ ¿Óıڷη, ÙÔ ¿˙ˆÙÔ Î·È ÙÔ ˘‰ÚÔÁfiÓÔ Û ıÂÚÌÔÎڷۛ˜ ¿Óˆ ÙˆÓ 2200ÆC14. EÈÎ. 1: ZÈÚÎÔÓ›Ù˘ (ηʤ ¯ÚÒÌ·ÙÔ˜, ÚÈÛÌ·ÙÈÎfi˜) Fig. 1: Zirkonitis (brown color, prismatic) www.en.wikipedia.org/wiki.zircon EÈÎ. 2: B·‰‰ÂÏÂ˚Ù˘ Fig. 2: Baddeleyte www.en.wikipedia.org/wiki.baddeleyte EÈÎ. 3: AÏÏÔÙÚÔÈΤ˜ ÌÔÚʤ˜ ˙ÈÚÎÔÓ›·˜ ·) ΢‚È΋ (c-phase) ‚) ÙÂÙÚ·ÁˆÓÈ΋ (t-phase) Á) ÌÔÓÔÎÏÈÓ‹˜ (m-phase) ·fi ¶ÂÙÚfiÔ˘ÏÔ˜ 200111 Fig. 3: Allotropic forms of zirconia a) cubic b) tetragonal c) monoclinic from Petropoulos 200111 Microstructure MIKPO¢OMH - ATOMIKH ¢IEY£ETH™H - KPY™TA§§IKE™ MOPºE™ H ˙ÈÚÎÔÓ›· ·ÚÔ˘ÛÈ¿˙ÂÈ ÙÔ Ê·ÈÓfiÌÂÓÔ ÙÔ˘ ÔÏ˘ÌÔÚÊÈÛÌÔ‡ ‰ËÏ·‰‹ ÎÚ˘ÛÙ·ÏÏÒÓÂÙ·È Ì ÙÚÂȘ ‰È·ÊÔÚÂÙÈÎÔ‡˜ ÙÚfiÔ˘˜. OÈ ÙÚÂȘ ÎÚ˘ÛÙ·ÏÏÈΤ˜ ÌÔÚʤ˜ Ù˘ ˙ÈÚÎÔÓ›·˜ ›ӷÈ: ·) Ë Î˘‚È΋, ¤Ó· ¢ı‡ ϤÁÌ· Ì ÙÂÙÚ¿ÁˆÓ˜ Ï¢ڤ˜ ‚) Ë ÙÂÙÚ·ÁˆÓÈ΋, ¤Ó· ¢ı‡ ϤÁÌ· Ì ÔÚıÔÁÒÓÈÔ Û¯‹Ì· Î·È Ë Á) Ë ÌÔÓÔÎÏÈÓ‹˜, ¤Ó· ·Ú·ÌÔÚʈ̤ÓÔ Ï¤ÁÌ· Û ۯ‹Ì· ·Ú·ÏÏËÏÂȤ‰Ô˘ (EÈÎ. 3). Hellenic Stomatological Review 57: 101-137, 2013 Zirconia exhibits the phenomenon of polymorphism and is crystallized in three different ways. The three crystallographic forms of zirconia are: a) the cubic, a rectangular grid with straight sides b) the tetragonal, a rectangular grid with a straight shape, and c) the monoclinic, a deformed grid parallelepiped-shaped (Fig. 3). Each crystallographic form has different properties. During heating, changes of the zirconia crystal structure take place. The monoclinic is stable at room temperature 105 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review K¿ı ÎÚ˘ÛÙ·ÏÏÈ΋ ÌÔÚÊ‹ ¤¯ÂÈ ‰È·ÊÔÚÂÙÈΤ˜ ȉÈfiÙËÙ˜. K·Ù¿ ÙË ı¤ÚÌ·ÓÛË Ù˘ ˙ÈÚÎÔÓ›·˜ ·Ú·ÙËÚÔ‡ÓÙ·È ·ÏÏ·Á¤˜ ÙˆÓ ÎÚ˘ÛÙ·ÏÏÈÎÒÓ ‰ÔÌÒÓ. H ÌÔÓÔÎÏÈÓ‹˜ Â›Ó·È ÛÙ·ıÂÚ‹ Û ıÂÚÌÔÎÚ·Û›· ‰ˆÌ·Ù›Ô˘ Î·È ‰È·ÙËÚÂ›Ù·È Ì¤¯ÚÈ ÙÔ˘˜ 1170ÆC, ¤¯ÂÈ ÌÂȈ̤Ó˜ Ì˯·ÓÈΤ˜ ȉÈfiÙËÙ˜ Û ۯ¤ÛË Ì ÙËÓ ÙÂÙÚ·ÁˆÓÈ΋ Î·È ÂËÚ¿˙ÂÈ ÙË Û˘ÓÔ¯‹ ÙˆÓ ÎÂÚ·ÌÈÎÒÓ ÎÚ˘ÛÙ¿ÏÏˆÓ Î·È ÙËÓ ˘ÎÓfiÙËÙ·. H ÙÂÙÚ·ÁˆÓÈ΋ Â›Ó·È ÛÙ·ıÂÚ‹ ÌÂٷ͇ 1170ÆC Î·È 2370ÆC Î·È ÚÔÛ‰›‰ÂÈ ÛÙÔ ˘ÏÈÎfi ‚ÂÏÙȈ̤Ó˜ Ì˯·ÓÈΤ˜ ȉÈfiÙËÙ˜. H ΢‚È΋ Â›Ó·È ÛÙ·ıÂÚ‹ Û ıÂÚÌÔÎڷۛ˜ ¿Óˆ ÙˆÓ 2370ÆC ̤¯ÚÈ ÙÔ ÛËÌÂ›Ô Ù‹Í˘22 Î·È ¤¯ÂÈ Ì¤ÙÚȘ Ì˯·ÓÈΤ˜ ȉÈfiÙËÙ˜. K·Ù¿ ÙË ‰È¿ÚÎÂÈ· Ù˘ „‡Í˘ ÙÔ˘ ˘ÏÈÎÔ‡ ÙÔ Ê·ÈÓfiÌÂÓÔ ·ÓÙÈÛÙÚ¤ÊÂÙ·È Î·È Û ıÂÚÌÔÎÚ·Û›· 950ÆC ÍÂÎÈÓ¿ÂÈ Ë ÌÂÙ·ÙÚÔ‹ Ù˘ ÙÂÙÚ·ÁˆÓÈ΋˜ Û ÌÔÓÔÎÏÈÓ‹7, 8. H ÌÂÙ·‚ÔÏ‹ Ê¿ÛÂˆÓ ·ÎÔÏÔ˘ıÂ›Ù·È Î·È ·fi ÌÂÙ·‚ÔÏ‹ fiÁÎÔ˘ ÙÔ˘ ˘ÏÈÎÔ‡. K·Ù¿ ÙËÓ ÌÂÙ·ÙÚÔ‹ Ù˘ ÙÂÙÚ·ÁˆÓÈ΋˜ Û ÌÔÓÔÎÏÈÓ‹ (t->m) ·Ú·ÙËÚÂ›Ù·È ·‡ÍËÛË ÙÔ˘ fiÁÎÔ˘ ηٿ 4,5% ÂÚ›Ô˘ ÂÓÒ Ù˘ ΢‚È΋˜ Û ÙÂÙÚ·ÁˆÓÈ΋ (c->t) 2,31%23. ŒÓ·˜ ‰È·ÊÔÚÂÙÈÎfi˜ ÌÂÙ·Û¯ËÌ·ÙÈÛÌfi˜ (c—>t) ÌÔÚ› Ó· ÚÔηϤÛÂÈ ÙË ‰ËÌÈÔ˘ÚÁ›· ÌÈ·˜ ‰È·ÊÔÚÂÙÈ΋˜ t Ê¿Û˘. A˘Ù‹ Ë Ê¿ÛË t, ÁÓˆÛÙ‹ ˆ˜ t’, ıˆÚÂ›Ù·È fiÌÔÈ· Ù˘ t, ·ÏÏ¿ Ì ÂÚÈÛÛfiÙÂÚË ÂÚÈÂÎÙÈÎfiÙËÙ· Û ‡ÙÙÚÈÔ, ÌÈÎÚfiÙÂÚÔ Ì¤ÁÂıÔ˜ ÎÚ˘ÛÙ¿ÏÏˆÓ Î·È È‰È·›ÙÂÚË ·ÓÙ›ÛÙ·ÛË ÛÙË ÌÂÙ·ÙÚÔ‹ Ù˘ Û ʿÛË m24. O ÌÂÙ·Û¯ËÌ·ÙÈÛÌfi˜ ·˘ÙÔ‡ ÙÔ˘ Ù‡Ô˘ Ê·›ÓÂÙ·È Ó· ÂÚÈÔÚ›˙ÂÈ ÙȘ ÁÓˆÛÙ¤˜ ·ÚÓËÙÈΤ˜ Û˘Ó¤ÂȘ Ù˘ ·Ó¿Ù˘Í˘ Ù˘ Ê¿Û˘ m, ηٿ ÙË Á‹Ú·ÓÛË Ù˘ ˙ÈÚÎÔÓ›·˜ Û ıÂÚÌÔÎÚ·Û›· ÂÚÈ‚¿ÏÏÔÓÙÔ˜. A˘Ù¤˜ ÔÈ ÌÂÙ·ÙÚÔ¤˜ ÙÔ˘ ϤÁÌ·ÙÔ˜ Â›Ó·È Ì·ÚÙÂÓÛÈÙÈÎÔ‡ Ù‡Ô˘ Î·È ¯·Ú·ÎÙËÚ›˙ÔÓÙ·È ·fi ÙÚ›· ÛËÌ›·. ¶ÚÒÙÔ, ÙËÓ ¤ÏÏÂÈ„Ë ‰È¿¯˘Û˘ (ÂÚÈÏ·Ì‚¿ÓÔ˘Ó ÌfiÓÔ Û˘ÓÙÔÓÈṲ̂Ó˜ ·ÏÏ·Á¤˜ ÛÙȘ ı¤ÛÂȘ ÙÔ˘ ϤÁÌ·ÙÔ˜ ¯ˆÚ›˜ ÌÂٷΛÓËÛË ·ÙfïÓ). ¢Â‡ÙÂÚÔ, fiÙÈ ÔÈ ÌÂÙ·ÙÚÔ¤˜ ·˘Ù¤˜ Û˘Ì‚·›ÓÔ˘Ó Î·Ù¿ ÙË ‰È¿ÚÎÂÈ· ÌÂÙ·‚ÔÏ‹˜ Û ¤Ó· ıÂÚÌÔÎÚ·ÛÈ·Îfi ‰È¿ÛÙËÌ· ·Ú¿ Û ̛· Û˘ÁÎÂÎÚÈ̤ÓË ıÂÚÌÔÎÚ·Û›· Î·È ÙÚ›ÙÔ Ë ·Ú·ÌfiÚʈÛË ÙÔ˘ Û¯‹Ì·ÙÔ˜25. TÔ Ê·ÈÓfiÌÂÓÔ ·˘Ùfi ÚÒÙË ÊÔÚ¿ ·Ú·ÙËÚ‹ıËΠÛÙ· ÎÚ¿Ì·Ù· Ûȉ‹ÚÔ˘-¯·ÏÎÔ‡ Ì ÙË ÌÂÙ·ÙÚÔ‹ ÙÔ˘ ÔÛÙÂÓ›ÙË Û ̷ÚÙÂÓÛ›ÙË Î·È ÙËÓ ·ÓÙ›ÛÙÔÈ¯Ë ÂÍ·ÈÚÂÙÈ΋ ‚ÂÏÙ›ˆÛË ÙˆÓ Ì˯·ÓÈÎÒÓ È‰ÈÔÙ‹ÙˆÓ ÙÔ˘ ÎÚ¿Ì·ÙÔ˜26. O•EI¢IA ™TA£EPO¶OIH™H™ ºA™EøN H ˙ÈÚÎÔÓ›· ÁÈ· Ó· ÌÔÚ¤ÛÂÈ Ó· Ì·˜ ·Ú¤¯ÂÈ ÙȘ ··ÈÙÔ‡ÌÂÓ˜ ȉÈfiÙËÙ˜ ÚÔ¸Ôı¤ÙÂÈ ÛÙ·ıÂÚÔÔ›ËÛË Ù˘ t-Ê¿Û˘ Û ıÂÚÌÔÎÚ·Û›· ÂÚÈ‚¿ÏÏÔÓÙÔ˜. H ÌÔÓÔÎÏÈÓ‹˜ ÌÔÚÊ‹ Ù˘ ˙ÈÚÎÔÓ›·˜ ·ÔÙÂÏÔ‡Û ÂÌfi‰ÈÔ ÛÙË ‰ËÌÈÔ˘ÚÁ›· ÂÓfi˜ ·ÓıÂÎÙÈÎÔ‡ ÎÂÚ·ÌÈÎÔ‡ Ô˘ ı· ÌÔÚÔ‡Û ӷ ¯ÚËÛÈÌÔÔÈËı› Û ‰È¿ÊÔÚ˜ ÂÊ·ÚÌÔÁ¤˜. OÈ ÂÓ·ÏÏ·Á¤˜ fiÁÎÔ˘ ÏfiÁˆ ÌÂÙ·ÙÚÔ‹˜ Ê¿ÛÂˆÓ ÂÈÛ¿ÁÔ˘Ó Ù¿ÛÂȘ Î·È ‰ËÌÈÔ˘ÚÁÔ‡Ó ÚˆÁ̤˜ ÛÙË Ì¿˙· ÙÔ˘ ˘ÏÈÎÔ‡ ÌÂÈÒÓÔÓÙ·˜ ÙȘ Ì˯·ÓÈΤ˜ ·ÓÙÔ¯¤˜ ÙÔ˘ ˘ÏÈÎÔ‡26. OÈ ÚÔÛ¿ıÂȘ ÙˆÓ ¯ËÌÈÎÒÓ Ì˯·ÓÈÎÒÓ ÍÂΛÓËÛ·Ó Á‡Úˆ ÛÙÔ 1972 fiÙ·Ó ·Ó·Î¿Ï˘„·Ó fiÙÈ Î·Ù¿ ÙË ‰ËÌÈÔ˘ÚÁ›· ÎÚ·Ì¿ÙˆÓ ˙ÈÚÎÔÓ›·˜ Ì ÚÔÛı‹ÎË ÔÍÂȉ›ˆÓ ¯·ÌËÏfiÙÂÚÔ˘ Ûı¤ÓÔ˘˜ (CaO, MgO, La2O3, Y2O3) ¢ÓÔÔ‡ÓÙ·Ó Ë Î˘‚È΋ Î·È Ë ÙÂÙÚ·ÁˆÓÈ΋ ÌÔÚÊ‹23. H ÛÙ·ıÂÚÔÔ›ËÛË Ù˘ ˙ÈÚÎÔÓ›·˜ Á›ÓÂÙ·È Ì ÙËÓ ·ÓÙÈηٿÛÙ·ÛË ÙÔ˘ Zr4+ ·fi ÙÔ Y3+ ÛÙÔ Ï¤ÁÌ·. TÔ ·Ú·¿Óˆ Ô‰ËÁ› ÙÔ Û¯ËÌ·ÙÈÛÌfi ÎÂÓÒÓ ÂÓ‰ÔÏÂÁÌ·ÙÈÎÒÓ ı¤ÛÂˆÓ Èfi106 and kept up to 1170ÆC, has reduced mechanical properties compared to the tetragonal and influences the consistency of the ceramic crystal and density. The tetragonal is constant between 1170ÆC and 2370ÆC and gives the material improved mechanical properties. The cubic is stable at temperatures in excess of 2370ÆC until the melting point22 and has moderate mechanical properties. During the cooling of the material the phenomenon is reversed, and at the temperature 950ÆC the conversion of the tetragonal to monoclinic form starts7, 8. This phase transformation is followed by a change in volume of the material. During the conversion of the tetragonal to monoclinic (t-> m) phase a volume increase of about 4.5% is observed, while the respective volume change for the transformation of cubic to tetragonal (c-> t) is 2,31%29. A different transformation (c -> t) can cause the creation of a different t phase. This is known as t’, it is considered like t, but contains more yttrium, attains smaller crystal size and presents higher resistance to t->m phase transformation24. This type of transformation appears to limit the known negative consequences of the m phase development, during aging of zirconia at room temperature. First, there is lack of diffusion (they include coordinated changes in the positions of the crystal matrix without atomic moving). Second, they take place in a temperature range instead of a specific temperature and third, there is distortion of the shape25.This phenomenon was first observed in the iron - copper alloys by converting ostenite to martensite and the corresponding outstanding improvement of the mechanical properties of the alloy26 . PHASE STABILIZATION OXIDES Zirconia in order to provide the required properties needs the stabilization of the t- phase at ambient temperature. The presence of monoclinic zirconia is an obstacle to the creation of a durable ceramic that could be used in various applications. The volume variation due to the phase transformation creates cracks in the mass of the material by reducing its mechanical strength26. Efforts of chemical engineers began around 1972 when they discovered that alloying with lower valence oxides (CaO, MgO, La2O3, Y2O3) favored the cubic and quadratic form23. The stabilization of t zirconia is achieved by the replacement of Zr4 + ions from Y3 + in the matrix. The above leads to the formation of oxygen voids inside the crystal matrix which are known as oxygen vacancies and their mobility in the matrix causes ionic conductivity. In essence, with the addition of Y3 + lattice defects are generated. The phases formed are now similar to those of pure zirconia with the difference that the impurity - ion stabilizers replace Zr +4 ions create intracellular positions of oxygen ions in order to maintain neutrality when it comes to trivalent stabilizer (Fig. 4). A total of three mechanisms are taking place for the stabilization of the t- phase and the most common impurities or stabilizers are cerium dioxide (CeO2) and yttrium trioxide (Y2O3): a) trivalent ions which create Hellenic Stomatological Review 57: 101-137, 2013 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review ÓÙˆÓ Ô͢ÁfiÓÔ˘ Ô˘ ·ÔÙÂÏÔ‡Ó ÙÔ˘˜ ÊÔÚ›˜ Ù˘ ·ÁˆÁÈÌfiÙËÙ·˜, Ë ÎÈÓËÙÈÎfiÙËÙ¿ ÙÔ˘˜ ÛÙÔ Ï¤ÁÌ· ·ÔÙÂÏ› ÙËÓ ÈÔÓÙÈ΋ ·ÁˆÁÈÌfiÙËÙ·. ™ÙËÓ Ô˘Û›· Ì ÙËÓ ÚÔÛı‹ÎË ÙÔ˘ Y3+ ‰ËÌÈÔ˘ÚÁÔ‡ÓÙ·È ·Ù¤ÏÂȘ ÛÙÔ Ï¤ÁÌ·. OÈ Ê¿ÛÂȘ Ô˘ ‰ËÌÈÔ˘ÚÁÔ‡ÓÙ·È Ï¤ÔÓ Â›Ó·È ·Ó¿ÏÔÁ˜ Ì ·˘Ù¤˜ Ù˘ ηı·Ú‹˜ ˙ÈÚÎÔÓ›·˜ Ì ÙË ‰È·ÊÔÚ¿ fiÙÈ Ù· ÈfiÓÙ· ÚfiÛÌÈ͢-ÛÙ·ıÂÚÔÔÈËÙÒÓ ·ÓÙÈηıÈÛÙÔ‡Ó Ù· Zr+4 ÈfiÓÙ· Î·È ‰ËÌÈÔ˘ÚÁÔ‡Ó ÙÔ Û¯ËÌ·ÙÈÛÌfi ÎÂÓÒÓ ÂÓ‰ÔÏÂÁÌ·ÙÈÎÒÓ ı¤ÛÂˆÓ ÈfiÓÙˆÓ Ô͢ÁfiÓÔ˘ ÚÔÎÂÈ̤ÓÔ˘ Ó· ‰È·ÙËÚËı› Ë Ô˘‰ÂÙÂÚfiÙËÙ·, fiÙ·Ó ÚfiÎÂÈÙ·È ÁÈ· ÙÚÈÛıÂÓ‹ ÛÙ·ıÂÚÔÔÈËÙ‹ (EÈÎ. 4). ™˘ÓÔÏÈο ÙÚÂȘ Ì˯·ÓÈÛÌÔ› ÏÂÈÙÔ˘ÚÁÔ‡Ó ÁÈ· ÙË ÛÙ·ıÂÚÔÔ›ËÛË Ù˘ t-Ê¿Û˘ Î·È ÔÈ Ï¤ÔÓ Û˘Ó‹ıÂȘ ÚÔÛÌ›ÍÂȘÛÙ·ıÂÚÔÔÈËÙ¤˜ Â›Ó·È ÙÔ ‰ÈÔÍ›‰ÈÔ ÙÔ˘ ‰ËÌËÙÚ›Ô˘ (CeO2) Î·È ÙÔ ÙÚÈÔÍ›‰ÈÔ ÙÔ˘ ˘ÙÙÚ›Ô˘ (Y2O3): ·) ÙÚÈÛıÂÓ‹ ÈfiÓÙ· Ù· ÔÔ›· ‰ËÌÈÔ˘ÚÁÔ‡Ó Ô¤˜ Ô͢ÁfiÓÔ˘ Fe+3, Ga+3, Y+3 ‚) ÙÂÙÚ·ÛıÂÓ‹ ÈfiÓÙ· Ì ÌÈÎÚfiÙÂÚÔ ‹ ÌÂÁ·Ï‡ÙÂÚÔ fiÁÎÔ (Ti+4, Ce+4) Á) ÚÔÛÌ›ÍÂȘ ÊÔÚÙ›Ô˘ ·ÓÙÈÛÙ¿ıÌÈÛ˘23. ™ËÌ·ÓÙÈ΋ ¿ÓÙˆ˜ ¤Ú¢ӷ ¤¯ÂÈ Á›ÓÂÈ ÛÙ· ÎÂÚ·ÌÈο Ô˘ ÛÙËÚ›˙ÔÓÙ·È ÛÙË ˙ÈÚÎÔÓ›·. Œ¯Ô˘Ó ‰ÔÎÈÌ·ÛÙ› ‰È·ÊÔÚÂÙÈΤ˜ ̤ıÔ‰ÔÈ Û‡ÓıÂÛ˘ Î·È ÁÈ· ÙË ÛÙ·ıÂÚÔÔ›ËÛ‹ Ù˘ ¤¯Ô˘Ó ‰ÔÎÈÌ·ÛÙ› Ù· ÔÍ›‰È· Ì·ÁÓËÛ›Ô˘, ·Û‚ÂÛÙ›Ô˘, ‰ËÌËÙÚ›Ô˘ Î·È ˘ÙÙÚ›Ô˘ (MgO, CaO, CeO2, Y2O3) ηıÒ˜ Î·È ÔÍ›‰È· Û¿ÓÈˆÓ Á·ÈÒÓ27. T· Ó¤· ·˘Ù¿ ÎÂÚ·ÌÈο ˙ÈÚÎÔÓ›·˜ Î·È ÈÔ Û˘ÁÎÂÎÚÈ̤ӷ Ë ÌÂÚÈÎÒ˜ ÛÙ·ıÂÚÔÔÈË̤ÓË ˙ÈÚÎÔÓ›· (PSZ) ¯·Ú·ÎÙËÚ›ÛÙËÎ·Ó ·fi ÙÔ˘˜ Garvie Î·È Û˘Ó28 ˆ˜ «ÎÂÚ·ÌÈÎfi˜ ¯¿Ï˘‚·˜» ÁÈ·Ù› ÂÌÊ·Ó›˙Ô˘Ó ·ÚÎÂÙ¤˜ ÔÌÔÈfiÙËÙ˜ Ì ÙÔ ¯¿Ï˘‚· ηıÒ˜ ¤¯Ô˘Ó ÙÚÂȘ ·ÏÏÔÙÚÔÈΤ˜ ÌÔÚʤ˜, Ì·ÚÙÂÓÛÈÙÈÎÔ‡ Ù‡Ô˘ ÌÂÙ·ÙÚÔ‹ Ê¿Û˘, Î·È ÌÂÙ·‚ÏËÙ¤˜ Ê¿ÛÂȘ. MOPºE™ ENI™XYMENH™ ZIPKONIA™ A¶O METATPO¶H ºA™H™ O fiÚÔ˜ ÂÓÈÛ¯˘Ì¤Ó· ÎÂÚ·ÌÈο ÂÌÂÚȤ¯ÂÈ ÌÈ· ¢Ú›· Ù¿ÍË ˘ÏÈÎÒÓ Î·È ÌÈÎÚÔ‰ÔÌÒÓ29. H ÂÓÈÛ¯˘Ì¤ÓË ˙ÈÚÎÔÓ›· ¯ˆÚ›˙ÂÙ·È Û ÙÚÂȘ ‚·ÛÈΤ˜ ηÙËÁÔڛ˜. ™ÙȘ ‰˘Ô ÚÒÙ˜ ·ÔÙÂÏÂ›Ù·È ·fi ˘ÏÈο ÙÔ˘Ï¿¯ÈÛÙÔÓ ‰˘Ô Ê¿ÛÂˆÓ Ì ÙËÓ ÙÂÙÚ·ÁˆÓÈ΋ ˙ÈÚÎÔÓ›· Ó· ·ÔÙÂÏ› ÙË ÌÈÎÚfiÙÂÚË Ê¿ÛË ÂÓÒ Ë ÙÚ›ÙË Î·ÙËÁÔÚ›· ÂÚÈÏ·Ì‚¿ÓÂÈ Î·Ù¿ ·ÚÈÔ ÏfiÁÔ ÌÔÓÔÊ·ÛÈ΋ t-˙ÈÚÎÔÓ›·23. ™˘ÓÂÒ˜ ‰È·ÎÚ›ÓÔ˘ÌÂ: 1. Ù· ÎÂÚ·ÌÈο ÂÓÈÛ¯˘Ì¤Ó· Ì ˙ÈÚÎÔÓ›·, 2. T· ÎÂÚ·ÌÈο Ì ÌÂÚÈÎÒ˜ ÛÙ·ıÂÚÔÔÈË̤ÓË ÙÂÙÚ·ÁˆÓÈ΋ ˙ÈÚÎÔÓ›· Î·È 3. T· ÎÂÚ·ÌÈο Ì ϋڈ˜ ÛÙ·ıÂÚÔÔÈË̤ÓË ÙÂÙÚ·ÁˆÓÈ΋ ˙ÈÚÎÔÓ›·. 1. KEPAMIKA ENI™XYMENA ME ZIPKONIA ™Â ·˘Ù¿ Ù· ˘ÏÈο ·Ú·ÙËÚÂ›Ù·È ‰È¿¯˘ÛË ÎÚ˘ÛÙ¿ÏÏˆÓ ˙ÈÚÎÔÓ›·˜ ̤۷ Û ̛· ¿ÏÏË ÎÚ˘ÛÙ·ÏÏÈ΋ Ì‹ÙÚ·. E›Ó·È Ù· ÏÈÁfiÙÂÚÔ ÌÂÏÂÙË̤ӷ, ·ÏÏ¿ Î·È Ì ÌÈÎÚfiÙÂÚÔ ÂÌÔÚÈÎfi ÂӉȷʤÚÔÓ ÂÓÈÛ¯˘Ì¤Ó· ÎÂÚ·ÌÈο. X·Ú·ÎÙËÚÈÛÙÈο ·Ú·‰Â›ÁÌ·Ù· Â›Ó·È Ë ÂÓÈÛ¯˘Ì¤ÓË Ì ˙ÈÚÎÔÓ›· ·ÏÔ˘Ì›Ó· (Zirconia toughened alumina ‹ ZTA) Î·È Ô ÂÓÈÛ¯˘Ì¤ÓÔ˜ Ì ˙ÈÚÎÔÓ›· ÌÔ˘Ï›Ù˘ (3Al2O3.2SiO2 ‹ ZTM)31 Y¿Ú¯Ô˘Ó ‚¤‚·È· Î·È ¿Ú· ÔÏÏÔ› ¿ÏÏÔÈ Û˘Ó‰˘·ÛÌÔ› ˘ÏÈÎÒÓ ·ÏÔ˘Ì›Ó·˜ Î·È ˙ÈÚÎÔÓ›·˜, fiÔ˘ ÙÔ ÔÛÔÛÙfi Ù˘ ˙ÈÚÎÔÓ›·˜ Â›Ó·È ÌÂÁ·Ï‡ÙÂÚÔ ·fi ·˘Ùfi Ù˘ ·ÏÔ˘Ì›Ó·˜ ÔfiÙ ϤÔÓ ÚÔ·ÙÂÈ ÌÈ· ¿ÏÏË ÛÂÈÚ¿ ˘ÏÈÎÒÓ Ë ÂÓÈÛ¯˘Ì¤ÓË Ì ·ÏÔ˘Ì›Ó· Hellenic Stomatological Review 57: 101-137, 2013 EÈÎ. 4 : H ‰ËÌÈÔ˘ÚÁ›· ÔÒÓ Ô͢ÁfiÓÔ˘ (oxygen vacancies) ÙÔ˘ ÎÚ˘ÛÙ¿ÏÏÔ˘ Ù˘ ˘ÙÙÚ›·˜ ÛÙËÓ YSZ Û ΢‚È΋ ÎÚ˘ÛÙ·ÏÏÈ΋ ‰ÔÌ‹ Fig. 4: Oxygen vacancies of yttria crystal in cubic YSZ’s crystal www.wikipedia.org/wiki/yttria-stabilised_zirconia oxygen vacancies Fe +3, Ga +3, Y +3 b) tetravalent ions with smaller or larger atomic volume (Ti +4, Ce +4) c) compensation load impurities29. Considerable research has been done, however, in ceramics based on zirconia. Many different methods of synthesis and stabilization have been proposed and many oxides have beem tested suvh as magnesium, calcium, cerium and yttrium (MgO, CaO, CeO2, Y2O3) as well as rare earth oxides27. These new zirconia ceramics and specifically the partially stabilized zirconia (PSZ) were characterized by Garvie as “ceramic steel” because they show several similarities with steel as having three allotropic forms, martensinic type phase transformation and variable phases28. FORMS OF REINFORCED ZIRCONIA CERAMICS The term reinforced ceramics includes a wide class of materials and microstructures29. Reinforced zirconia is divided into three main categories. In the first two, materials consist of at least two phases with the t-phase to be the smallest one, while the third category includes primarily monophase t- zirconia29. Therefore we distinguish: 1. Zirconia reinforced ceramics, 2. Ceramics with partially stabilized tetragonal zirconia and 3. Ceramics with fully stabilized tetragonal zirconia. 1. ZIRCONIA REINFORCED CERAMICS In these materials zirconia crystals diffuseinto another crystal matrix. they are the least studied but with the less commercial interest reinforced ceramics. Typical examples are alumina reinforced with zirconia (Zirconia toughened alumina or ZTA) and zirconia reinforced mullite (3Al2O3.2SiO2 or ZTM)31. There are many other combinations of alumina and zirconia, where the proportion of zirconia is greater than that of alumina and constitute 107 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review ˙ÈÚÎÔÓ›· (AZT)28. T· Û˘ÁÎÂÎÚÈ̤ӷ ÎÂÚ·ÌÈο ÌÔÚÔ‡Ó Ó· ÏÂÈÙÔ˘ÚÁ‹ÛÔ˘Ó ˆ˜ ˘ÏÈο ·ÎfiÌ· Î·È ¯ˆÚ›˜ ÙËÓ ·ÚÔ˘Û›· οÔÈÔ˘ ÛÙ·ıÂÚÔÔÈËÙ‹ ηıÒ˜ Ë ÛÙ·ıÂÚfiÙËÙ· Ù˘ t-Ê¿Û˘ ÂϤÁ¯ÂÙ·È ·fi ÙÔ Ì¤ÁÂıÔ˜ ÙˆÓ ÎfiÎΈÓ, ÙË ÌÔÚÊÔÏÔÁ›· ÙÔ˘ Î·È ı¤ÛË ÙÔ˘ (ÂÚÈÎÚ˘ÛÙ·ÏÏÈο ‹ ÂÓ‰ÔÎÚ˘ÛÙ·ÏÏÈο)22. O˘ÛÈ·ÛÙÈο ÚfiÎÂÈÙ·È ÁÈ· ¤Ó· Ê·ÈÓfiÌÂÓÔ ·Ó¿ÏÔÁÔ Ù˘ ÌÂÙ·ÙfiÈÛ˘ ÙÔ˘ ıÂÚÌÔÎÚ·ÛÈ·ÎÔ‡ ‰È·ÛÙ‹Ì·ÙÔ˜ ¤Ó·Ú͢ Ù˘ Ì·ÚÙÂÓÛÈÙÈ΋˜ ÌÂÙ·ÙÚÔ‹˜ οو ·fi ÙË ıÂÚÌÔÎÚ·Û›· ‰ˆÌ·Ù›Ô˘31. H ÚÔÛı‹ÎË ˙ÈÚÎÔÓ›·˜ ÌÔÚ› Ó· Á›ÓÂÈ Â›Ù Û ÌÔÚÊ‹ ηı·Ú‹˜ ˙ÈÚÎÔÓ›·˜ ‹ ˆ˜ PSZ Û ÛÎfiÓË ·ÏÔ˘Ì›Ó·˜. M ·˘ÙfiÓ ÙÔÓ ÙÚfiÔ ÂÓÈÛ¯‡ÂÙ·È ÙfiÛÔ Ë ‰˘ÛıÚ·˘ÛÙfiÙËÙ· (Kic) fiÛÔ Î·È Ë ·ÓÙÔ¯‹ ο̄˘ ÙÔ˘ ˘ÏÈÎÔ‡, ·ÚΛ Ô ÎfiÎÎÔ˜ Ù˘ ηı·Ú‹˜ ˙ÈÚÎÔÓ›·˜ Ó· Â›Ó·È Ù˘ Ù¿Í˘ ÙˆÓ 1-2 Ìm Î·È Ù˘ ÌÂÚÈÎÒ˜ ÛÙ·ıÂÚÔÔÈË̤Ó˘ ˙ÈÚÎÔÓ›·˜ 2-5 Ìm Û ÔÛÔÛÙfi ¤ˆ˜ 15%32. TÔ ÔÚ҉˜ ÙˆÓ ÌÈÎÙÒÓ ÎÂÚ·ÌÈÎÒÓ ZTA ÊÙ¿ÓÂÈ ÙÔ 8-11% Î·È Â›Ó·È ÌÂÁ·Ï‡ÙÂÚÔ ÙˆÓ ÎÂÚ·ÌÈÎÒÓ ÌÂÚÈÎÒ˜ ÛÙ·ıÂÚÔÔÈË̤Ó˘ ÙÂÙÚ·ÁˆÓÈ΋˜ ˙ÈÚÎÔÓ›·˜ Ì ˘ÙÙÚ›· (Y-TZP). A˘Ùfi ÂÍËÁ› ÂÓ Ì¤ÚÂÈ Î·È ÙȘ ¯·ÌËÏfiÙÂÚ˜ Ì˯·ÓÈΤ˜ ·ÓÙÔ¯¤˜ Û ۯ¤ÛË Ì ÙËÓ ˙ÈÚÎÔÓ›· Y-TZP22. H ηٷÛ΢‹˜ ÎÂÚ·ÌÈÎÒÓ Ù¤ÙÔÈÔ˘ Ù‡Ô˘ Â›Ó·È ‰˘Ó·ÙfiÓ Ó· Á›ÓÂÈ Â›Ù Ì Ù¯ÓÈ΋ «slip-cast» ›Ù Ì ÂÎÙÚÔ¯ÈÛÌfi Û «Ì·Ï·Îfi ÛÙ¿‰ÈÔ» ÙÔ˘ ˘ÏÈÎÔ‡ (soft machining)23. T· ÎÂÚ·ÌÈο ZTA Ê·›ÓÔÓÙ·È ÔÏÏ¿ ˘ÔÛ¯fiÌÂÓ· ÁÈ· ‚ÈÔ˚·ÙÚÈΤ˜ ÂÊ·ÚÌÔÁ¤˜. EÏ¿¯ÈÛÙ· ›¯·Ó ‰ËÌÔÛÈ¢ı› ̤¯ÚÈ ÚfiÛÊ·Ù· ÁÈ· ÙË ¯Ú‹ÛË ÙÔ˘˜ ˆ˜ ÎÂÚ·ÌÈÎÒÓ ‚ÈÔ¸ÏÈÎÒÓ33. TÔ ÁÂÁÔÓfi˜ fï˜ fiÙÈ Ë ÚÔÛı‹ÎË ·ÏÔ˘Ì›Ó·˜ ÛÙË ˙ÈÚÎÔÓ›· ÂÌÔ‰›˙ÂÈ ÙË Á‹Ú·ÓÛË ÙÔ˘ ˘ÏÈÎÔ‡ ‹ ÙÔ˘Ï¿¯ÈÛÙÔÓ ÌÂÈÒÓÂÈ ‰Ú·ÛÙÈο ÙËÓ ÎÈÓËÙÈ΋ Ù˘ ı· Ú¤ÂÈ Ó· ‰›ÓÂÈ ÂÏ›‰Â˜ ÁÈ· ÙËÓ Î·Ù·Û΢‹ ÂÓfi˜ ÈÛ¯˘ÚÔ‡ ‚ÈÔ¸ÏÈÎÔ‡ ··ÏÏ·Á̤ÓÔ˘ ·fi ÙÔ Ê·ÈÓfiÌÂÓÔ Ù˘ Á‹Ú·ÓÛ˘14. §›Á˜ ¤Ú¢Ó˜ ¤¯Ô˘Ó Á›ÓÂÈ ÛÙÔ Ê·ÈÓfiÌÂÓÔ Ù˘ Á‹Ú·ÓÛ˘ ÙˆÓ Û˘ÛÙËÌ¿ÙˆÓ ·ÏÔ˘Ì›Ó·˜-˙ÈÚÎÔÓ›·˜. º·›ÓÂÙ·È fï˜ fiÙÈ ¤Ó· ÌÈÎÚfi ÔÛÔÛÙfi Á‹Ú·ÓÛ˘ ·Ú·ÙËÚÂ›Ù·È ·ÚfiÏ· ·˘Ù¿, ÂÍ·ÚÙÒÌÂÓÔ ·fi Ù· ¯·Ú·ÎÙËÚÈÛÙÈο ÌÈÎÚÔ‰ÔÌ‹˜ ÙˆÓ ‰‡Ô Ê¿ÛÂˆÓ ÙÔ˘ ˘ÏÈÎÔ‡34. ¶ÈÔ Û˘ÁÎÂÎÚÈ̤ӷ Ô ‚·ıÌfi˜ ÌÂÙ·ÙÚÔ‹˜ Ê¿Û˘ ÛÙ· ÎÂÚ·ÌÈο ZTA ÂÍ·ÚÙ¿Ù·È ·fi ÙË ıÂÚÌÔÎÚ·Û›·, ÙË ‰È¿ÚÎÂÈ· Î·È ÙËÓ ›ÂÛË Ô˘ ˘Ê›ÛÙ·Ù·È ÙÔ ˘ÏÈÎfi Î·È Â›Ó·È ·ÓÙÈÛÙÚfiʈ˜ ·Ó¿ÏÔÁÔ˜ ÙÔ˘ ÌÂÁ¤ıÔ˘˜ ÙÔ˘ ÎfiÎÎÔ˘35. TÔ ÏÂÔÓ¤ÎÙËÌ· Ù˘ ηχÙÂÚ˘ ·ÓÙ›ÛÙ·Û˘ ÛÙË Á‹Ú·ÓÛË Û‹ÌÂÚ· ·ÌÊÈÛ‚ËÙ›ٷÈ36. T· Û‡ÓıÂÙ· ÎÂÚ·ÌÈο ˘ÏÈο Ù‡Ô˘ ZTA ‰È·ÎÚ›ÓÔÓÙ·È Û ‰È¿ÊÔÚÔ˘˜ Ù‡Ô˘˜ ¤¯ÔÓÙ·˜ Ô Î·ı¤Ó·˜ ‰È·ÊÔÚÂÙÈ΋ Û‡ÓıÂÛË, ÔÛfi Î·È Â›‰Ô˜ ÛÙ·ıÂÚÔÔÈËÙ‹, ηıÒ˜ Î·È ÚÔÛı‹ÎË ¿ÏÏˆÓ ÔÍÂȉ›ˆÓ Î·È ÎÚ˘ÛÙ·ÏÏÈÎÒÓ Ê¿ÛˆÓ. EӉȷʤÚÔÓ Ê·›ÓÂÙ·È Ó· ¤¯ÂÈ Ë ZTA Ì ÚÔÛı‹ÎË ¯ÚˆÌ›·˜ (Cr2O3), Ë ÔÔ›· ÂÈÙ˘Á¯¿ÓÂÈ ·‡ÍËÛË Ù˘ ‰˘ÛıÚ·˘ÛÙfiÙËÙ·˜ ‰È·ÙËÚÒÓÙ·˜ ÛÙÔ ›‰ÈÔ Â›Â‰Ô ÙË ÛÎÏËÚfiÙËÙ· ÙÔ˘ ˘ÏÈÎÔ‡37. º·›ÓÂÙ·È Ì¿ÏÈÛÙ· fiÙÈ ÙÔ ˘ÏÈÎfi ·˘Ùfi ¤¯ÂÈ ‹‰Ë ·ÔÙÂϤÛÂÈ ·ÓÙÈΛÌÂÓÔ ÌÂϤÙ˘ ÁÈ· ÙË ¯Ú‹ÛË ÙÔ˘ ÛÙËÓ Ô‰ÔÓÙÈ·ÙÚÈ΋38. H Ù˘È΋ ÂÈÎfiÓ· ÙˆÓ ZTA Û ËÏÂÎÙÚÔÓÈÎfi ÌÈÎÚÔÛÎfiÈÔ ÂÚÈÏ·Ì‚¿ÓÂÈ ÙÔ˘˜ ÂÓÈÛ¯˘ÙÈÎÔ‡˜ t-ÎÚ˘ÛÙ¿ÏÏÔ˘˜ ˙ÈÚÎÔÓ›·˜ ‰ÈÂÛ·Ṳ́ÓÔ˘˜ Û ̋ÙÚ· ÎÚ˘ÛÙ¿ÏÏˆÓ ·ÏÔ˘Ì›Ó·˜. ™ÙËÓ Ô‰ÔÓÙÈ·ÙÚÈ΋ ¯ÚËÛÈÌÔÔÈÂ›Ù·È ÙÔ VITA In-Ceram® ZIRCONIA (VITA, Germany) ÙÔ ÔÔ›Ô ·ÔÙÂÏÂ›Ù·È ·fi 30% Á˘·Ï› Î·È 70% ÔÏ˘ÎÚ˘ÛÙ·ÏÏÈÎfi ÎÂÚ·ÌÈÎfi. TÔ ˙ÈÚÎfiÓÈÔ ˆ˜ ÛÙÔÈ¯Â›Ô ÙÔ˘ ÂÚÈÔ‰ÈÎÔ‡ ›Ó·Î· ·Ó‹ÎÂÈ ÛÙ· ̤ٷÏÏ· ÌÂٿوÛ˘ ÛÙËÓ IVB ÔÌ¿‰·. X·Ú·ÎÙËÚÈÛÙÈÎfi ·˘Ù‹˜ Ù˘ ÔÌ¿108 another group of materials ie the alumina reinforced zirconia (AZT). These ceramics can serve as materials even without the presence of a stabilizers, as as the stability of the t- phase is controlled by the grain size, morphology and location (inter- or intra-granularly)22. Essentially it is a phenomenon analogous to the displacement of the temperature range of the martensitic transformation starting below room temperature31. The addition of zirconia can be made either in the form of pure zirconia or PSZ alumina powder. In this way both the fracture toughness (Kic) and the flexural strength of the material are enhanced, provided that the grain size of the pure zirconia is 1-2 Ìm and that of the partially stabilized zirconia is 2-5 Ìm in proportion up to 15%32. The porosity of mixed ZTA ceramics reaches 8-11% and is higher in fully stabilized tetragonal zirconia ceramics with yttria (Y- TZP). This partly explains the lower mechanical strength with respect to zirconia Y-TZP22. The construction of the ceramic restoration may be either with “slip-cast” technique or milling in “green phase” of the material (soft machining)23. The ZTA ceramics seem promising material for biomedical purposes. Few issues have been published until recently for its use as a ceramic biomaterial33. Yet the fact that the addition of alumina in zirconia prevents aging of the material, or at least drastically reduces the kinetics, should give hope for a strong biomaterial aging free14. Few studies have been published on the phenomenon of aging in alumina-zirconia composites. However, it seems that a small percentage of aging observed, depends on the characteristics of the microstructure of the two phases of the material34. More particularly the degree of transformation in ZTA phases depends on the temperature, duration and pressure on the material and is inversely proportional to the grain size35. However, the advantage of higher resistance to aging today is questioned36. The ZTA composites are divided into several types having each a different composition, amount and type of stabilizer as well as the addition of other oxides and crystalline phases. Interest seems to have the cromia doped ZTA which achieves increased toughness while maintaining the same level of hardness of the material37. This material has already been studied for use in dentistry38. The typical image of ZTA ceramics with electron microscope includes the t- zirconia crystals dispersed in a matrix of alumina crystals. In-Ceram Zirconia (In-Ceram® ZIRCONIA, VITA, Germany) used in dentistry consists of 30% glass and 70 % zirconia polycrystalline alumina ceramic with a ratio of about 70:30 by volume. According to Chai et al, In Ceram Zirconia comes from adding 33 % partially stabilized zirconia with 12% CeO2 to 67% In Ceram alumina39. 2. CERAMICS WITH PARTIALLY STABILIZED ZIRCONIA (PSZ) This category is the most studied and exploited commercially. Features complex microstructure and magnesiastabilized materials are the strongest reinforced ceraHellenic Stomatological Review 57: 101-137, 2013 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review ‰·˜ Â›Ó·È fiÙÈ Ù· ÈfiÓÙ· ÙÔ˘˜ ÛÂ Û˘ÓËıÈṲ̂ÓË Î·Ù¿ÛÙ·ÛË ÔÍ›‰ˆÛ˘ ¤¯Ô˘Ó ÌÂÚÈο Û˘ÌÏËڈ̤ÓÔ ÙÔÓ ˘ÔÊÏÔÈfi d17. T· ÛÙÔȯ›· ÌÂٿوÛ˘ ¯ÚËÛÈÌÔÔÈÔ‡ÓÙ·È Û ÔÏÏ¿ ÎÚ¿Ì·Ù· Î·È Û˘¯Ó¿ Û¯ËÌ·Ù›˙Ô˘Ó ¤Á¯ÚˆÌ˜ ÂÓÒÛÂȘ. T· ¿ÙÔÌ¿ ÙÔ˘˜ ‰È·ı¤ÙÔ˘Ó Î¿ÔÈÔ ÌË Û˘ÌÏËڈ̤ÓÔ ÂÛˆÙÂÚÈÎfi ÊÏÔÈfi (ÛÙÈ‚¿‰·) Ô˘ ¤¯ÂÈ ÎÂÓ¤˜ ı¤ÛÂȘ ËÏÂÎÙÚÔÓ›ˆÓ. ™Â ıÂÚÌÔÎÚ·Û›· ÂÚÈ‚¿ÏÏÔÓÙÔ˜ ¤¯ÂÈ ÎÏÂÈÛÙ‹ ÂÍ·ÁˆÓÈ΋ ÎÚ˘ÛÙ·ÏÏÈ΋ ‰ÔÌ‹ Î·È Ê˘ÛÈΤ˜ Î·È ¯ËÌÈΤ˜ ȉÈfiÙËÙ˜ ·ÚfiÌÔȘ Ì ÙÔ ÙÈÙ¿ÓÈÔ18 Ì ·Ó·ÏÔÁ›· ÂÚ›Ô˘ 70:30 ηٿ fiÁÎÔ. O Chai ·Ó·Ê¤ÚÂÈ fiÙÈ ÙÔ ˘ÏÈÎfi In Ceram Zirconia ÚÔ¤Ú¯ÂÙ·È ·fi ÙËÓ ÚÔÛı‹ÎË 33% ÌÂÚÈÎÒ˜ ÛÙ·ıÂÚÔÔÈË̤Ó˘ ˙ÈÚÎÔÓ›·˜ Ì 12% CeO2 Û 67% In Ceram alumina39. 2. KEPAMIKA ME MEPIKø™ ™TA£EPO¶OIHMENH ZIPKONIA (PARTIALLY STABILIZED ZIRCONIA H PSZ) H ηÙËÁÔÚ›· ·˘Ù‹ Â›Ó·È Ë Ï¤ÔÓ ÌÂÏÂÙË̤ÓË Î·È ·ÍÈÔÔÈË̤ÓË ÂÌÔÚÈο. ¢È·ı¤ÙÂÈ ÔχÏÔÎË ÌÈÎÚÔ‰ÔÌ‹ Î·È ÛÙËÓ ÂÚ›ÙˆÛË ˘ÏÈÎÒÓ Ì ÛÙ·ıÂÚÔÔÈËÙ‹ Ì·ÁÓËÛ›· Â›Ó·È ·fi Ù· ÈÛ¯˘ÚfiÙÂÚ· ÂÓÈÛ¯˘Ì¤Ó· ÎÂÚ·ÌÈο23. ™Â ·˘Ù¿ Ù· ÎÂÚ·ÌÈο Ë ÙÂÙÚ·ÁˆÓÈ΋ t-Ê¿ÛË Û¯ËÌ·Ù›˙ÂÙ·È Û ̋ÙÚ· ÛÙ·ıÂÚÔÔÈË̤Ó˘ ΢‚È΋˜ c-Ê¿Û˘. A˘Ùfi ÂÈÙ˘Á¯¿ÓÂÙ·È Ì ÚÔÛÌ›ÍÂȘ ‰È¿ÊÔÚˆÓ ÔÍÂȉ›ˆÓ (CaO, MgO, La2O3, Y2O3) ÛÂ Û˘ÁÎÂÓÙÚÒÛÂȘ ¯·ÌËÏfiÙÂÚ˜ ·fi ·˘Ù¤˜ Ô˘ ¯ÚÂÈ¿˙ÔÓÙ·È ÁÈ· ÙËÓ Ï‹ÚË ÛÙ·ıÂÚÔÔ›ËÛË Ù˘ ΢‚È΋˜ Ê¿Û˘. ŒÙÛÈ Ë t-Ê¿ÛË ‚Ú›ÛÎÂÙ·È ˆ˜ ›˙ËÌ· ÛÙÔ ÂÛˆÙÂÚÈÎfi ÙˆÓ ÎfiÎÎˆÓ Ì¤Û· Û ÌÈ· Ì‹ÙÚ· c-ÛÙ·ıÂÚÔÔÈË̤Ó˘ Ê¿Û˘. H t-Ê¿ÛË Â›Ó·È Û ϋÚË Û˘ÓÔ¯‹ Ì ÙÔ˘˜ ΢‚ÈÎÔ‡˜ ÎÚ˘ÛÙ¿ÏÏÔ˘˜ Î·È ¤¯ÂÈ ÌÔÚÊ‹ ·ÙÚ·ÎÙÔÂȉ‹ ÛÂ Â›Â‰Ô Ó·ÓÔ̤ÙÚˆÓ. ¶ÈÔ ·Ï¿ Ù· ÎÂÚ·ÌÈο ·˘Ù¿ Û ıÂÚÌÔÎÚ·Û›· ‰ˆÌ·Ù›Ô˘ Â›Ó·È ÔÏ˘Ê·ÛÈο Î·È ÂÚÈÏ·Ì‚¿ÓÔ˘Ó Û ÌÈÎÚ‹ Û˘ÁΤÓÙÚˆÛË ÌÔÓÔÎÏÈÓ‹ Î·È ÙÂÙÚ·ÁˆÓÈ΋ Ê¿ÛË Û ˘fiÛÙڈ̷ ÛÙ·ıÂÚÔÔÈË̤Ó˘ ΢‚È΋˜ ˙ÈÚÎÔÓ›·˜. A˘Ù‹ Ë ÌÂÙ·ÛÙ·ı‹˜ ηٿÛÙ·ÛË Ù˘ t-Ê¿Û˘ ‰È·ÙËÚÂ›Ù·È ¯¿ÚË ÛÙËÓ ·ÚÔ˘Û›· ÙˆÓ ÛÙ·ıÂÚÔÔÈËÙÒÓ. H ÌÂÙ·ÙÚÔ‹ Ù˘ Û m-Ê¿ÛË, Ë ÔÔ›· ı· Ô‰ËÁÔ‡Û Û ·‡ÍËÛË fiÁÎÔ˘ ÙÔ˘ ˘ÏÈÎÔ‡ ÂÌÔ‰›˙ÂÙ·È ·fi ÙȘ Û˘ÌÈÂÛÙÈΤ˜ Ù¿ÛÂȘ Ô˘ ·ÛÎÔ‡ÓÙ·È Û ·˘ÙÔ‡˜ ÙÔ˘˜ ÎfiÎÎÔ˘˜ ·fi ÙÔ˘˜ ÁÂÈÙÔÓÈÎÔ‡˜ ÙÔ˘˜40. T· ‰È·ÁÚ¿ÌÌ·Ù· Ê¿ÛÂˆÓ ‰Â›¯ÓÔ˘Ó Ì›· Ì›ÍË Î˘‚È΋˜, ÙÂÙÚ·ÁˆÓÈ΋˜ ‹ Î·È ÌÔÓÔÎÏÈÓÔ‡˜ Ê¿Û˘ Î·È ÁÈ· Ó· ·Ú·¯ı› ÌÈ· ÌÂÚÈÎÒ˜ ÛÙ·ıÂÚÔÔÈË̤ÓË ˙ÈÚÎÔÓ›· (PSZ) ¯ÚÂÈ¿˙ÔÓÙ·È ‰‡Ô ÚÔ¸Ôı¤ÛÂȘ. K·Ù·Ú¯‹Ó Ë Û˘ÁΤÓÙÚˆÛË ÙÔ˘ ÛÙ·ıÂÚÔÔÈËÙ‹ Ó· Â›Ó·È ÌÈÎÚfiÙÂÚË ·fi fiÛË ¯ÚÂÈ¿˙ÂÙ·È ÁÈ· ÙËÓ Ï‹ÚË ÛÙ·ıÂÚÔÔ›ËÛË Ù˘ ΢‚È΋˜ Ê¿Û˘ Î·È Î·Ù¿ ‰Â‡ÙÂÚÔÓ Ë Î˘‚È΋ Ê¿ÛË Ó· ıÂÚÌ·Óı› ÒÛÙ ӷ ·Ó·Ù˘¯ı› ¤Ó· ‰ÈÊ·ÛÈÎfi ÎÂÚ·ÌÈÎfi32. H PSZ ¯·Ú·ÎÙËÚ›ÛÙËΠ·fi ÙÔ˘˜ Garvie Î·È Nicholson28 ˆ˜ «ÎÂÚ·ÌÈÎfi˜ ¯¿Ï˘‚·˜» ·ÊÔ‡ ·Ú·Ù‹ÚËÛ·Ó fiÙÈ ÚfiÎÂÈÙ·È ÁÈ· ˘ÏÈÎfi ˘„ËÏ‹˜ Ì˯·ÓÈ΋˜ ·ÓÙÔ¯‹˜ Î·È ÛÎÏËÚfiÙËÙ·˜ Ì ÙÔ ÌÔÓ·‰ÈÎfi ¯·Ú·ÎÙËÚÈÛÙÈÎfi Ù˘ ÂÓ›Û¯˘Û‹˜ ÙÔ˘ ·fi ÙË ÌÂÙ·ÙÚÔ‹ Ê¿Û˘ (Transformation toughening). H ÌÔÓ·‰È΋ ·˘Ù‹ ȉÈfiÙËÙ· «ÌÂÙ·ÛÙ¿ıÂÈ·» Â›Ó·È ‰˘Ó·ÙfiÓ Ó· ¯·ı› fiÙ·Ó ÔÈ ÎfiÎÎÔÈ Â›Ó·È Ôχ ÌÈÎÚÔ›, ÔfiÙ ‰ÂÓ ÌÂÙ·ÙÚ¤ÔÓÙ·È, ηıÒ˜ Î·È fiÙ·Ó Â›Ó·È Ôχ ÌÂÁ¿ÏÔÈ, ‰Â ‰È·ÙËÚÔ‡ÓÙ·È ˆ˜ ÌÂÙ·ÙÚÂfiÌÂÓÔÈ ÎÚ‡ÛÙ·ÏÏÔÈ, ÁÈ·Ù› ηı›ÛÙ·ÓÙ·È ‰˘Ó·Ù¤˜ ·˘ÙfiÌ·Ù˜ ÌÂÙ·ÙÚÔ¤˜ ÙÔ˘˜ Û ÌÔÓÔÎÏÈÓ‹ Ê¿ÛË Î·Ù¿ ÙËÓ „‡ÍË ÙÔ˘˜ Û ıÂÚÌÔÎÚ·Û›· ‰ˆÌ·Ù›Ô˘41, 42. I‰È·›ÙÂÚË ÚÔÛÔ¯‹ ¯ÚÂÈ¿˙ÂÙ·È Û ‰‡Ô ‚·ÛÈο ÛÙ¿‰È· ·Hellenic Stomatological Review 57: 101-137, 2013 mics23. In these ceramics t-phase is formed in the matrix of stabilized cubic c-phase. This is achieved with blends of various oxides (CaO, MgO, La2O3, Y2O3) at concentrations lower than those needed to fully stabilize the cubic phase. Thus, the t- phase is precipitated inside the grains in a matrix c- stationary phase. T-phase is fully consistent with the cubic crystals and has a fusiform shape at nanometer level. Simply these ceramics at room temperature are multiphasic and include a short concentration of monoclinic and tetragonal phase in cubic stabilized zirconia substrate. This metastable state of the t- phase is maintained thanks to the presence of stabilizers. The transformation to the m- phase which would increase the volume of the material is prevented by the compressive stresses exerted on those grains from the adjacent ones40.The phase diagrams show a mixing of cubic, tetragonal or monoclinic phase. To produce a partially stabilized zirconia (PSZ) two conditions are needed. First, the concentration of the stabilizer should be less than needed to fully stabilize the cubic phase and, secondly, the cubic phase should be heated to develop a biphasic ceramic32. PSZ was characterized by Garvie and Nicholson as “ceramic steel”, since it was observed that this material is of high mechanical strength and toughness with the unique characteristics coming from the phase transformation (Transformation toughening). This unique property (metastability) may be lost when the grains are very small, so they do not transform, and when they are too large, so they are not stable as converted crystals, because they automatically convert to monoclinic phase during cooling to ambient room temperature41, 42. Particular care is needed in two main production steps of such ceramics. First of all sintering must be carried out at high temperatures (1680ÆC and 1800ÆC) and then the velocity and the temperature range time of cooling cycles must be tightly controlled. During the cooling step, at about 1100ÆC, the tetragonal phase is developed, whose volume fraction is decisive for the break strength of the material31, 43. There are two main types of partially stabilized zirconia (PSZ) according to stabilizers and microstructure. The first is a coarse structure containing 8% MgO and grain size of 50-100 Ìm and is called Mg-PSZ. The second by adding Y2O3 leading to a very fine ceramic structure with a grain size <1Ìm. A commercial brand for Mg-PSZ is Denzir-M (Dentronic AB, Sweden)44. Two main disadvantages of Denzir are the porosity and the large grain size (30-60 Ìm) which makes the material unsuitable for biomedical purposes, as well as the presence of impurities such as SiO2 which reduce the magnesium content of Mg (through the creation of Mg-silicates) and spontaneous cause aging of the material (t->m transformation)22. 3. YTTRIUM STABILIZED TETRAGONAL ZIRCONIA (TZP) POLYCRYSTALS, Y-TZP AND CERIA STABILIZED TETRAGONAL ZIRCONIA POLYCRYSTALS, Ce-TZP) These constitute the single phase polycrystalline t-zirco109 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review Ú·ÁˆÁ‹˜ Ù¤ÙÔÈÔ˘ ›‰Ô˘˜ ÎÂÚ·ÌÈÎÒÓ. ¶ÚÒÙ· ·fi fiÏ· Ë ˘ÚÔÛ˘Ûۈ̿وÛË Ú¤ÂÈ Ó· Ú·ÁÌ·ÙÔÔÈÂ›Ù·È Û ˘„ËϤ˜ ıÂÚÌÔÎڷۛ˜ (1680ÆC Î·È 1800ÆC) Î·È ÛÙË Û˘Ó¤¯ÂÈ· Ë Ù·¯‡ÙËÙ· Î·È Ù· ıÂÚÌÔÎÚ·Ûȷο ‰È·ÛÙ‹Ì·Ù· ÙÔ˘ ·ÎÏÔ˘ „‡Í˘ Ú¤ÂÈ Ó· ÂϤÁ¯ÔÓÙ·È ·˘ÛÙËÚ¿. K·Ù¿ ÙÔ ÛÙ¿‰ÈÔ Ù˘ „‡Í˘, Á‡Úˆ ÛÙÔ˘˜ 1100ÆC, ·Ó·Ù‡ÛÛÂÙ·È Ë ÙÂÙÚ·ÁˆÓÈ΋ Ê¿ÛË, Ù˘ ÔÔ›·˜ ÙÔ ÎÏ¿ÛÌ· Û fiÁÎÔ Â›Ó·È Î·ıÔÚÈÛÙÈÎfi ÁÈ· ÙËÓ ·ÓÙÔ¯‹ ıÚ·‡Û˘ ÙÔ˘ ˘ÏÈÎÔ‡30, 43. ¢‡Ô Â›Ó·È ÔÈ Î‡ÚÈÔÈ Ù‡ÔÈ ÌÂÚÈÎÒ˜ ÛÙ·ıÂÚÔÔÈË̤Ó˘ ˙ÈÚÎÔÓ›·˜ (PSZ) ·Ó¿ÏÔÁ· Ì ÙÔ˘˜ ÛÙ·ıÂÚÔÔÈËÙ¤˜ Î·È ÙË ÌÈÎÚÔ‰ÔÌ‹ ÙÔ˘˜. O ÚÒÙÔ˜ Ì ·‰ÚfiÎÔÎÎË ‰ÔÌ‹ Â›Ó·È Ì ÂÚÈÂÎÙÈÎfiÙËÙ· 8% MgO Î·È Ì¤ÁÂıÔ˜ ÎfiÎÎÔ˘ 50-100 Ìm Î·È ÔÓÔÌ¿˙ÂÙ·È Mg-PSZ. O ‰Â‡ÙÂÚÔ˜ Ì ÚÔÛı‹ÎË Y2O3 Ô˘ Ô‰ËÁ› Û ˘ÂÚÏÂÙfiÎÔÎη ÎÂÚ·ÌÈο Ì ̤ÁÂıÔ˜ ÎfiÎÎÔ˘ <1Ìm. ŒÓ· ÂÌÔÚÈÎfi Û··ÛÌ· ˙ÈÚÎÔÓ›·˜ MgPSZ Â›Ó·È ÙÔ Denzir-M (Dentronic AB, Sweden)44. ¢‡Ô Â›Ó·È Ù· ‚·ÛÈο ÚÔ‚Ï‹Ì·Ù· ÙˆÓ ˘ÏÈÎÒÓ: ·)ÙÔ ÔÚ҉˜ Î·È ‚) ÙÔ ÌÂÁ¿ÏÔ Ì¤ÁÂıÔ˜ ÎfiÎÎÔ˘ (30-60 Ìm) Ù· ÔÔ›· ÌÔÚ› Ó· ÚÔηϤÛÔ˘Ó ·ÏÏÔ›ˆÛË ˘ÏÈÎÔ‡ ÒÛÙ ӷ Â›Ó·È ·Î·Ù¿ÏÏËÏÔ Ï¤ÔÓ Û ‚ÈÔ˚·ÙÚÈΤ˜ ÂÊ·ÚÌÔÁ¤˜. E›Û˘ Ë ·ÚÔ˘Û›· ÚÔÛÌ›ÍÂˆÓ SiO2 ÔÈ Ôԛ˜ ÌÂÈÒÓÔ˘Ó ÙËÓ ÂÚÈÂÎÙÈÎfiÙËÙ· Û ̷ÁÓ‹ÛÈÔ Mg (Ì ÙË ‰ËÌÈÔ˘ÚÁ›· ˘ÚÈÙÈÎÒÓ ÂÓÒÛÂˆÓ ÙÔ˘ Mg) Î·È ÚÔηÏÔ‡Ó ·˘ıfiÚÌËÙË Á‹Ú·ÓÛË ÙÔ˘ ˘ÏÈÎÔ‡ (t-m transformation)22. 3. KPY™TA§§OI TETPA°øNIKH™ ZIPKONIA™ (YTTRIUM STABILIZED TETRAGONAL ZIRCONIA POLYCRYSTALS, Y-TZP AND CERIA STABILIZED TETRAGONAL ZIRCONIA POLYCRYSTALS, Ce-TZP) T· ÎÂÚ·ÌÈο ·˘Ù‹˜ Ù˘ ηÙËÁÔÚ›·˜ ·ÔÙÂÏÔ‡ÓÙ·È ·fi ÌÔÓÔÊ·ÛÈ΋ ÔÏ˘ÎÚ˘ÛÙ·ÏÏÈ΋ t-˙ÈÚÎÔÓ›· Î·È ‹‰Ë ·fi ÙÔ 1977 ÁÓÒÚÈ˙·Ó fiÙÈ Ì ÌÈÎÚ¤˜ Û˘ÁÎÂÓÙÚÒÛÂȘ ˘ÙÙÚ›Ô˘ ÌÔÚ› Ó· ηٷÛ΢·ÛÙ› ÌÈÎÚfiÎÔÎÎË ˙ÈÚÎÔÓ›· Î·È Ó· ÂÚȤ¯ÂÈ ¤ˆ˜ Î·È 98% t- Ê¿ÛË. H ˘„ËÏ‹ ·ÓÙÔ¯‹ (700 MPa ÛÙËÓ Î¿Ì„Ë) Û˘Ì›ÙÂÈ Ì ˘„ËÏfi ÔÛÔÛÙfi ÙÂÙÚ·ÁˆÓÈ΋˜ Ê¿Û˘ Î·È Ë ¯·ÌËÏ‹ (50-100 MPa) Ì ·ÓÙ›ÛÙÔȯ· ˘„ËÏfi ÔÛÔÛÙfi ÌÔÓÔÎÏÈÓÔ‡˜ Ê¿Û˘45. OÈ Ì¤ÁÈÛÙ˜ ÙÈ̤˜ ·ÓÙÔ¯‹˜ ÂÌÊ·Ó›˙ÔÓÙ·È fiÙ·Ó ÙÔ ÎÚ›ÛÈÌÔ Ì¤ÛÔ Ì¤ÁÂıÔ˜ ÎfiÎÎÔ˘ Â›Ó·È ÌÈÎÚfiÙÂÚÔ ÙÔ˘ 0,3 Ìm46. K¿Ùˆ ·fi ÙÔ 0,2 Ìm ÌÂÁ¤ıÔ˘˜ ÎfiÎÎÔ˘ ‰ÂÓ Â›Ó·È ‰˘Ó·Ùfi˜ Ô ÌÂÙ·Û¯ËÌ·ÙÈÛÌfi˜ Ê¿ÛÂˆÓ Î·È Û˘ÓÂÒ˜ ¤¯Ô˘Ì ¯·ÌËÏfiÙÂÚË ‰˘ÛıÚ·˘ÛÙfiÙËÙ·23. TÔ ÔÛÔÛÙfi Ù˘ ÙÂÙÚ·ÁˆÓÈ΋˜ Ê¿Û˘ Ô˘ ‰È·ÙËÚÂ›Ù·È Û ıÂÚÌÔÎÚ·Û›· ‰ˆÌ·Ù›Ô˘ ÂÍ·ÚÙ¿Ù·È ·fi ÙË ıÂÚÌÔÎÚ·Û›· ·Ú·Û΢‹˜, ÙÔ ÔÛÔÛÙfi ÙÔ˘ ÛÙ·ıÂÚÔÔÈËÙ‹ (Y2O3, CeO2), ÙÔ Ì¤ÁÂıÔ˜ ÙˆÓ ÎfiÎÎˆÓ Î·ıÒ˜ Î·È ÙÔ ‚·ıÌfi Ù˘ Û˘Ì›ÂÛ˘ Ô˘ ÂÍ·ÛÎÂ›Ù·È Û ·˘ÙÔ‡˜ ·fi ÙÔ Ï¤ÁÌ·23. OÈ Ì˯·ÓÈΤ˜ ȉÈfiÙËÙ˜ ÙˆÓ TZP ÂÍ·ÚÙÒÓÙ·È ·fi ·˘Ù¤˜ ÙȘ ·Ú·Ì¤ÙÚÔ˘˜7. ™Ù· ÎÂÚ·ÌÈο 3Y-TZP (3mol% Y2O3) Ô˘ ¯ÚËÛÈÌÔÔÈÔ‡ÓÙ·È ÛÙË Ô‰ÔÓÙÈ·ÙÚÈ΋, ÛËÌ·ÓÙÈÎfiÙÂÚÔ ÚfiÏÔ ÛÙȘ Ì˯·ÓÈΤ˜ ȉÈfiÙËÙ˜ ¤¯ÂÈ ÙÔ Ì¤ÁÂıÔ˜ ÙˆÓ ÎfiÎΈÓ23. ¶¤Ú·Ó ÂÓfi˜ ÎÚ›ÛÈÌÔ˘ ÌÂÁ¤ıÔ˘˜ ÎfiÎÎÔ˘, Ô˘ ΢ڛˆ˜ ÂÍ·ÚÙ¿Ù·È ·fi ÙË Û˘ÁΤÓÙÚˆÛË ÔÍÂȉ›Ô˘ ÙÔ˘ ˘ÙÙÚ›Ô˘ (Y2O3), Ú·ÁÌ·ÙÔÔÈÂ›Ù·È ·˘ÙfiÌ·ÙË ÌÂÙ·ÙÚÔ‹ ·fi ÙÂÙÚ·ÁˆÓÈ΋ Û ÌÔÓÔÎÏÈÓ‹ Ê¿ÛË. H ÌÂÙ·ÙÚÔ‹ ·ÚÂÌÔ‰›˙ÂÙ·È Û Ôχ ÏÂÙfiÎÔÎΘ ‰Ô̤˜. EÏ¿ÙÙˆÛË ÙÔ˘ ÌÂÁ¤ıÔ˘˜ ÙˆÓ ÎfiÎÎˆÓ ‹ ·‡ÍËÛË Ù˘ Û˘ÁΤÓÙÚˆÛ˘ ÙˆÓ ÛÙ·ıÂÚÔÔÈËÙÈÎÒÓ ÔÍÂÈ110 nia ceramics. Since 1977 it was found that adding small concentrations of yttrium on zirconia powder micrograin zirconia material can be produced, containing up to 98% t- phase. The high strength (700 MPa flexural strength) coincides with high tetragonal phase and the low one (50100 MPa) with high amount of monoclinic phase45. The maximum strength values occur when the critical average grain size is less than 0.3Ìm46. Below 0.2 Ìm grain size phase transformation is not possible and fracture toughness is lowered22. The proportion of the tetragonal phase at room temperature depends on the preparation temperature, the percentage of stabilizers (Y2O3, CeO2), the grain size and the degree of compression exerted on them by the grid22. The mechanical properties of TZP depend on these parameters7. In 3Y- TZP (3mol% Y2O3) used in dentistry, grain size plays the most important role in mechanical properties22. Beyond a critical grain size, which mainly depends on the concentration of yttrium dioxide, an automatic transformation from tetragonal to monoclinic phase can be observed. The conversion is restricted in very fine structures. Reduction in the grain size or increasing the concentration of the stabilizing oxides may reduce the transformation rate. Specifically drastic reduction in the grain size results in loss of metastability while increasing the concentration of the stabilizing oxide more than 3,5% Y2O3 in Y-TZP probably allow nucleation of stable cubic phase. Therefore in order to achieve a metastable tetragonal phase at room temperature, the grain size must be less than 0.8 Ìm and the proportion of the stabilizer oxide not exceeding 3mol%45. Also the sintering conditions affect both the stability and the final strength of the final product since they determine the grain size47. It appears that changing the sintering conditions from 1550ÆC to 1450ÆC develops cubic phase which reduces Y from the adjacent crystals, causing nucleation of t-m transformation sites and dramatically reduces the resistance to aging of the material48. A feature of Y-TZP ceramics is the formation of compressive layers on their surface. Tetragonal surface granules are not limited by the crystal matrix and therefore can be converted automatically into monoclinic because of the abrasive procedures provoking compressive stresses at a depth of some microns in the subsurface. This surface hardening and transformation phase plays a role in improving the mechanical properties and wear resistance of the material, but the thickness of the converted surface limits them. This phenomenon can be disastrous in the mechanical behavior of the material, if the conversion phase on the surface causes a surface cracking, followed by detachment of surface grains and proceed to the bulk of the material7. Many factors play a role in controlling the mechanical behavior of Y-TZP ceramics. The size and shape of the grains, the type and amount of stabilizer, the size and distribution of the internal stresses and the presence of residual stresses (prestresses)49. One of the disadvantages of 3Y-TZP ceramics is the sensitivity to thermal shocks. In such case there is depletion of yttrium from Hellenic Stomatological Review 57: 101-137, 2013 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review ‰›ˆÓ Â›Ó·È ‰˘Ó·ÙfiÓ Ó· ÂÏ·ÙÙÒÛÂÈ ÙÔ Ú˘ıÌfi ÌÂÙ·ÙÚÔ‹˜. ™˘ÁÎÂÎÚÈ̤ӷ ‰Ú·ÛÙÈ΋ Ì›ˆÛË ÙÔ˘ ÌÂÁ¤ıÔ˘˜ ÙˆÓ ÎfiÎÎˆÓ Ô‰ËÁ› Û ·ÒÏÂÈ· Ù˘ «ÌÂÙ·ÛÙ·ıÂÚfiÙËÙ·˜» ÂÓÒ ·‡ÍËÛË Ù˘ Û˘ÁΤÓÙÚˆÛ˘ ÙˆÓ ÛÙ·ıÂÚÔÔÈËÙÈÎÒÓ ÔÍÂȉ›ˆÓ ¿Óˆ ·fi 3,5% Y2O3 ÛÙÔ Y-TZP Èı·ÓÒ˜ Ó· ÂÈÙÚ¤„ÂÈ ‰ËÌÈÔ˘ÚÁ›· ˘Ú‹ÓˆÓ ÛÙ·ıÂÚ‹˜ ΢‚È΋˜ Ê¿Û˘. EÔ̤ӈ˜ ÚÔÎÂÈ̤ÓÔ˘ Ó· ÂÈÙ¢¯ı› ÙÂÙÚ·ÁˆÓÈ΋ ÌÂÙ·ÛÙ·ı‹˜ Ê¿ÛË Û ıÂÚÌÔÎÚ·Û›· ‰ˆÌ·Ù›Ô˘, ÙÔ Ì¤ÁÂıÔ˜ ÙˆÓ ÎfiÎÎˆÓ Ú¤ÂÈ Ó· Â›Ó·È ÌÈÎÚfiÙÂÚÔ ·fi 0,8 Ìm Î·È ÙÔ ÔÛÔÛÙfi ÙÔ˘ ÛÙ·ıÂÚÔÔÈËÙÈÎÔ‡ ÔÍÂȉ›Ô˘ Ó· ÌËÓ ÍÂÂÚÓ¿ Ù· 3mol%.45. E›Û˘ ÔÈ Û˘Óı‹Î˜ ˘ÚÔÛ˘Ûۈ̿وÛ˘ ÂËÚ¿˙Ô˘Ó ÙfiÛÔ ÙË ÛÙ·ıÂÚfiÙËÙ· fiÛÔ Î·È ÙËÓ ÙÂÏÈ΋ ·ÓÙÔ¯‹ ÙÔ˘ ÙÂÏÈÎÔ‡ ÚÔ˚fiÓÙÔ˜, ηıÒ˜ ηıÔÚ›˙Ô˘Ó ÙÔ Ì¤ÁÂıÔ˜ ÙˆÓ ÎfiÎΈÓ47. º·›ÓÂÙ·È fiÙÈ ÛÂ Û˘Óı‹Î˜ ˘ÚÔÛ˘Ûۈ̿وÛ˘ 1550ÆC ·ÓÙ› ÁÈ· 1450ÆC ·Ó·Ù‡ÛÛÂÙ·È Î˘‚È΋ Ê¿ÛË Ë ÔÔ›· ÌÂÈÒÓÂÈ ÙÔ Y ·fi ÙÔ˘˜ ÁÂÈÙÔÓÈÎÔ‡˜ ÎÚ˘ÛÙ¿ÏÏÔ˘˜, ÚÔηÏ› ˘Ú‹Ó˜ ÌÂÙ·ÙÚÔ‹˜ t-m ÌÂÈÒÓÔÓÙ·˜ ‰Ú·Ì·ÙÈο ÙËÓ ·ÓÙ›ÛÙ·ÛË ÙÔ˘ ˘ÏÈÎÔ‡ ÛÙË Á‹Ú·ÓÛË48. X·Ú·ÎÙËÚÈÛÙÈÎfi ÙˆÓ ÎÂÚ·ÌÈÎÒÓ Y-TZP Â›Ó·È Ô Û¯ËÌ·ÙÈÛÌfi˜ ıÏÈÙÈÎÒÓ ˙ˆÓÒÓ ÛÙËÓ ÂÈÊ¿ÓÂÈ¿ ÙÔ˘˜. OÈ ÂÈÊ·ÓÂÈ·ÎÔ› ÙÂÙÚ·ÁˆÓÈÎÔ› ÎfiÎÎÔÈ ‰ÂÓ ÂÚÈÔÚ›˙ÔÓÙ·È ·fi ÙÔ Ï¤ÁÌ· Î·È ÁÈ· ÙÔ ÏfiÁÔ ·˘Ùfi ÌÔÚÔ‡Ó Ó· ÌÂÙ·ÙÚ·Ô‡Ó ·˘ÙÔÌ¿Ùˆ˜ Û ÌÔÓÔÎÏÈÓ›˜ ÂÍ·ÈÙ›·˜ ·ÔÙÚÈÙÈÎÒÓ ‰È·‰ÈηÛÈÒÓ Ô˘ ÚÔηÏÔ‡Ó ıÏÈÙÈΤ˜ Ù¿ÛÂȘ Û ‚¿ıÔ˜ ÔÚÈÛÌ¤ÓˆÓ Ìm ˘ÔÂÈÊ·ÓÂȷο. A˘Ù‹ Ë ÂÈÊ·ÓÂȷ΋ ÌÂÙ·ÙÚÔ‹ Ê¿ÛÂˆÓ Î·È ÛÎÏ‹Ú˘ÓÛË ·›˙ÂÈ ÚfiÏÔ ÛÙË ‚ÂÏÙ›ˆÛË ÙˆÓ Ì˯·ÓÈÎÒÓ È‰ÈÔÙ‹ÙˆÓ Î·È Ù˘ ·ÓÙ›ÛÙ·Û˘ ÛÙË ÊıÔÚ¿ ÙÔ˘ ˘ÏÈÎÔ‡, ÙÔ ¿¯Ô˜ fï˜ Ù˘ ÌÂÙ·Ùڷ›۷˜ ÂÈÊ¿ÓÂÈ·˜ ÙȘ ÂÚÈÔÚ›˙ÂÈ. TÔ Ê·ÈÓfiÌÂÓÔ ·˘Ùfi ÌÔÚ› Ó· ·Ô‚› ηٷÛÙÚÔÊÈÎfi ÛÙË Ì˯·ÓÈ΋ Û˘ÌÂÚÈÊÔÚ¿ ÙÔ˘ ˘ÏÈÎÔ‡, ·Ó Ë ÌÂÙ·ÙÚÔ‹ Ê¿ÛÂˆÓ ÛÙËÓ ÂÈÊ¿ÓÂÈ· ÚÔηϤÛÂÈ ÌÈ· ÂÈÊ·ÓÂȷ΋ ÚˆÁÌ‹, ·ÎÔÏÔ˘ıÔ‡ÌÂÓË ·fi ·fiÛ·ÛË ÂÈÊ·ÓÂÈ·ÎÒÓ ÎfiÎÎˆÓ Î·È ÚÔ¯ˆÚ‹ÛÂÈ ÛÙË Ì¿˙· ÙÔ˘ ˘ÏÈÎÔ‡7. ¶ÔÏÏÔ› ·Ú¿ÁÔÓÙ˜ ÂϤÁ¯Ô˘Ó ÙË Ì˯·ÓÈ΋ Û˘ÌÂÚÈÊÔÚ¿ ÙˆÓ ÎÂÚ·ÌÈÎÒÓ Y-TZP. TÔ Ì¤ÁÂıÔ˜ Î·È Û¯‹Ì· ÙÔ˘ ÎfiÎÎÔ˘, Ô Ù‡Ô˜ Î·È ÙÔ ÔÛfi ÙÔ˘ ÛÙ·ıÂÚÔÔÈËÙ‹, ÙÔ Ì¤ÁÂıÔ˜ Î·È Ë Î·Ù·ÓÔÌ‹ ÙˆÓ ÂÛˆÙÂÚÈÎÒÓ Ù¿ÛÂˆÓ Î·È Ë ·ÚÔ˘Û›· ÙˆÓ ˘ÔÏÂÈÌÌ·ÙÈÎÒÓ Ù¿ÛˆÓ49. ŒÓ· ·fi Ù· ÌÂÈÔÓÂÎÙ‹Ì·Ù· ÙˆÓ ÎÂÚ·ÌÈÎÒÓ Y-TZP Â›Ó·È Ë Â˘·ÈÛıËÛ›· ÛÙÔ˘˜ ıÂÚÌÈ- grain boundaries resulting in cubic phase appearance which affects the consistency of the material. To address the phenomenon it was proposed the reduction of the grain size to nanometer scale and the addition of other stabilizers in order to improve its performance. It has been proposed that adding Cerium (Ce) and Alumina another Ce- stabilized alumina TZP ceramic can be created49. The fully stabilized zirconia is less elastic than the partially stabilized and less resistant to thermal shocks from MgPSZ. At temperatures above 900ÆC is prone to deformation50. One major limitation of Y-TZP in their use in dentistry concerns the optical properties and especially the opacity and the intense white color. For this reason, various additive oxides have been tested in order to change the color of Y-TZP. It seems that the addition of CeO2 and ErO2 improves the color without significantly affecting the mechanical properties51. Indeed the system Procera AllZirkon (Nobel Biocare) has four different colors. Recently new systems are developed with transparent zirconia (grain size 3nm) made with a particular zirconium, yttrium and oxygen ions condensation technique, in a gaseous phase. This kind of material is designed for the fabrication of full contour zirconia restorations without the need of a veneering material. 3.1. PHYSICAL PROPERTIES OF YTZP The properties of YTZP are dependent on yttria percentage and on grain size. The density of YTZP is 6.056.07 gr/cm3, and thermal conductivity of 2.2W /m*K32. The resistance to thermal shocks is approaching 400ÆC, and the dielectric constant from 16 to 18. It has zero porosity, white color and a maximum working temperature of 1500ÆC. The melting point is extremely high (2750ÆC). Coefficient of thermal expansion is 10,3*10-6/ÆC. Table 1 shows comparatively the physical, thermal and electrical properties of the three types of zirconia. 3.2. OPTICAL PROPERTIES The phenomena that determine the color and shape of a Table 1. Physical properties of zirconia toughened ceramics Property ZTA Mg-PSZ Y-TZP white yellow white Density (gr/cm ) 4.1 5.7 6.0 Average grain size (Ìm) 0.5 50 0.35-0.7 25 2 2 9 10.5 10.5 Maximum temperature ÆC 1000 900 1200 Thermal shock resistance ÆC 250 260 300 Color 3 Thermal conductivity (W/m*K) -6 -1 Coefficient of thermal expansion (*10 K ) (http://www.bce-special-ceramics.com/highperformanceceramics/comparison.php) Hellenic Stomatological Review 57: 101-137, 2013 111 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review ÎÔ‡˜ ·ÈÊÓȉȷÛÌÔ‡˜. ™Â Ù¤ÙÔÈ· ÂÚ›ÙˆÛË ·Ú·ÙËÚÂ›Ù·È ÂÍ¿ÓÙÏËÛË ÙÔ˘ ˘ÙÙÚ›Ô˘ ·fi Ù· fiÚÈ· ÙˆÓ ÎfiÎÎˆÓ Ì ·ÔÙ¤ÏÂÛÌ· ÙË ‰ËÌÈÔ˘ÚÁ›· ΢‚È΋˜ Ê¿Û˘ Ë ÔÔ›· ÂËÚ¿˙ÂÈ ÙË Û˘ÓÔ¯‹ ÙÔ˘ ˘ÏÈÎÔ‡. °È· ÙËÓ ·ÓÙÈÌÂÙÒÈÛË ÙÔ˘ Ê·ÈÓÔ̤ÓÔ˘ ÚÔÙ¿ıËÎÂ Ë ÛÌ›ÎÚ˘ÓÛË ÙˆÓ ÎfiÎÎˆÓ ÛÂ Â›Â‰Ô Ó·ÓÔ̤ÙÚˆÓ ÁÈ· ‚ÂÏÙ›ˆÛË Ù˘ ›‰ÔÛ˘ Î·È Ë ÚÔÛı‹ÎË ¿ÏÏˆÓ ÛÙ·ıÂÚÔÔÈËÙÒÓ. Œ¯ÂÈ ÚÔÙ·ı› Ë ÚÔÛı‹ÎË ‰ËÌËÙÚ›Ô˘ (Ce) Î·È ·ÏÔ˘Ì›Ó·˜ ÁÈ· ÙË ‰ËÌÈÔ˘ÚÁ›· ÂÓfi˜ ¿ÏÏÔ˘ ÛÙ·ıÂÚÔÔÈË̤ÓÔ˘ ÎÂÚ·ÌÈÎÔ‡ Ce-TZP Ì ·ÏÔ˘Ì›Ó·49. H Ï‹Úˆ˜ ÛÙ·ıÂÚÔÔÈË̤ÓË ˙ÈÚÎÔÓ›· Â›Ó·È ÏÈÁfiÙÂÚÔ ÂÏ·ÛÙÈ΋ ·fi ÙË ÌÂÚÈÎÒ˜ ÛÙ·ıÂÚÔÔÈË̤ÓË Î·È ÏÈÁfiÙÂÚÔ ·ÓıÂÎÙÈ΋ ÛÙÔ˘˜ ıÂÚÌÈÎÔ‡˜ ·ÈÊÓȉȷÛÌÔ‡˜ ·fi ÙËÓ MgPSZ. ™Â ıÂÚÌÔÎڷۛ˜ ¿Óˆ ÙˆÓ 900ÆC Â›Ó·È ÂÈÚÚ‹˜ ÛÙËÓ ·Ú·ÌfiÚʈÛË50. ŒÓ·˜ ‚·ÛÈÎfi˜ ÂÚÈÔÚÈÛÌfi˜ ÙˆÓ Y-TZP ÛÙËÓ ¯Ú‹ÛË ÙÔ˘˜ ÛÙËÓ Ô‰ÔÓÙÈ·ÙÚÈ΋ ·ÊÔÚ¿ ÙȘ ÔÙÈΤ˜ ȉÈfiÙËÙ˜ Î·È ÂȉÈο ÙËÓ ·‰È·Ê¿ÓÂÈ· Î·È ÙÔ ¤ÓÙÔÓ· Ï¢Îfi ¯ÚÒÌ· ÙÔ˘˜. °È· ÙÔ ÏfiÁÔ ·˘Ùfi ¤¯Ô˘Ó ‰ÔÎÈÌ·ÛÙ› ‰È¿ÊÔÚ· ÚfiÛıÂÙ· ÔÍÂȉ›ˆÓ ÚÔÎÂÈ̤ÓÔ˘ Ó· ÌÂÙ·‚ÏËı› ÙÔ ¯ÚÒÌ· ÙˆÓ Y-TZP. º·›ÓÂÙ·È ˆ˜ Ë ÚÔÛı‹ÎË Î·È CeO2 Î·È ErO2 ‚ÂÏÙÈÒÓÂÈ ÙË ¯ÚˆÌ·ÙÈ΋ ·fi¯ÚˆÛË ¯ˆÚ›˜ ÛËÌ·ÓÙÈ΋ ›وÛË ÛÙȘ Ì˯·ÓÈΤ˜ ȉÈfiÙËÙ˜51. M¿ÏÈÛÙ· ÙÔ Û‡ÛÙËÌ· Procera AllZirkon (Nobel Biocare, Switzerland) ¤¯ÂÈ ‹‰Ë Ù¤ÛÛÂÚȘ ‰È·ÊÔÚÂÙÈÎÔ‡˜ ¯ÚˆÌ·ÙÈÛÌÔ‡˜. ¶ÚfiÛÊ·Ù· ·Ó·Ù‡ÛÛÔÓÙ·È Û˘ÛÙ‹Ì·Ù· Ó¤·˜ ‰È·Ê·ÓÔ‡˜ ˙ÈÚÎÔÓ›· Ì ̤ÁÂıÔ˜ ÎfiÎÎˆÓ 3 nm Ô˘ ηٷÛ΢¿˙ÂÙ·È Ì ÌÈ· ȉȷ›ÙÂÚË Ù¯ÓÈ΋ Û˘Ì‡ÎÓˆÛ˘ ÈfiÓÙˆÓ ˙ÈÚÎÔÓ›Ô˘, ˘ÙÙÚ›Ô˘ Î·È Ô͢ÁfiÓÔ˘ Û ·¤ÚÈ· Ê¿ÛË Ô˘ ÚÔÔÚ›˙ÂÙ·È ÁÈ· ·ÔηٷÛÙ¿ÛÂȘ ˙ÈÚÎÔÓ›·˜ Ï‹ÚÔ˘˜ ·Ó·ÙÔÌ›·˜ ¯ˆÚ›˜ ÂÈÎ·Ï˘ÙÈÎfi ˘ÏÈÎfi52. 3.1. ºY™IKE™ I¢IOTHTE™ TZP OÈ È‰ÈfiÙËÙ˜ ÙÔ˘ YTZP ÂÍ·ÚÙÒÓÙ·È ·fi ÙÔ ÔÛÔÛÙfi Ù˘ ˘ÙÙÚ›·˜ ηıÒ˜ Î·È ·fi ÙÔ Ì¤ÁÂıÔ˜ ÙˆÓ ÎfiÎΈÓ. H ˘ÎÓfiÙËÙ· Â›Ó·È 6.05-6.07 gr/cm3 Î·È Ë ıÂÚÌÈ΋ ·ÁˆÁÈÌfiÙËÙ· 2.2W/m*K32. H ·ÓÙ›ÛÙ·ÛË ÛÙÔ˘˜ ıÂÚÌÈÎÔ‡˜ ·ÈÊÓȉȷÛÌÔ‡˜ ÏËÛÈ¿˙ÂÈ ÙÔ˘˜ 400ÆC, Î·È Ë ‰ÈËÏÂÎÙÚÈ΋ ÛÙ·ıÂÚ¿ 16-18. Œ¯ÂÈ ÌˉÂÓÈÎfi ÔÚ҉˜, Ï¢Îfi ¯ÚÒÌ· Î·È Ì¤ÁÈÛÙË ıÂÚÌÔÎÚ·Û›· ¯Ú‹Û˘ Ù˘ ÙÔ˘˜ 1500ÆC. TÔ ÛËÌÂ›Ô Ù‹Í˘ Ù˘ Â›Ó·È ÂÍ·ÈÚÂÙÈο ˘„ËÏfi (2750ÆC). O ™˘ÓÙÂÏÂÛÙ‹˜ ıÂÚÌÈ΋˜ ‰È·ÛÙÔÏ‹˜ (™.£.¢.) Â›Ó·È 10,3*10-6/ÆC. ™ÙÔÓ ¶›Ó·Î· 1 Ê·›ÓÔÓÙ·È Û˘ÁÎÚÈÙÈο ÔÈ Ê˘ÛÈΤ˜, ıÂÚÌÈΤ˜ Î·È ËÏÂÎÙÚÈΤ˜ ȉÈfiÙËÙ˜ ÙˆÓ ÙÚÈÒÓ Î·ÙËÁÔÚÈÒÓ ˙ÈÚÎÔÓ›·˜. 3.2. O¶TIKE™ I¢IOTHTE™ T· Ê·ÈÓfiÌÂÓ· Ô˘ ÚÔÛ‰ÈÔÚ›˙Ô˘Ó ¯ÚˆÌ·ÙÈο Î·È Û¯ËÌ·ÙÈο ¤Ó· Ê˘ÛÈÎfi ÛÒÌ· Â›Ó·È Ë ·ÔÚÚfiÊËÛË, Ë ·ÓÙ·Ó¿ÎÏ·ÛË, Ë ‰È¿‰ÔÛË, Ë ‰È¿ıÏ·ÛË Î·È Ë ‰È¿¯˘ÛË4, Ù· ÔÔ›· ηıÔÚ›˙ÔÓÙ·È ‚·ÛÈο ·fi ÙËÓ Â›‰Ú·ÛË ÌÂٷ͇ Ù˘ ÂÈΛÌÂÓ˘ ËÏÂÎÙÚÔÌ·ÁÓËÙÈ΋˜ ·ÎÙÈÓÔ‚ÔÏ›·˜ Î·È ÙˆÓ ËÏÂÎÙÚÔÓ›ˆÓ ÂÓÙfi˜ ÙÔ˘ ˘ÏÈÎÔ‡. H ÂÈΛÌÂÓË ËÏÂÎÙÚÔÌ·ÁÓËÙÈ΋ ·ÎÙÈÓÔ‚ÔÏ›·, Ë ÔÔ›· ¤¯ÂÈ ¤Ó· ÌÂÁ¿ÏÔ Â‡ÚÔ˜ Û˘¯ÓÔÙ‹ÙˆÓ Î·È Ì‹ÎˆÓ Î‡Ì·ÙÔ˜, ÌÔÚ› Ó· ‰ÈÂÁ›ÚÂÈ ¤Ó· ËÏÂÎÙÚfiÓÈÔ Î¿ÓÔÓÙ·˜ ÙÔ Ó· ÌÂÙ·ÎÈÓËı› ·fi ÙÔ ·Ú¯ÈÎfi ÙÔ˘ ÂÓÂÚÁÂÈ·Îfi Â›Â‰Ô Û ¤Ó· ‰È·ÊÔÚÂÙÈÎfi ›‰Ô. K¿ı ˘ÏÈÎfi ·ÓÙȉڿ Ì ‰È·ÊÔÚÂÙÈÎfi ÙÚfiÔ Û οı ̋ÎÔ˜ ·̷ÙÔ˜. O ‚·ıÌfi˜ ·ÔÚÚfiÊËÛ˘ Ù˘ ËÏÂÎÙÚÔÌ·ÁÓËÙÈ΋˜ ·ÎÙÈÓÔ‚ÔÏ›·˜ ÂÍ·ÚÙ¿Ù·È ·fi ÙÔ Â›‰Ô˜ ÙÔ˘ ¯ËÌÈÎÔ‡ ‰ÂÛÌÔ‡ 112 material is the absorption, reflection, transmission, refraction and diffusion3, which are basically determined by the interaction between the electromagnetic radiation and electrons within the material. The external electromagnetic radiation, which has a large range of frequencies and wavelengths, can excite an electron by being moved from its original energy level to a different level. Each material reacts differently to each wavelength. The degree of absorption of electromagnetic radiation depends on the type of chemical bonding and the availability of free electrons. Ceramic materials may entrap some wavelengths of radiation and can be transparent only in a small range. The zirconia ceramics have special optical properties. In the absence of glass due to the high density of the material they present high opacity. Beyond that, depending on the type of material the color can change. They have a high refractive index (2.1-2.2), a low coefficient of absorption and high opacity in the optical and infrared spectrum54. These properties are due to the fact that the dispersed grains (particles) of material are slightly larger than the wavelength of light and the different reflective index of the matrix material. For this reason, in dentistry are used to cover discolorations of the substrate55. Factors affecting the color of the zirconia materials are the grain size, the distribution of grain sizes, the compression method and different additives in each material. The density and homogeneity of the material with minimum porosity (<0.05%) provides a constant opacity of the material. Nevertheless factors affecting the color or transparency of zirconia ceramics were tested without showing that they degrade the mechanical properties55. The Ce-TZP are yellow and in powder form, from yellow to brown. When changing the valence of Ce from +4 to +3 then it turns gray. For this reason it is not used as such for dental use36. Y-TZP ceramics are white, although the products resulting from the production of isostatic compression in the absence of oxygen have originally black color. But when they are subjected to a heat treatment at 1000ÆC-1200ÆC and the presence of oxygen, they gradually acquire white color56. The Mg-PSZ are yellow while the ZTA are white. 3.3. MECHANICAL PROPERTIES There is no doubt that the zirconia ceramics have better mechanical properties than other ceramics such as alumina7. The excellent performance of zirconia ceramics in mechanical testing is primarily due to the dense structure, the microgranules and the absence of defects8. The mechanical properties are affected by the purity of the material, the density, the porosity, the particle size, the crystalline structure (t-c-m phases), the geometrical characteristics and the surface characteristics (Table 2). There is particular interest in the flexural strength which depends on the purity of the material density, the critical particle size, the amount of t- phase and the sintering method. They present flexural strength around 500MPa40, 129, while particularly high values of 900-1200 MPa have been Hellenic Stomatological Review 57: 101-137, 2013 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review ¶›Ó·Î·˜ 1. º˘ÛÈΤ˜ ȉÈfiÙËÙ˜ ÂÓÈÛ¯˘Ì¤ÓˆÓ ÎÂÚ·ÌÈÎÒÓ Ì ˙ÈÚÎÔÓ›· I‰ÈfiÙËÙ· ZTA Mg-PSZ Y-TZP Ï¢Îfi K›ÙÚÈÓÔ §Â˘Îfi ¶˘ÎÓfiÙËÙ· (gr/cm ) 4.1 5.7 6.0 M¤ÛÔ Ì¤ÁÂıÔ˜ ÎfiÎÎÔ˘ (Ìm) 0.5 50 0.35-0.7 £ÂÚÌÈ΋ ·ÁˆÁÈÌfiÙËÙ· (W/m*K) 25 2 2 9 10.5 10.5 M¤ÁÈÛÙË ıÂÚÌÔÎÚ·Û›· ÆC 1000 900 1200 AÓÙ›ÛÙ·ÛË ÛÙ· ıÂÚÌÈο ÛÙÚ˜ÆC 250 260 300 XÚÒÌ· 3 -6 -1 ™£¢ (*10 K ) (http://www.bce-special-ceramics.com/highperformanceceramics/comparison.php) Table 2. Mechanical properties of zirconia Property/Material Y-TZP Ce-TZP ZTA Mg-PSZ Density (gr/cm ) 6.05 6.15 4.15 5.75 Hardness (HV30) 1350 900 1600 1020 Bending strength (MPa) 1000 350 500 800 Compression strength (MPa) 2000 - - 2000 Modulus of elasticity (GPa) 205 215 380 205 3 Î·È ÙËÓ ‰È·ıÂÛÈÌfiÙËÙ· ÂχıÂÚˆÓ ËÏÂÎÙÚÔÓ›ˆÓ. T· ÎÂÚ·ÌÈο ˘ÏÈο ÌÔÚÔ‡Ó Ó· ÂÁÎψ‚›˙Ô˘Ó ÔÚÈṲ̂ӷ Ì‹ÎË Î‡Ì·ÙÔ˜ Ù˘ ·ÎÙÈÓÔ‚ÔÏ›·˜ Î·È Ó· Â›Ó·È ‰È·Ê·Ó‹ ÌfiÓÔ Û ¤Ó· ÌÈÎÚfi ‡ÚÔ˜ ·˘ÙÒÓ55. T· ÎÂÚ·ÌÈο Ù˘ ˙ÈÚÎÔÓ›·˜ ¤¯Ô˘Ó ȉȷ›ÙÂÚ˜ ÔÙÈΤ˜ ȉÈfiÙËÙ˜. §fiÁˆ Ù˘ ·Ô˘Û›·˜ Á˘·ÏÈÔ‡ Î·È ÂÍ·ÈÙ›·˜ Ù˘ ÌÂÁ¿Ï˘ ˘ÎÓfiÙËÙ·˜ ÙÔ˘ ˘ÏÈÎÔ‡ ·ÚÔ˘ÛÈ¿˙Ô˘Ó ¤ÓÙÔÓË ·‰È·Ê¿ÓÂÈ·. Afi ÂΛ Î·È ¤Ú· ·Ó¿ÏÔÁ· Ì ÙÔÓ Ù‡Ô ÙÔ˘ ˘ÏÈÎÔ‡ ÙÔ ¯ÚÒÌ· ÌÂÙ·‚¿ÏÏÂÙ·È. Œ¯Ô˘Ó ˘„ËÏfi ‰Â›ÎÙË ·Ó¿ÎÏ·Û˘ (2.1-2.2), ¯·ÌËÏfi Û˘ÓÙÂÏÂÛÙ‹ ·ÔÚÚfiÊËÛ˘ Î·È ˘„ËÏ‹ ·‰È·Ê¿ÓÂÈ· ÛÙÔ ÔÙÈÎfi Î·È ˘¤Ú˘ıÚÔ Ê¿ÛÌ·54. OÈ È‰ÈfiÙËÙ˜ ·˘Ù¤˜ ÔÊ›ÏÔÓÙ·È ÛÙÔ ÁÂÁÔÓfi˜ fiÙÈ ÔÈ ‰ÈÂÛ·Ṳ́ÓÔÈ ÎfiÎÎÔÈ (particles) ÙÔ˘ ˘ÏÈÎÔ‡ Â›Ó·È ÂÏ¿¯ÈÛÙ· ÌÂÁ·Ï‡ÙÂÚÔÈ ·fi ÙÔ Ì‹ÎÔ˜ ·̷ÙÔ˜ ÙÔ˘ ʈÙfi˜ Î·È ÛÙÔ ‰È·ÊÔÚÂÙÈÎfi ‰Â›ÎÙ˘ ·Ó¿ÎÏ·Û˘ Ù˘ Ì‹ÙÚ·˜ ÙÔ˘ ˘ÏÈÎÔ‡. °È· ÙÔ ÏfiÁÔ ·˘Ùfi ÛÙËÓ Ô‰ÔÓÙÈ·ÙÚÈ΋ ¯ÚËÛÈÌÔÔÈÂ›Ù·È ÁÈ· Ó· ηχ„ÂÈ ‰˘Û¯ÚˆÌ›Â˜ ÙÔ˘ ˘ÔÛÙÚÒÌ·ÙÔ˜55. ¶·Ú¿ÁÔÓÙ˜ Ô˘ ÂËÚ¿˙Ô˘Ó ÙÔ ¯ÚÒÌ· ÙˆÓ ˘ÏÈÎÒÓ Ù˘ ˙ÈÚÎÔÓ›·˜ Â›Ó·È ÙÔ Ì¤ÁÂıÔ˜ ÙÔ˘ ÎfiÎÎÔ˘, Ë Î·Ù·ÓÔÌ‹ ÙˆÓ ÌÂÁÂıÒÓ ÙˆÓ ÎfiÎΈÓ, Ë Ì¤ıÔ‰Ô˜ Û˘Ì›ÂÛ˘ Î·È Ù· ‰È·ÊÔÚÂÙÈο ÚfiÛıÂÙ· οı ˘ÏÈÎÔ‡. H ˘ÎÓfiÙËÙ· Î·È ÔÌÔÈÔÁ¤ÓÂÈ· ÙÔ˘ ˘ÏÈÎÔ‡ Ì ÂÏ¿¯ÈÛÙÔ ÔÚ҉˜ (<0,05%) ·Ú¤¯ÂÈ ÌÈ· ÛÙ·ıÂÚ‹ ·‰È·Ê¿ÓÂÈ· ÛÙÔ ˘ÏÈÎfi. ¶·ÚfiÏ· ·˘Ù¿ ¤¯Ô˘Ó ‰ÔÎÈÌ·ÛÙ› Î·È ·Ú¿ÁÔÓÙ˜ Ô˘ ÂËÚ¿˙Ô˘Ó ÙÔ ¯ÚÒÌ· ‹ ÙË ‰È·Ê¿ÓÂÈ· Ù˘ ˙ÈÚÎÔÓ›·˜ ¯ˆÚ›˜ Ó· Hellenic Stomatological Review 57: 101-137, 2013 recorded for the Y-TZP7 ceramics. The value of 900 MPa results from technical sintering without pressure and the value of 1200 MPa is achieved by fusing at high pressure (HiP)40. The performance of ZTA ceramics in bending tests gives smaller values of 400-450 MPa39. Young’s modulus is relatively low, allowing large deformation of the material up to failure, a unique property in brittle materials. This allows a significant absorption of stresses that responds excellent during fatigue tests7. In the literature there is a wide range of zirconia fracture toughness values that vary from 4-19 MPa m-1/2. Comparison of these values is difficult as they result from different techniques and are influenced by the particle size, density and percentage of impurities of each particular ceramic57. However, the Y TZP fracture toughness is higher than other ceramics such as alumina. 3.4. APPLICATIONS IN INDUSTRY - OTHER APPLICATIONS Zirconia is primarily used in industry. A particularly important application of cubic zirconia YSZ (Y-16 %) is in fuel cells. Zirconia is used as an electrolyte with very thin coating thickness, which is responsible for the low resistance to electrical leakage and lower operating temperature of the cell58. However, as mentioned above, the cubic 113 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review Ê·›ÓÂÙ·È fiÙÈ ˘Ô‚·ıÌ›˙Ô˘Ó ÙȘ Ì˯·ÓÈΤ˜ ȉÈfiÙËÙ˜55. T· ÎÂÚ·ÌÈο Ce-TZP Â›Ó·È Î›ÙÚÈÓ· Î·È Û ÌÔÚÊ‹ ÛÎfiÓ˘ ·fi ΛÙÚÈÓÔ ¤ˆ˜ ηʤ. M¿ÏÈÛÙ· fiÙ·Ó ÌÂÙ·‚¿ÏÏÂÈ Ûı¤ÓÔ˜ ÙÔ Ce ·fi +4 Û +3 ÙfiÙ Á›ÓÂÙ·È ÁÎÚÈ. °È· ÙÔ ÏfiÁÔ ·˘Ùfi ‰Â ¯ÚËÛÈÌÔÔÈÔ‡ÓÙ·È ·˘ÙÔ‡ÛÈ· ÁÈ· Ô‰ÔÓÙÈ·ÙÚÈ΋ ¯Ú‹ÛË36. T· ÎÂÚ·ÌÈο Y-TZP Â›Ó·È ÏÂ˘Î¿, ·Ó Î·È Ù· ÚÔ˚fiÓÙ· Ô˘ ÚÔ·ÙÔ˘Ó ·fi ·Ú·ÁˆÁ‹ ÈÛÔÛÙ·ÙÈ΋˜ Û˘Ì›ÂÛ˘ Û ·Ô˘Û›· Ô͢ÁfiÓÔ˘ ¤¯Ô˘Ó ·Ú¯Èο Ì·‡ÚÔ ¯ÚÒÌ·. EÓ Û˘Ó¯›· fï˜ ˘fiÎÂÈÓÙ·È Û ıÂÚÌÈ΋ ÂÂÍÂÚÁ·Û›· ÛÙÔ˘˜ 1000ÆC-1200ÆC Î·È ·ÚÔ˘Û›· Ô͢ÁfiÓÔ˘, ·ÔÎÙÒÓÙ·˜ ÛÙ·‰È·Î¿ ¤Ó· ¿ÛÚÔ ¯ÚÒÌ·56. T· ÎÂÚ·ÌÈο Mg-PSZ Â›Ó·È Î›ÙÚÈÓÔ˘ ¯ÚÒÌ·ÙÔ˜ ÂÓÒ Ù· ZTA Â›Ó·È ÏÂ˘Î¿. 3.3. MHXANIKE™ I¢IOTHTE™ ¢ÂÓ ˘¿Ú¯ÂÈ Î·Ì›· ·ÌÊÈ‚ÔÏ›· fiÙÈ Ù· ÎÂÚ·ÌÈο ˙ÈÚÎÔÓ›·˜ ¤¯Ô˘Ó ηχÙÂÚ˜ Ì˯·ÓÈΤ˜ ȉÈfiÙËÙ˜ ·fi ¿ÏÏ· ÎÂÚ·ÌÈο fiˆ˜ ÁÈ· ·Ú¿‰ÂÈÁÌ· Ë ·ÏÔ˘Ì›Ó·7. H ÂÍ·ÈÚÂÙÈ΋ ·fi‰ÔÛË ÙˆÓ ÎÂÚ·ÌÈÎÒÓ ˙ÈÚÎÔÓ›·˜ ÛÙȘ Ì˯·ÓÈΤ˜ ‰ÔÎÈ̤˜ ÔÊ›ÏÂÙ·È ÚÒÙÈÛÙ· ÛÙËÓ ˘ÎÓ‹ ‰ÔÌ‹, ÛÙÔ˘˜ ÌÈÎÚÔÎfiÎÎÔ˘˜ Î·È ÛÙËÓ ·Ô˘Û›· ·ÙÂÏÂÈÒÓ8. OÈ Ì˯·ÓÈΤ˜ ȉÈfiÙËÙ˜ ÂËÚ¿˙ÔÓÙ·È ·fi ÙË Î·ı·ÚfiÙËÙ· ÙÔ˘ ˘ÏÈÎÔ‡, ÙËÓ ˘ÎÓfiÙËÙ·, ÙÔ ÔÚ҉˜, ÙÔ Ì¤ÁÂıÔ˜ ÙˆÓ ÎfiÎΈÓ, ·fi ÙËÓ ÎÚ˘ÛÙ·ÏÏÈ΋ ‰ÔÌ‹ (t-c-m Ê¿ÛÂȘ), ·fi Ù· ÁˆÌÂÙÚÈο ¯·Ú·ÎÙËÚÈÛÙÈο Î·È Ù· ÂÈÊ·ÓÂȷο ¯·Ú·ÎÙËÚÈÛÙÈο (¶›Ó·Î·˜ 2). I‰È·›ÙÂÚ· Ì·˜ ÂӉȷʤÚÂÈ Ë ·ÓÙÔ¯‹ ÛÂ Î¿Ì„Ë Ë ÔÔ›· ÂÍ·ÚÙ¿Ù·È ·fi ÙËÓ Î·ı·ÚfiÙËÙ·, ˘ÎÓfiÙËÙ· ÙÔ˘ ˘ÏÈÎÔ‡, ÙÔ ÎÚ›ÛÈÌÔ Ì¤ÁÂıÔ˜ ÙˆÓ ÎfiÎΈÓ, ÙÔ ÔÛfi Ù˘ t-Ê¿Û˘ Î·È ÙË Ì¤ıÔ‰Ô ˘ÚÔÛ˘Ûۈ̿وÛ˘8. H ·ÓÙÔ¯‹ ÛÙËÓ Î¿Ì„Ë ÙˆÓ ÎÂÚ·ÌÈÎÒÓ Y-TZP Î˘Ì·›ÓÂÙ·È Á‡Úˆ ÛÙ· 500MPa40, 128, ÂÓÒ ¤¯Ô˘Ó ηٷÁÚ·Ê› Î·È È‰È·›ÙÂÚ· ˘„ËϤ˜ ÙÈ̤˜ Ù˘ Ù¿Í˘ ÙˆÓ 900-1200 MPa7. H ÙÈÌ‹ ÙˆÓ 900 MPa ÚÔ·ÙÂÈ ·fi ÙËÓ Ù¯ÓÈ΋ ˘ÚÔÛ˘Ûۈ̿وÛ˘ ¯ˆÚ›˜ ›ÂÛË Î·È Ë ÙÈÌ‹ ÙˆÓ 1200 MPa ÂÈÙ˘Á¯¿ÓÂÙ·È Î·Ù¿ ÙËÓ Û‡ÓÙËÍË Û ˘„ËÏ‹ ›ÂÛË (HiP)40, 57. H ›‰ÔÛË ÙˆÓ ZTA ÛÙȘ ‰ÔÎÈ̤˜ ο̄˘ ‰›ÓÂÈ ÌÈÎÚfiÙÂÚ˜ ÙÈ̤˜ 400-450 MPa39. TÔ Ì¤ÙÚÔ ÂÏ·ÛÙÈÎfiÙËÙ·˜ Â›Ó·È Û¯ÂÙÈο ¯·ÌËÏfi ÂÈÙÚ¤ÔÓÙ·˜ ÌÂÁ¿ÏË ·Ú·ÌfiÚʈÛË ÙÔ˘ ˘ÏÈÎÔ‡ ̤¯ÚÈ ÙË ıÚ·‡ÛË ÙÔ˘, ÌÔÓ·‰È΋ ȉÈfiÙËÙ· ÛÙ· „·ı˘Ú¿ ˘ÏÈο. A˘Ùfi ÂÈÙÚ¤ÂÈ ÌÈ· ÛËÌ·ÓÙÈ΋ ·ÔÚÚfiÊËÛË Ù¿ÛÂˆÓ Ô˘ ·ÓÙ·ÔÎÚ›ÓÂÙ·È ¿ÚÈÛÙ· ÛÙȘ ‰ÔÎÈ̤˜ ÎfiˆÛ˘8. ™ÙË ‚È‚ÏÈÔÁÚ·Ê›· ˘¿Ú¯ÂÈ ¤Ó· ÌÂÁ¿ÏÔ Â‡ÚÔ˜ ÙÈÌÒÓ ‰˘ÛıÚ·˘ÛÙfiÙËÙ·˜ ÁÈ· ÙË ˙ÈÚÎÔÓ›· Î·È ÔÈΛÏÂÈ ·fi 4-19MPa m-1/2. H Û‡ÁÎÚÈÛË ·˘ÙÒÓ ÙˆÓ ÙÈÌÒÓ Â›Ó·È ‰‡ÛÎÔÏË Î·ıÒ˜ ÚÔ·ÙÔ˘Ó ·fi ‰È·ÊÔÚÂÙÈΤ˜ Ù¯ÓÈΤ˜ Î·È ÂËÚ¿˙ÔÓÙ·È ·fi ÙÔ Ì¤ÁÂıÔ˜ zirconia has low toughness which can lead to cracking in long term use. For this reason more recently it has been proposed to add alumina in cubic zirconia electrolytes to improve the hardness and fracture toughness (Kic) but in a small proportion, as the addition of alumina has a negative impact on the electrical conductivity59. Another application of zirconia is in high performance or pressure chromatography (HPLC). Due to the high pressure, the HPLC is rapid (results in some minutes) and due to fine grain adsorbents materials that are used provide high separation efficiency. The main reason is the excellent chemical and thermal stability, which remains even at temperatures above 300ÆC for a long time60. Silica (SiO2) was the first of the materials used as gate dielectric materials for the manufacture of integrated circuits. But as it was necessary to gradually reduce the size of the devices, the size of the membranes had to respectively decrease and in order to create current leakage the use of materials with higher dielectric constant was proposed. Partially stabilized zirconia (YSZ) is one of the materials that can remain thermodynamically stable in contact with silicon even at 1000ÆC and therefore is quite promising as gate dielectric material to replace SiO261. Cubic zirconia is used in oxygen sensors which have a wide range of industrial applications. Such sensors are used to control the oxygen content in exhaust gases or molten metals. In automotive industry is known as oxygen sensors (Ï)-type62. Combining the high durability and the improved conductivity compared to that of fully stabilized zirconia ceramics, Y-TZP ceramics are excellent for use as electrolytes in electrochemical applications such reactors, oxygen pumps and fuel cells63. The chemical stability, high melting point, electrical and optical properties makes them ideal components for high resistance to wear and for connecting optical fibers64. There is a wide variety of applications of zirconia in its various forms, which are summarized in Table 39. ZIRCONIA CERAMICS IN DENTISTRY Although there are many types of systems in the industry of ceramics containing zirconia65, three are currently available for use in dentistry. These are fully stabilized tetragonal zirconia, partially stabilized zirconia and zirconia -reinforced alumina. ¶›Ó·Î·˜ 2. ªË¯·ÓÈΤ˜ ȉÈfiÙËÙ˜ ˙ÈÚÎÔÓ›·˜ I‰ÈfiÙËÙ·/YÏÈÎfi Y-TZP Ce-TZP ZTA Mg-PSZ 3 ¶˘ÎÓfiÙËÙ· (gr/cm ) 6.05 6.15 4.15 5.75 ™ÎÏËÚfiÙËÙ· (HV30) 1350 900 1600 1020 AÓÙÔ¯‹ ÛÙËÓ Î¿Ì„Ë (MPa) 1000 350 500 800 AÓÙÔ¯‹ ÛÙË Û˘Ì›ÂÛË (MPa) 2000 - - 2000 M¤ÙÚÔ ÂÏ·ÛÙÈÎfiÙËÙ·˜ (GPa) 205 215 380 205 114 Hellenic Stomatological Review 57: 101-137, 2013 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review Table 3. Major Zirconia industrial applications Valve and pump parts Cable guides Cutting tools Friction and dispersal means Oxygen Sensors Fuel cells membranes Thermal Barriers Fiber optic accessories ÎfiÎΈÓ, ˘ÎÓfiÙËÙ· Î·È ÔÛÔÛÙfi ÚÔƯ͈̂Ó57. ¶¿ÓÙˆ˜ Ë ‰˘ıÚ·˘ÛÙfiÙËÙ· ÙˆÓ ÎÂÚ·ÌÈÎÒÓ Y-TZP Â›Ó·È ˘„ËÏfiÙÂÚË Û ۯ¤ÛË Ì ¿ÏÏ· ÎÂÚ·ÌÈο fiˆ˜ Ë ·ÏÔ˘Ì›Ó·. 3.4. EºAPMO°E™ ™TH BIOMHXANIA - A§§E™ EºAPMO°E™ H ˙ÈÚÎÔÓ›· ¯ÚËÛÈÌÔÔÈÂ›Ù·È ÛÙȘ ÂÚÈÛÛfiÙÂÚ˜ ÌÔÚʤ˜ Ù˘ ÛÙË ‚ÈÔÌ˯·Ó›·. MÈ· ȉȷ›ÙÂÚ· ÛËÌ·ÓÙÈ΋ ÂÊ·ÚÌÔÁ‹ Ù˘ ΢‚È΋˜ ˙ÈÚÎÔÓ›·˜ YSZ (Y-16%) Â›Ó·È ÛÙȘ ΢„¤Ï˜ η˘Û›ÌÔ˘. H ˙ÈÚÎÔÓ›· ¯ÚËÛÈÌÔÔÈÂ›Ù·È ˆ˜ ËÏÂÎÙÚÔχÙ˘ Î·È Ì¿ÏÈÛÙ· Ì ȉȷ›ÙÂÚ· ÏÂÙfi ¿¯Ô˜ ›ÛÙÚˆÛ˘ ÂÈÙ˘Á¯¿ÓÂÙ·È ¯·ÌËÏ‹ ·ÓÙ›ÛÙ·ÛË, ËÏÂÎÙÚÈ΋ ‰È·ÚÚÔ‹ Î·È ¯·ÌËÏfiÙÂÚË ıÂÚÌÔÎÚ·Û›· ÏÂÈÙÔ˘ÚÁ›·˜ Ù˘ ΢„¤Ï˘58. ŸÌˆ˜, fiˆ˜ ÚԷӷʤÚıËÎÂ, Ë Î˘‚È΋ ˙ÈÚÎÔÓ›· ¤¯ÂÈ ¯·ÌËÏ‹ ‰˘ÛıÚ·˘ÛÙfiÙËÙ· Ú¿ÁÌ· Ô˘ ÌÔÚ› Ó· Ô‰ËÁ‹ÛÂÈ Û ‰ËÌÈÔ˘ÚÁ›· ÚˆÁÌÒÓ Û ̷ÎÚfi¯ÚÔÓË ÏÂÈÙÔ˘ÚÁ›·. °È· ÙÔ ÏfiÁÔ ·˘Ùfi ÚfiÛÊ·Ù· ÚÔÙ¿ıËÎÂ Ë ÚÔÛı‹ÎË ·ÏÔ˘Ì›Ó·˜ Û ËÏÂÎÙÚÔχÙ˜ ΢‚È΋˜ ˙ÈÚÎÔÓ›·˜ ÒÛÙ ӷ ‚ÂÏÙȈı› Ë ÛÎÏËÚfiÙËÙ· Î·È Ë ‰˘ıÚ·˘ÛÙfiÙËÙ· Kic ·ÏÏ¿ Û ÌÈÎÚfi ÔÛÔÛÙfi ηıÒ˜ Ë ÚÔÛı‹ÎË ·ÏÔ˘Ì›Ó·˜ ¤¯ÂÈ ·ÚÓËÙÈ΋ ›وÛË ÛÙËÓ ËÏÂÎÙÚÈ΋ ·ÁˆÁÈÌfiÙËÙ·59. MÈ· ¿ÏÏË ÂÊ·ÚÌÔÁ‹ ÙˆÓ ÎÂÚ·ÌÈÎÒÓ ˙ÈÚÎÔÓ›·˜ Â›Ó·È ÛÙË ¯ÚˆÌ·ÙÔÁÚ·Ê›· ˘„ËÏ‹˜ ·fi‰ÔÛ˘ ‹ ›ÂÛ˘ (HPLC). §fiÁˆ Ù˘ ˘„ËÏ‹˜ ȤÛˆ˜, Ë HPLC Â›Ó·È Ù·¯‡Ù·ÙË (·Ú¤¯ÂÈ ·ÔÙ¤ÏÂÛÌ· Û ÌÂÚÈο ÏÂÙ¿ Ù˘ ÒÚ·˜) Î·È ÂÂȉ‹ ¯ÚËÛÈÌÔÔÈÔ‡ÓÙ·È ÏÂÙfiÎÔÎη ˘ÏÈο ÚÔÛÚfiÊËÛ˘ (Ï›Á· Ìm) ·Ú¤¯ÂÈ ÌÂÁ¿ÏË ÈηÓfiÙËÙ· ‰È·¯ˆÚÈÛÌÔ‡. O ·ÚÈÔ˜ ÏfiÁÔ˜ Â›Ó·È Ë ÂÍ·ÈÚÂÙÈ΋ ¯ËÌÈ΋ Î·È ıÂÚÌÈ΋ ÛÙ·ıÂÚfiÙËÙ· Ù˘, Ë ÔÔ›· ·Ú·Ì¤ÓÂÈ ·ÎfiÌ· Î·È Û ıÂÚÌÔÎڷۛ˜ ¿Óˆ ÙˆÓ 300ÆC ÁÈ· ÌÂÁ¿ÏÔ ¯ÚÔÓÈÎfi ‰È¿ÛÙËÌ·60. To ‰ÈÔÍ›‰ÈÔ ˘ÚÈÙ›Ô˘ (SiO2) ˘‹ÚÍ ·fi Ù· ÚÒÙ· ˘ÏÈο Ô˘ ¯ÚËÛÈÌÔÔÈ‹ıËÎ·Ó ˆ˜ ‰ÈËÏÂÎÙÚÈο ˘ÏÈο ‡Ï˘ ÁÈ· ÙËÓ Î·Ù·Û΢‹ ÔÏÔÎÏËÚˆÌ¤ÓˆÓ Î˘Îψ̿وÓ. K·ıÒ˜ fï˜ ¯ÚÂÈ¿ÛÙËΠӷ ÌÂȈı› ÛÙ·‰È·Î¿ ÙÔ Ì¤ÁÂıÔ˜ ÙˆÓ Û˘Û΢ÒÓ, ÌÂÈÒıËΠ·ÓÙ›ÛÙÔȯ· ÙÔ Ì¤ÁÂıÔ˜ ÙˆÓ ÌÂÌ‚Ú·ÓÒÓ Î·È ÚÔÎÂÈ̤ÓÔ˘ Ó· ‰ËÌÈÔ˘ÚÁËı› ‰È·ÚÚÔ‹ Ú‡̷ÙÔ˜ ÚÔÙ¿ıËÎÂ Ë ¯Ú‹ÛË ˘ÏÈÎÒÓ Ì ÌÂÁ·Ï‡ÙÂÚË ‰ÈËÏÂÎÙÚÈ΋ ÛÙ·ıÂÚ¿. H ÌÂÚÈÎÒ˜ ÛÙ·ıÂÚÔÔÈË̤ÓË ˙ÈÚÎÔÓ›· (YSZ) Â›Ó·È ¤Ó· ·fi Ù· ˘ÏÈο Ô˘ ÌÔÚÔ‡Ó Ó· ·Ú·Ì¤ÓÔ˘Ó ıÂÚÌÔ‰˘Ó·ÌÈο ÛÙ·ıÂÚ¿ Û ·ʋ Ì ˘Ú›ÙÈÔ ·ÎfiÌ· Î·È Û 1000ÆC, Î·È Û˘ÓÂÒ˜ ·ÚÎÂÙ¿ ˘ÔÛ¯fiÌÂÓÔ ‰ÈËÏÂÎÙÚÈÎfi ˘ÏÈÎfi ‡Ï˘ ÁÈ· Ó· ·ÓÙÈηٷÛÙ‹ÛÂÈ ÙÔ SiO261. H ΢‚È΋ ˙ÈÚÎÔÓ›· ¯ÚËÛÈÌÔÔÈÂ›Ù·È Û ·ÈÛıËÙ‹Ú˜ Ô͢ÁfiÓÔ˘ ÔÈ ÔÔ›ÔÈ ¤¯Ô˘Ó ¤Ó· ÌÂÁ¿ÏÔ Ê¿ÛÌ· ‚ÈÔÌ˯·ÓÈÎÒÓ ÂÊ·ÚÌÔÁÒÓ. T¤ÙÔÈÔÈ ·ÈÛıËÙ‹Ú˜ ¯ÚËÛÈÌÔÔÈÔ‡ÓÙ·È ÁÈ· ÙÔÓ ¤ÏÂÁ¯Ô ÂÚÈÂÎÙÈÎfiÙËÙ·˜ Ô͢ÁfiÓÔ˘ Û η˘Û·¤ÚÈ· ‹ Hellenic Stomatological Review 57: 101-137, 2013 Most manufactured zirconia ceramics for dental clinical use are those of partially stabilized tetragonal zirconia, which, depending on the laboratory manufacturing process are divided into two categories. The first one, where milling and machining is performed during the socalled «green stage», the partially sintered form. In this category, high performance systems are: CEREC 3 and in lab DCS Precident, Procera, Lava, Cercon Smart Ceramics, Everest, Denzir, DentaCad and Evolution D4D. As a disadvantage is considered the fact that the frameworks must be done larger by 20-25% in order to counteract the contraction that occurs during the final stage of sintering. Unlike, the cutting and milling in this form of zirconia is faster and cutting tools that serve this purpose suffer less wear66. In the second category the milling and construction are completed in the fully sintered format after burning down and compression (Hot Isostatic Pressing or HiP) of zirconia. The main representatives of this technique are the systems DC-Zirkon (DCS Dental AG), Everest-ZH (Kavo), Denzir (Cadesthetics AB)67, 23. This technique is advantageous in that the final versions of the frameworks do not undergo dimensional changes. On the other hand cutting and processing is extremely difficult and time consuming because of the high hardness of the material66. Even today there is no consensus among researchers regarding the choice of method of manufacturing zirconia frameworks concerning which is less damaging to the final product, and that is the reason that both the aforementioned techniques still exist68. Table 4 contains the major CAD-CAM system for zirconia materials processing. ZIRCONIA CERAMICS APPLICATIONS IN DENTISTRY Dental prosthetic restorations should serve the function and patient comfort and maintain their integrity over time70. The selection of appropriate materials therefore must be driven by the success and survival of restorations. Zirconia ceramics are used in a wide range of applications in dentistry. Therefore together with metal-ceramic and other systems add an alternative approach in reconstructions where strength has to be combined with increased demands for aesthetics. SINGLE TOOTH RESTORATIONS The most frequently used individual dental restorations in 115 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review Û ÙËÁ̤ӷ ̤ٷÏÏ·. ™ÙËÓ ·˘ÙÔÎÈÓËÙÔ‚ÈÔÌ˯·Ó›· ÂÊ·ÚÌÔÁ‹ Â›Ó·È ÁÓˆÛÙÔ› ˆ˜ ·ÈÛıËÙ‹Ú˜ Ͽ̉· (Ï)62. ™˘Ó‰˘¿˙ÔÓÙ·˜ ÙËÓ ˘„ËÏ‹ ·ÓÙÔ¯‹ Î·È ÙËÓ ‚ÂÏÙȈ̤ÓË ·ÁˆÁÈÌfiÙËÙ· ·fi ÂΛÓË Ù˘ Ï‹Úˆ˜ ÛÙ·ıÂÚÔÔÈË̤Ó˘ ˙ÈÚÎÔÓ›·˜ Ù· ÎÂÚ·ÌÈο Y-TZP Â›Ó·È ÂÍ·ÈÚÂÙÈο ÁÈ· ¯Ú‹ÛË Û·Ó ËÏÂÎÙÚÔχÙ˜ Û ÂÊ·ÚÌÔÁ¤˜ fiˆ˜ ËÏÂÎÙÚÔ¯ËÌÈÎÔ› ·ÓÙȉڷÛÙ‹Ú˜, ·ÓÙϛ˜ Ô͢ÁfiÓÔ˘ Î·È Î˘„¤Ï˜ η˘Û›ÌÔ˘64. H ¯ËÌÈ΋ ÛÙ·ıÂÚfiÙËÙ·, ÙÔ ˘„ËÏfi ÛËÌÂ›Ô Ù‹Í˘, ÔÈ ËÏÂÎÙÚÈΤ˜ Î·È ÔÙÈΤ˜ ȉÈfiÙËÙ¤˜ ÙÔ˘˜ Ù· ηıÈÛÙ¿ ȉ·ÓÈο ÁÈ· ÂÍ·ÚÙ‹Ì·Ù· ˘„ËÏ‹˜ ·ÓÙ›ÛÙ·Û˘ ÛÙËÓ ÊıÔÚ¿ Î·È ÁÈ· Û‡Ó‰ÂÛË ÔÙÈÎÒÓ ÈÓÒÓ. Y¿Ú¯ÂÈ Ì›· ÌÂÁ¿ÏË ÔÈÎÈÏ›· ÂÊ·ÚÌÔÁÒÓ Ù˘ ˙ÈÚÎÔÓ›·˜ Û ‰È¿ÊÔÚ˜ ÌÔÚʤ˜ Ù˘, ÔÈ Ôԛ˜ Û˘ÓÔ„›˙ÔÓÙ·È ÛÙÔÓ ¶›Ó·Î· 39. Table 4A. Current zirconia “green stage” CAD-CAM systems System Material synthesis Cercon PSZ DC-Zirkon PSZ IPS e.max ZirCAD PSZ LAVA Frame PSZ ProceraAllCeram alumina KEPAMIKA ZIPKONIA™ ™THN O¢ONTIATPIKH ProceraAllZirkon PSZ ¶·Ú¿ ÙÔ ÁÂÁÔÓfi˜ fiÙÈ ˘¿Ú¯Ô˘Ó ÔÏÏÔ› Ù‡ÔÈ ÎÂÚ·ÌÈÎÒÓ ÂÊ·ÚÌÔÁÒÓ ÛÙË ‚ÈÔÌ˯·Ó›· Ô˘ ÂÚȤ¯Ô˘Ó ˙ÈÚÎÔÓ›·65, ÙÚÂȘ Â›Ó·È Û‹ÌÂÚ· ‰È·ı¤ÛÈÌÔÈ ÁÈ· ¯Ú‹ÛË ÛÙËÓ O‰ÔÓÙÈ·ÙÚÈ΋. A˘ÙÔ› Â›Ó·È Ë Ï‹Úˆ˜ ÛÙ·ıÂÚÔÔÈË̤ÓË ÙÂÙÚ·ÁˆÓÈ΋ ˙ÈÚÎÔÓ›·, Ë ÌÂÚÈÎÒ˜ ÛÙ·ıÂÚÔÔÈË̤ÓË ˙ÈÚÎÔÓ›· Î·È Ë ·ÏÔ˘Ì›Ó· ÂÓÈÛ¯˘Ì¤ÓË Ì ˙ÈÚÎÔÓ›·. T· ÂÚÈÛÛfiÙÂÚ· ηٷÛ΢·˙fiÌÂÓ· ÎÂÚ·ÌÈο ˙ÈÚÎÔÓ›·˜ Û ÎÏÈÓÈ΋ ¯Ú‹ÛË Â›Ó·È ·˘Ù¿ Ù˘ Ï‹Úˆ˜ ÛÙ·ıÂÚÔÔÈË̤Ó˘ ÙÂÙÚ·ÁˆÓÈ΋˜ ˙ÈÚÎÔÓ›·˜, Ù· ÔÔ›· ·Ó¿ÏÔÁ· Ì ÙËÓ ÂÚÁ·ÛÙËÚȷ΋ ‰È·‰Èηۛ· ηٷÛ΢‹˜ ÙÔ˘˜ ‰È·ÎÚ›ÓÔÓÙ·È Û ‰‡Ô ηÙËÁÔڛ˜. H ÚÒÙË ÂÎÙÂÏ› ÙÔÓ ÂÎÙÚÔ¯ÈÛÌfi Ù˘ ÚÒÙ˘ ‡Ï˘ ηٿ ÙÔ ÏÂÁfiÌÂÓÔ «green stage», ‰ËÏ·‰‹ ÛÙË ÌÂÚÈÎÒ˜ Û˘ÓÙËÁ̤ÓË ÌÔÚÊ‹ Ù˘. ™Â ·˘Ù‹ ÙË Î·ÙËÁÔÚ›· ÂÚÈÏ·Ì‚¿ÓÔÓÙ·È ÔÈΛϷ ·ÍÈfiÏÔÁ· Û˘ÛÙ‹Ì·Ù· ˘„ËÏ‹˜ ·fi‰ÔÛ˘: CEREC 3 Î·È in lab DCS Precident, Procera, Lava, Cercon Smart Ceramics, Everest, Denzir, DentaCad Î·È Evolution D4D. MÂÈÔÓ¤ÎÙËÌ· ıˆÚÂ›Ù·È ÙÔ ÁÂÁÔÓfi˜ fiÙÈ ÔÈ ÛÎÂÏÂÙÔ› Ô˘ ηٷÛ΢¿˙ÔÓÙ·È Ì ·˘Ù‹Ó ÙËÓ Ù¯ÓÈ΋ Â›Ó·È ÌÂÁÂı˘Ì¤ÓÔÈ Î·Ù¿ 20-25% ÁÈ· Ó· ·ÓÙÈÚÚÔ‹ÛÔ˘Ó ÙË Û˘ÛÙÔÏ‹ Ô˘ ¤گÂÙ·È Î·Ù¿ ÙÔ ÙÂÏÈÎfi ÛÙ¿‰ÈÔ Ù˘ ˘ÚÔÛ˘Ûۈ̿وÛ˘. AÓÙ›ıÂÙ· Ô ÂÎÙÚÔ¯ÈÛÌfi˜ Û ·˘Ù‹ ÙË ÌÔÚÊ‹ Ù˘ ˙ÈÚÎÔÓ›·˜ Â›Ó·È Ù·¯‡ÙÂÚÔ˜ Î·È Ù· ÎÔÙÈο ÂÚÁ·Ï›· Ô˘ Â͢ËÚÂÙÔ‡Ó ·˘Ùfi ÙÔ ÛÎÔfi ˘Ê›ÛÙ·ÓÙ·È ÌÈÎÚfiÙÂÚË ÊıÔÚ¿66. H ‰Â‡ÙÂÚË ·ÊÔÚ¿ ÙÔÓ ÂÎÙÚÔ¯ÈÛÌfi Î·È Î·Ù·Û΢‹ Ù˘ ÛÙËÓ Ï‹Úˆ˜ Û˘ÓÙËÁ̤ÓË ÌÔÚÊ‹ Ù˘ fiÙ·Ó ¤¯ÂÈ ÚÔËÁËı› Ë ¤„ËÛË Î¿Ùˆ ·fi Û˘Ì›ÂÛË (Hot Isostatic Pressing ‹ HiP) Ù˘ ˙ÈÚÎÔÓ›·˜. K‡ÚÈÔÈ ÂÎÚfiÛˆÔÈ ·˘Ù‹˜ Ù˘ Ù¯ÓÈ΋˜ Â›Ó·È Ù· Û˘ÛÙ‹Ì·Ù· DC-Zirkon (DCS Dental AG), Everest-ZH (Kavo), Denzir (Cadesthetics AB)22. H Û˘ÁÎÂÎÚÈ̤ÓË Ù¯ÓÈ΋ ÏÂÔÓÂÎÙ› ÛÙÔ ÁÂÁÔÓfi˜ fiÙÈ ÔÈ ÙÂÏÈΤ˜ ÌÔÚʤ˜ ÙˆÓ VitaYZ PSZ Table 4B. Current fully-sintered zirconia CAD-Cam systems System Material synthesis Denzir PSZ Digizon PSZ Everst ZH blanks PSZ clinical practice are the total coverage crowns, mainly because of their excellent clinical reliability over other more conservative restorations (inlays,onlays etc)71. The removal of tooth structure when preparing the tooth to receive a dental prostheses must be as conservative as possible and any construction should be made at the lowest possible volume, without violating the biological principles and the principles of mechanical strength of the structure4. The instructions, however, for making teeth that will receive crowns with zirconia core differ slightly from those of classical metal-ceramic crowns72. The minimum height of clinical crown of the tooth preparation should be at least 4mm73. Particularly, incisal or occlusal reduction of the tooth abutment should be 1.5 to 2mm and 1.2 to 1.5 mm in the axial walls. In cervical areas finish line should be slightly subgingivally and its width should be 0,8-1,2 mm74, ¶›Ó·Î·˜ 3. ∫‡ÚȘ ÂÊ·ÚÌÔÁ¤˜ Î·È ¯Ú‹ÛÂȘ ∑ÈÚÎÔÓ›· ÛÙË ‚ÈÔÌ˯·Ó›· TÌ‹Ì·Ù· ‚·Ï‚›‰ˆÓ Î·È ·ÓÙÏÈÒÓ O‰ËÁÔ› ηψ‰›ˆÓ KÔÙÈο ÂÚÁ·Ï›· M¤Û· ÙÚÈ‚‹˜ Î·È ‰È·ÛÔÚ¿˜ AÈÛıËÙ‹Ú˜ O͢ÁfiÓÔ˘ MÂÌ‚Ú¿Ó˜ ΢„ÂÏÒÓ Î·˘Û›ÌÔ˘ £ÂÚÌÈÎÔ› ÌÔÓˆÙ¤˜ EÍ·ÚÙ‹Ì·Ù· ÔÙÈÎÒÓ ÈÓÒÓ 116 Hellenic Stomatological Review 57: 101-137, 2013 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review ÛÎÂÏÂÙÒÓ ‰ÂÓ ˘Ê›ÛÙ·ÓÙ·È ÌÂÙ·‚ÔϤ˜ ‰È·ÛÙ¿ÛˆÓ, Ë ·ÔÎÔ‹ Î·È ÂÂÍÂÚÁ·Û›· fï˜ Â›Ó·È ÂÍ·ÈÚÂÙÈο ‰‡ÛÎÔÏË Î·È ¯ÚÔÓÔ‚fiÚ· ÏfiÁˆ Ù˘ ˘„ËÏ‹˜ ÛÎÏËÚfiÙËÙ·˜ ÙÔ˘ ˘ÏÈÎÔ‡66. EÍ·ÎÔÏÔ˘ı› ·ÎfiÌ· Î·È Û‹ÌÂÚ· Ó· ÌËÓ ˘¿Ú¯ÂÈ ÔÌÔʈӛ· ÌÂٷ͇ ÂÚ¢ÓËÙÒÓ Û fiÙÈ ·ÊÔÚ¿ ÙËÓ ÂÈÏÔÁ‹ ÌÂıfi‰Ô˘ ηٷÛ΢‹˜ ÛÎÂÏÂÙÒÓ ˙ÈÚÎÔÓ›·˜ Ë ÔÔ›· ı· Â›Ó·È ÏÈÁfiÙÂÚÔ Î·Ù·ÛÙÚÂÙÈ΋ ÁÈ· ÙÔ ÙÂÏÈÎfi ÚÔ˚fiÓ, ÁÈ·˘Ùfi ÂÍ·ÎÔÏÔ˘ıÔ‡Ó Ó· Û˘Ó˘¿Ú¯Ô˘Ó Î·È ÔÈ ‰‡Ô ÚÔ·Ó·ÊÂÚı›Û˜ Ù¯ÓÈΤ˜68. ™ÙÔÓ ¶›Ó·Î· 4 ÂÚÈÏ·Ì‚¿ÓÔÓÙ·È Ù· ÛËÌ·ÓÙÈÎfiÙÂÚ· Û˘ÛÙ‹Ì·Ù· CAD-CAM ÁÈ· ÂÂÍÂÚÁ·Û›· ˘ÏÈÎÒÓ ˙ÈÚÎÔÓ›·˜. ¶›Ó·Î·˜ 4A. ™‡Á¯ÚÔÓ· Û˘ÛÙ‹Ì·Ù· CAD-CAM “green stage” ™‡ÛÙËÌ· ™‡ÓıÂÛË ˘ÏÈÎÔ‡ Cercon PSZ DC-Zirkon PSZ IPS e.max ZirCAD PSZ LAVA Frame PSZ ProceraAllCeram alumina ProceraAllZirkon PSZ VitaYZ PSZ 75 . The inclination of the axial walls should be 5-6Æ73. Some clinicians suggest 2,0 to 2,5 mm incisal/occlusal reduction for better aesthetics and anatomical shape76. On the other hand, there are of course minimally invasive preparation techniques such as edge knife (knife-edge) which seem to be an alternative technique in anterior teeth, without reducing the strength of the structure77. Unlike the feather-edge preparations, deep retentive grooves and complex occlusal morphology of the abutment should be avoided because it is extremely difficult to reproduce78, 79. The specifications for the laboratory part of the construction for the core thickness is 0,5 mm for posterior teeth and to 0,3 mm for the anterior77 (Fig. 5). A different approach to design the framework for zirconia crowns is the technique of a zirconia collar80. The Ce-TZP/Al is the hardest ceramic material currently available for prosthetic restorations. The thickness of the core Ce-TPZ/Al frameworks can be reduced to 0,3 mm, compared to 0,5 mm of Y-TZP. ¶›Ó·Î·˜ 4B. ™‡Á¯ÚÔÓ· Û˘ÛÙ‹Ì·Ù· Cad-Cam “Ï‹ÚÔ˘˜ Û˘Ûۈ̿وÛ˘” ™‡ÛÙËÌ· ™‡ÓıÂÛË ˘ÏÈÎÔ‡ Denzir PSZ Digizon PSZ Everst ZH blanks PSZ EºAPMO°E™ KEPAMIKøN ZIPKONIA™ ™THN O¢ONTIATPIKH ø™ E¶ANOP£øTIKøN Y§IKøN OÈ Ô‰ÔÓÙÈΤ˜ ÚÔÛıÂÙÈΤ˜ ·ÔηٷÛÙ¿ÛÂȘ Ú¤ÂÈ Ó· Â͢ËÚÂÙÔ‡Ó ÙËÓ ÏÂÈÙÔ˘ÚÁ›·, ÙËÓ ¿ÓÂÛË ÙÔ˘ ·ÛıÂÓÔ‡˜ Î·È ÙËÓ ‰È·Ù‹ÚËÛË Ù˘ ·ÎÂÚ·ÈfiÙËÙ¿˜ ÙÔ˘˜ Û ‚¿ıÔ˜ ¯ÚfiÓÔ˘70. H ÂÈÏÔÁ‹ ÏÔÈfiÓ ÙˆÓ Î·Ù¿ÏÏËÏˆÓ ˘ÏÈÎÒÓ Ú¤ÂÈ Ó· Á›ÓÂÙ·È Ì ÁÓÒÌÔÓ· ÙËÓ ÂÈÙ˘¯›· Ù˘ ·ÔηٿÛÙ·Û˘. T· ÎÂÚ·ÌÈο ˙ÈÚÎÔÓ›·˜ ¤¯Ô˘Ó ·ÍÈÔÔÈËı› Û ÌÈ· ·ÚÎÂÙ¿ ÌÂÁ¿ÏË Áο̷ ÂÊ·ÚÌÔÁÒÓ ÛÙËÓ Ô‰ÔÓÙÈ·ÙÚÈ΋. ™˘ÓÂÒ˜ Ì·˙› Ì ٷ ̤ٷÏÏ· Î·È ¿ÏÏ· ÔÏÔÎÂÚ·ÌÈο Û˘ÛÙ‹Ì·Ù· ÚÔÛı¤ÙÔ˘Ó ÌÈ· ÂÓ·ÏÏ·ÎÙÈ΋ ÚÔÛ¤ÁÁÈÛË Û ηٷÛ΢¤˜ fiÔ˘ Ë ·ÓÙÔ¯‹ Û˘Ó‰˘¿˙ÂÙ·È Ì ·˘ÍË̤Ó˜ ··ÈÙ‹ÛÂȘ ÁÈ· ·ÈÛıËÙÈ΋. Hellenic Stomatological Review 57: 101-137, 2013 Fig. 5: Zirconia crown. Visible are the extended dimensions of zirconia core After three years of clinical studies81 zirconia crowns seem to have satisfactory levels of success, to the point that the zirconia core is considered as a reliable alternative material to the metal framework82. To reduce the rate of ceramic chipping, a ceramic veneering material with suitable thermal expansion coefficient compatible with that of zirconia was tested and the three-year follow-up showed excellent behavior83. Also, after two years follow-up it was found that the use of core material reinforced with alumina zirconia by 25% (In Ceram Zirconia-VITA) is equally reliable for the manufacture of posterior teeth crowns with Cercon Zirconia84. Similar encouraging results for the InCeram Zirconia have been published in a three year study85. However, for a more accurate assessment of the clinical behavior and complications of the use of allceramic crowns with zirconia core, a significant number of at least five-year studies86 should be completed and be able to support the use of zirconia ceramics as reliable alternative to conventional metal-prostheses85. 117 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review MONHPEI™ O¢ONTIKE™ A¶OKATA™TA™EI™ TÔ ÌÂÁ·Ï‡ÙÂÚÔ fiÁÎÔ ÌÂÌÔÓˆÌ¤ÓˆÓ ·ÔηٷÛÙ¿ÛÂˆÓ ÛÙËÓ ÎÏÈÓÈ΋ Ú¿ÍË ·ÔÙÂÏÔ‡Ó ÔÈ ÛÙÂÊ¿Ó˜ ÔÏÈ΋˜ Î¿Ï˘„˘ ÂÍ·ÈÙ›·˜ ΢ڛˆ˜ Ù˘ ÂÍ·ÈÚÂÙÈ΋˜ ÎÏÈÓÈ΋˜ ·ÍÈÔÈÛÙ›·˜ ÙÔ˘˜ Û ۯ¤ÛË Ì ¿ÏϘ ÂÚÈÛÛfiÙÂÚÔ Û˘ÓÙËÚËÙÈΤ˜ ÌÔÓ‹ÚÂȘ ·ÔηٷÛÙ¿ÛÂȘ71. H ·Ê·›ÚÂÛË ÙˆÓ Ô‰ÔÓÙÈÎÒÓ ÈÛÙÒÓ Î·Ù¿ ÙËÓ ·Ú·Û΢‹ ÙˆÓ ‰ÔÓÙÈÒÓ ÁÈ· ÙËÓ ˘Ô‰Ô¯‹ ÚÔÛıÂÙÈÎÒÓ ÂÚÁ·ÛÈÒÓ Ú¤ÂÈ Ó· ‚Ú›ÛÎÂÙ·È Ì¤Û· ÛÙ· Ï·›ÛÈ· ÙˆÓ ÚԉȷÁÚ·ÊÒÓ Î¿ı ηٷÛ΢‹˜, ÒÛÙ ӷ Á›ÓÂÙ·È Î·Ù¿ ÙÔÓ ÂÏ¿¯ÈÛÙÔ ‰˘Ó·Ùfi fiÁÎÔ, ¯ˆÚ›˜ Ó· ·Ú·‚È¿˙ÔÓÙ·È ÔÈ ‚ÈÔÏÔÁÈΤ˜ ·Ú¯¤˜ Ù˘ ÂÊ·ÚÌÔÁ‹˜ Î·È ÔÈ Ì˯·ÓÈΤ˜ ·Ú¯¤˜ Ù˘ ·ÓÙÔ¯‹˜ Ù˘ ηٷÛ΢‹˜4. OÈ Ô‰ËÁ›Â˜ ¿ÓÙˆ˜ ÁÈ· ÙËÓ ·Ú·Û΢‹ ‰ÔÓÙÈÒÓ Ô˘ ı· ˘Ô‰Â¯ıÔ‡Ó ÛÙÂÊ¿ÓË Ì ˘Ú‹Ó· ˙ÈÚÎÔÓ›·˜ ¤¯Ô˘Ó ÌÈÎÚ¤˜ ‰È·ÊÔÚ¤˜ ·fi ·˘Ù¤˜ ÙˆÓ ÎÏ·ÛÈÎÒÓ ÌÂÙ·ÏÏÔÎÂÚ·ÌÈÎÒÓ ÛÙÂÊ·ÓÒÓ72. TÔ ÂÏ¿¯ÈÛÙÔ ‡„Ô˜ ÎÏÈÓÈ΋˜ ̇Ï˘ ÙÔ˘ ˘fi ·Ú·Û΢‹ ‰ÔÓÙÈÔ‡ Ú¤ÂÈ Ó· Â›Ó·È 4mm73. ¶ÈÔ Û˘ÁÎÂÎÚÈ̤ӷ ¯ÚÂÈ¿˙ÂÙ·È 1,5 ¤ˆ˜ 2mm ÎÔÙÈ΋ ‹ Ì·ÛËÙÈ΋ ٷ›ӈÛË ÙÔ˘ ÛÙËÚ›ÁÌ·ÙÔ˜ Î·È 1,2 ¤ˆ˜ 1,5mm ·Ê·›ÚÂÛË ÛÙ· ·ÍÔÓÈο ÙÔȯÒÌ·Ù·. ™ÙȘ ·˘¯ÂÓÈΤ˜ ·ÔÏ‹ÍÂȘ Ë ÔÚÈÔı¤ÙËÛË Ú¤ÂÈ Ó· Á›ÓÂÙ·È ÂÏ·ÊÚÒ˜ ÂÓ‰ÔÛ¯ÈÛÌÈο Î·È ÙÔ Â‡ÚÔ˜ ÙÔÍÔÂȉԇ˜ ·fiÏË͢ ÛÙ· ·˘¯ÂÓÈο fiÚÈ· 0,8 ¤ˆ˜ 1,2mm73, 74. H ÎÏ›ÛË ÙˆÓ ·ÍÔÓÈÎÒÓ ÙÔȯˆÌ¿ÙˆÓ Ú¤ÂÈ Ó· Â›Ó·È 5-6Æ73. OÚÈṲ̂ÓÔÈ ÎÏÈÓÈÎÔ› Ô‰ÔÓÙ›·ÙÚÔÈ Û˘ÓÈÛÙÔ‡Ó 2,0 ¤ˆ˜ 2,5mm ÎÔÙÈ΋/Ì·ÛËÙÈ΋ ٷ›ӈÛË ÁÈ· ηχÙÂÚË ÔÙÈ΋ ·fi‰ÔÛË Î·È ·Ó·ÙÔÌÈ΋ ÌÔÚÊ‹76. Afi ÙËÓ ¿ÏÏË ÏÂ˘Ú¿ ˘¿Ú¯Ô˘Ó ‚¤‚·È· Î·È ÔÈ ÂÏ¿¯ÈÛÙ· ÂÂÌ‚·ÙÈΤ˜ Ù¯ÓÈΤ˜ ·Ú·Û΢‹˜ fiˆ˜ ·˘Ù‹˜ ÙÔ˘ ¿ÎÚÔ˘ Ì·¯·›Ú·˜ (knife-edge) Ô˘ Ê·›ÓÂÙ·È Ó· ·ÔÙÂÏÔ‡Ó ÂÓ·ÏÏ·ÎÙÈ΋ Ù¯ÓÈ΋ Û ÚfiÛıÈ· ‰fiÓÙÈ·, ¯ˆÚ›˜ Ó· ÌÂÈÒÓÂÙ·È Ë ·ÓÙÔ¯‹ Ù˘ ηٷÛ΢‹˜77. AÓÙ›ıÂÙ· Ù· fiÚÈ· ¿ÎÚÔ˘ ÊÙÂÚÔ‡ (feather-edge), ÔÈ ‚·ıȤ˜ Û˘ÁÎÚ·ÙËÙÈΤ˜ ·‡Ï·Î˜ Î·È Ë Û‡ÓıÂÙË Ì·ÛËÙÈ΋ ÌÔÚÊÔÏÔÁ›· ÙÔ˘ ÎÔÏÔ‚ÒÌ·ÙÔ˜ ı· Ú¤ÂÈ Ó· ·ÔʇÁÔÓÙ·È, ‰ÈfiÙÈ Â›Ó·È ÂÍ·ÈÚÂÙÈο ‰‡ÛÎÔÏÔ Ó· ·Ó··Ú·¯ıÔ‡Ó78, 79. OÈ ÚԉȷÁڷʤ˜ Ô˘ ·ÊÔÚÔ‡Ó ÛÙÔ ÂÚÁ·ÛÙËÚÈ·Îfi ̤ÚÔ˜ Ù˘ ηٷÛ΢‹˜ ÁÈ· ÙÔ ¿¯Ô˜ ÙÔ˘ ˘Ú‹Ó· Â›Ó·È 0,5mm ÁÈ· Ù· Ô›ÛıÈ· ‰fiÓÙÈ· Î·È ¤ˆ˜ 0,3mm ÁÈ· Ù· ÚfiÛıÈ·77 (EÈÎ. 5). M›· ‰È·ÊÔÚÂÙÈ΋ Û¯Â- EÈÎ. 5: OÏÔÎÏËڈ̤ÓË ÛÙÂÊ¿ÓË ˙ÈÚÎÔÓ›·˜ Ì ۷Ê›˜ ÙȘ ‰È·ÛÙ¿ÛÂȘ ÙÔ˘ ÛÎÂÏÂÙÔ‡ ˙ÈÚÎÔÓ›·˜ 118 The use of all-ceramic crowns as abutments for removable prostheses rarely appears in the dental literature. The design of these crowns should provide retentive undercuts and slots87. Zirconia crowns have been used in removable prosthodontics as crowns for the support of partial dentures87 or as primary crowns in dual crown systems (telescopic substructures)88. One potential disadvantage arises from the fact that with this type of restorations, zirconia is in some parts completely exposed to the oral environment, without the necessary ceramic veneer coverage. This constitutes a danger to the integrity of the restorations over time, considering the role of water in aging of zirconia89. The manufacturers, however, recommend polishing of the exposed zirconia ceramics with extremely fine abrasives87. ALL CERAMIC FIXED PARTIAL DENTURESSPECIFICATIONS A fixed partial denture (FPD) prosthesis consists of abutments and pontics, which are connected together by connectors. The connector is a relatively thin, vulnerable point of the prosthetic construction90. During the loading of fixed partial dentures, connectors reach critical stresses before these stresses reach the thicker parts of the prostheses. For this reason, the connectors are manufactured in appropriate dimensions to withstand occlusal loads4. Especially for zirconia restorations connectors design seems to be crucial for the flexural strength and reliability of zirconia fixed partial dentures66. Increasing the dimensions of the connector reduces stress concentration at critical points of the structure impacting positively on the strength of ceramic construction90. It is suggested the height of 4mm is sufficient for posterior teeth FPD’s and even greater if it is placed in areas of increased loads (bruxism or increased vertical overlap). A similar design is not always possible due to biological constraints (clinical crown height, interdental spaces). Some researchers suggest connector dimensions 3x3 mm and 0.5 mm core thickness with positive laboratory results91, while others increase dimensions up to 4x4 mm92. However, to avoid connector fractures (Fig. 6) and therefore zirconia core FPD’s clinical failures there is need for proper planning and proportional connector geometry to resist the loads sustained during function (Fig. 7). Of particular importance are the minimum diameter of the connector (dmin) and the radius of curvature in cross section. Clinically the design should take into account the material properties, the anatomical constraints, and the possibility of oral hygiene and aesthetic expectations66. Proper design of connector offers longevity to the prosthetic restorations. Increasing the connector height from 3 to 4mm significantly reduced the stress concentration93 (Fig. 8). According to Studart94 3-unit FPD’s should have a connector cross-sectional area of 5,7 mm2, 4-unit 12,6 mm2 and 5-unit 18,8 mm2. Forces that have a special role in connector fractures are the tensile forces developed during function of the FPD during chewing. Hellenic Stomatological Review 57: 101-137, 2013 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review ‰È·ÛÙÈ΋ ÚÔÛ¤ÁÁÈÛË ÙÔ˘ ÛÎÂÏÂÙÔ‡ ˙ÈÚÎÔÓ›·˜ ÁÈ· ÌÔÓ‹ÚÂȘ ÛÙÂÊ¿Ó˜ Â›Ó·È Ë Ù¯ÓÈ΋ Ù˘ ·Ú·ÌÔÓ‹˜ ÂÓfi˜ ÎÔÏÏ¿ÚÔ˘ ˙ÈÚÎÔÓ›·˜80. TÔ ÎÂÚ·ÌÈÎfi Ce-TZP/Al Â›Ó·È ÙÔ ÛÎÏËÚfiÙÂÚÔ ÎÂÚ·ÌÈÎfi ˘ÏÈÎfi Û‹ÌÂÚ· ‰È·ı¤ÛÈÌÔ ÁÈ· ÚÔÛıÂÙÈΤ˜ ·ÔηٷÛÙ¿ÛÂȘ. TÔ ¿¯Ô˜ ÙÔ˘ ˘Ú‹Ó· ÙˆÓ ÎÂÚ·ÌÈÎÒÓ Ce-TZP/Al ÛÎÂÏÂÙÒÓ ÌÔÚ› Ó· ÌÂȈı› ÛÙÔ 0,3 mm, Û ۇÁÎÚÈÛË Ì 0,5 mm ÙˆÓ ÎÂÚ·ÌÈÎÒÓ Y-TZP. MÂÙ¿ ·fi ÙÚÈÂÙ›˜ ÎÏÈÓÈΤ˜ ÌÂϤÙ˜81 ÔÈ ÛÙÂÊ¿Ó˜ Ê·›ÓÂÙ·È Ó· ·ÚÔ˘ÛÈ¿˙Ô˘Ó ÈηÓÔÔÈËÙÈο ÔÛÔÛÙ¿ ÂÈÙ˘¯›·˜, Û ÛËÌÂ›Ô Ô˘ Ó· ıˆÚÂ›Ù·È Ë ˙ÈÚÎÔÓ›· ˆ˜ ÂÓ·ÏÏ·ÎÙÈ΋ χÛË ÛÙÔ ÌÂÙ·ÏÏÈÎfi ÛÎÂÏÂÙfi82. °È· ÙË Ì›ˆÛË ÙÔ˘ ÔÛÔÛÙÔ‡ Ù˘ ·ÔÊÏÔ›ˆÛ˘ ‰ÔÎÈÌ¿ÛÙËΠ¤Ó· ÂÈÎ·Ï˘ÙÈÎfi ÎÂÚ·ÌÈÎfi Ì ÙÔÓ Î·Ù¿ÏÏËÏÔ Û˘ÓÙÂÏÂÛÙ‹ ıÂÚÌÈ΋˜ ‰È·ÛÙÔÏ‹˜ Û˘Ì‚·Ùfi Ì ÂΛÓÔÓ Ù˘ ˙ÈÚÎÔÓ›·˜ Î·È Û ÙÚÈÂÙ‹ ·Ú·ÎÔÏÔ‡ıËÛË ¤‰ÂÈÍ ÂÍ·ÈÚÂÙÈ΋ Û˘ÌÂÚÈÊÔÚ¿83. E›Û˘ Û ‰ÈÂÙ‹ ·Ú·ÎÔÏÔ‡ıËÛË ‰È·ÈÛÙÒıËΠfiÙÈ Ë ¯Ú‹ÛË ˘ÏÈÎÔ‡ ˘Ú‹Ó· ·ÏÔ˘Ì›Ó·˜ ÂÓÈÛ¯˘Ì¤Ó˘ Ì ˙ÈÚÎÔÓ›· ηٿ 25% (In Ceram Zirconia-VITA, Germany) Â›Ó·È ÂÍ›ÛÔ˘ ·ÍÈfiÈÛÙË ÁÈ· ÙËÓ Î·Ù·Û΢‹ ÛÙÂÊ·ÓÒÓ ÔÈÛı›ˆÓ ‰ÔÓÙÈÒÓ Ì ÙËÓ Cercon Zirconia84. ¶·ÚfiÌÔÈ· ÂÓı·ÚÚ˘ÓÙÈο ·ÔÙÂϤÛÌ·Ù· ÁÈ· ÙÔ In-Ceram Zirconia ¤¯Ô˘Ó ‰ËÌÔÛÈ¢ı› Î·È Û ÙÚÈÂÙ‹ ÌÂϤÙË85. ¶¿ÓÙˆ˜ ÁÈ· Ó· ˘¿ÚÍÂÈ ÔÚıfiÙÂÚË ·ÍÈÔÏfiÁËÛË Ù˘ ÎÏÈÓÈ΋˜ Û˘ÌÂÚÈÊÔÚ¿˜ Î·È ÙˆÓ ÂÈÏÔÎÒÓ ·fi ÙË ¯Ú‹ÛË ÔÏÔÎÂÚ·ÌÈÎÒÓ ÛÙÂÊ·ÓÒÓ Ì ˘Ú‹Ó· ˙ÈÚÎÔÓ›·˜ ı· Ú¤ÂÈ Ó· ÔÏÔÎÏËÚˆı› ÛËÌ·ÓÙÈÎfi˜ ·ÚÈıÌfi˜ ÂÓÙ·ÂÙÒÓ ÌÂÏÂÙÒÓ86 Î·È Ó· ÌÔÚ¤ÛÂÈ Ó· ÛÙËÚȯı› Ë ¿Ô„Ë fiÙÈ ·ÔÙÂÏÔ‡Ó ·ÍÈfiÈÛÙË ÂÓ·ÏÏ·ÎÙÈ΋ χÛË ÛÙȘ Û˘Ì‚·ÙÈΤ˜ ÌÂÙ·ÏÏÔÎÂÚ·ÌÈΤ˜ ÚÔÛıÂÙÈΤ˜ ÂÚÁ·Û›Â˜85. H ¯Ú‹ÛË ÙˆÓ ÔÏÔÎÂÚ·ÌÈÎÒÓ ÛÙÂÊ·ÓÒÓ ÁÈ· ÛÙËÚ›ÁÌ·Ù· ÎÈÓËÙÒÓ ÚÔÛı¤ÛÂˆÓ Û¿ÓÈ· ÂÌÊ·Ó›˙ÂÙ·È ÛÙËÓ Ô‰ÔÓÙÈ·ÙÚÈ΋ ‚È‚ÏÈÔÁÚ·Ê›·. O ۯ‰ȷÛÌfi˜ ·˘ÙÒÓ ÙˆÓ ÛÙÂÊ·ÓÒÓ Ú¤ÂÈ Ó· ·Ú¤¯ÂÈ ÙȘ ·Ó¿ÏÔÁ˜ Û˘ÁÎÚ·ÙËÙÈΤ˜ ˘ÔÛηʤ˜, Ô‰ËÁ¿ ›‰· Î·È ˘Ô‰Ô¯¤˜ ÂÊ·Ù‹ÚˆÓ87. Œ¯ÂÈ ·Ó·ÊÂÚı› Ë ¯Ú‹ÛË ÛÙÂÊ·ÓÒÓ ˙ÈÚÎÔÓ›·˜ ÛÙËÓ ÎÈÓËÙ‹ ÚÔÛıÂÙÈ΋ ηıÒ˜ ¤¯Ô˘Ó ¯ÚËÛÈÌÔÔÈËı› ˆ˜ ÛÙÂÊ¿Ó˜ ‰ÔÓÙÈÒÓ ÛÙËÚÈÁÌ¿ÙˆÓ ÌÂÚÈÎÒÓ Ô‰ÔÓÙÔÛÙÔȯÈÒÓ87 ‹ ˆ˜ ÚˆÙÔÁÂÓ›˜ ÛÙÂÊ¿Ó˜ ÛÂ Û˘ÛÙ‹Ì·Ù· ‰ÈÏÒÓ ÛÙÂÊ·ÓÒÓ (ÙËÏÂÛÎÔÈΤ˜ ÎÈÓËÙ¤˜ ηٷÛ΢¤˜)88. ŒÓ· Èı·Ófi ÌÂÈÔÓ¤ÎÙËÌ· ÚÔ·ÙÂÈ ·fi ÙÔ ÁÂÁÔÓfi˜ fiÙÈ Û ·˘ÙÔ‡ ÙÔ˘ Ù‡Ô˘ ÙȘ ÛÙÂÊ¿Ó˜, ÙÔ ˘ÏÈÎfi Ù˘ ˙ÈÚÎÔÓ›·˜ ÙÔ˘ ˘Ú‹Ó· Â›Ó·È Û ÔÚÈṲ̂ӷ ÛËÌ›· ÂÓÙÂÏÒ˜ ÂÎÙÂıÂÈ̤ÓÔ ÛÙÔ ÛÙÔÌ·ÙÈÎfi ÂÚÈ‚¿ÏÏÔÓ ¯ˆÚ›˜ ÎÂÚ·ÌÈ΋ Î¿Ï˘„Ë. H ¤ÎıÂÛË ·˘Ù‹ ·ÔÙÂÏ› ΛӉ˘ÓÔ ÁÈ· ÙËÓ ·ÎÂÚ·ÈfiÙËÙ· ÙˆÓ ·ÔηٷÛÙ¿ÛÂˆÓ Û ‚¿ıÔ˜ ¯ÚfiÓÔ˘ ηıÒ˜ Â›Ó·È ·Ô‰Â‰ÂÈÁ̤ÓË Ë Û˘Ì‚ÔÏ‹ Ù˘ ·ÚÔ˘Û›·˜ ÓÂÚÔ‡ ÛÙËÓ ÂÈÙ¿¯˘ÓÛË ÙÔ˘ Ê·ÈÓÔ̤ÓÔ˘ Ù˘ Á‹Ú·ÓÛ˘ Ù˘ ˙ÈÚÎÔÓ›·˜89. OÈ Î·Ù·Û΢·ÛÙ¤˜ ¿ÓÙˆ˜ Û˘ÓÈÛÙÔ‡Ó ÙË Ï›·ÓÛË Ù˘ ÂÎÙÂıÂÈ̤Ó˘ ˙ÈÚÎÔÓ›·˜ Ì ÂÍ·ÈÚÂÙÈο ÏÂÙfiÎÔÎη ÎÂÚ·ÌÈο ÏÂÈ·ÓÙÈο ̤۷87. Fig. 6: Extended dimensions of zirconia core Fig.7: Crack of zirconia core in a 4 unit bridge O§OKEPAMIKE™ °EºYPE™ - ¶PO¢IA°PAºE™ M›· ·Î›ÓËÙË ÚÔÛıÂÙÈ΋ ·ÔηٿÛÙ·ÛË ·ÔÙÂÏÂ›Ù·È ·fi Ù· ÛÙËÚ›ÁÌ·Ù· Î·È Ù· ÁÂÊ˘ÚÒÌ·Ù·, Ù· ÔÔ›· Û˘Ó‰¤ÔÓÙ·È ÌÂٷ͇ ÙÔ˘˜ Ì ÙÔ˘˜ Û˘Ó‰¤ÛÌÔ˘˜. O Û‡Ó‰ÂÛÌÔ˜ ·ÔÙÂÏ› ¤Ó· Û¯ÂÙÈο ÏÂÙfi, ¢¿ÏˆÙÔ ÛËÌÂ›Ô ÌÈ·˜ ÌË ÔÌÔÈfiÌÔÚÊÔ˘ Û¯‹Ì·ÙÔ˜ ηٷÛ΢‹˜90. K·Ù¿ ÙË ‰È¿ÚÎÂÈ· Ù˘ ÊfiÚÙÈÛ˘ ÌÈ·˜ Á¤Ê˘Ú·˜ Ô Û‡Ó‰ÂÛÌÔ˜ ÊÙ¿ÓÂÈ Û ÎÚ›ÛÈ̘ Hellenic Stomatological Review 57: 101-137, 2013 Fig. 8: The previous apperture in backscattered electron image (BEI 20X) (Tzoutzas and Tzanakakis 2010) 119 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review Ù¿ÛÂȘ ÚÈÓ ·fi Ù· ·¯‡ÙÂÚ· ÛËÌ›· Ù˘ ηٷÛ΢‹˜. °È· ÙÔ ÏfiÁÔ ·˘Ùfi ÔÈ Û‡Ó‰ÂÛÌÔÈ Î·Ù·Û΢¿˙ÔÓÙ·È Û ηٿÏÏËϘ ‰È·ÛÙ¿ÛÂȘ ÒÛÙ ӷ ·ÓÙ¤¯Ô˘Ó Ù· Ì·ÛËÙÈο ÊÔÚÙ›·4. EȉÈο ÁÈ· ÙȘ ·ÔηٷÛÙ¿ÛÂȘ ˙ÈÚÎÔÓ›·˜ Ô Û¯Â‰È·ÛÌfi˜ ÙÔ˘ Û˘Ó‰¤ÛÌÔ˘ Ê·›ÓÂÙ·È Ó· Â›Ó·È Î·ıÔÚÈÛÙÈÎfi˜ ÁÈ· ÙËÓ ·ÓÙÔ¯‹ ÛÙË ıÚ·‡ÛË Î·È ÙËÓ ‚ȈÛÈÌfiÙËÙ· ÙˆÓ ÁÂÊ˘ÚÒÓ Ì ÛÎÂÏÂÙfi ˙ÈÚÎÔÓ›·˜66. A˘Í¿ÓÔÓÙ·˜ ÙȘ ‰È·ÛÙ¿ÛÂȘ ÙˆÓ Û˘Ó‰¤ÛÌˆÓ ÌÂÈÒÓÂÙ·È Ë Û˘ÁΤÓÙÚˆÛË Ù¿ÛÂˆÓ Û ÎÚ›ÛÈÌ· ÛËÌ›· Ù˘ ‰ÔÎÔ‡ ÂȉÚÒÓÙ·˜ ıÂÙÈο ÛÙËÓ ·ÓÙÔ¯‹ Ù˘ ÔÏÔÎÂÚ·ÌÈ΋˜ ηٷÛ΢‹˜90. ¶ÚÔÙ›ÓÂÙ·È Ì¿ÏÈÛÙ· ÙÔ ‡„Ô˜ ÙˆÓ 4mm ˆ˜ ·ÚΤ˜ ÁÈ· Á¤Ê˘Ú˜ ÔÈÛı›ˆÓ ‰ÔÓÙÈÒÓ ‹ ·ÎfiÌË ÌÂÁ·Ï‡ÙÂÚÔ ·Ó ÚfiÎÂÈÙ·È ÁÈ· ÂÚÈÙÒÛÂȘ ·˘ÍË̤Ó˘ ÊfiÚÙÈÛ˘ fiˆ˜ Û ‚ÚÔ˘ÍÈÛÙ¤˜ ‹ ·˘ÍË̤ÓË Î·Ù·ÎfiÚ˘ÊË ÚfiÙ·ÍË. ŒÓ·˜ ·ÚfiÌÔÈÔ˜ ۯ‰ȷÛÌfi˜ ‰ÂÓ Â›Ó·È ¿ÓÙ· ÂÊÈÎÙfi˜ ÏfiÁˆ ‚ÈÔÏÔÁÈÎÒÓ ÂÚÈÔÚÈÛÌÒÓ (‡„Ô˜ ÎÏÈÓÈ΋˜ ̇Ï˘, ÌÂÛÔ‰fiÓÙÈ· ‰È·ÛÙ‹Ì·Ù·). OÚÈṲ̂ÓÔÈ ÂÚ¢ÓËÙ¤˜ ÚÔÙ›ÓÔ˘Ó ‰È·ÛÙ¿ÛÂȘ Û˘Ó‰¤ÛÌÔ˘ 3x3 mm Î·È ¿¯Ô˜ ÛÎÂÏÂÙÔ‡ 0.5mm Ì ıÂÙÈο ÂÚÁ·ÛÙËÚȷο ·ÔÙÂϤÛÌ·Ù·91, ÂÓÒ ¿ÏÏÔÈ Û˘ÓÈÛÙÔ‡Ó ÌÂÁ·Ï‡ÙÂÚ˜ ‰È·ÛÙ¿ÛÂȘ Ù˘ Ù¿Í˘ ÙˆÓ 4x4 mm92. ¶¿ÓÙˆ˜ ÁÈ· Ó· ·ÔʇÁÔÓÙ·È Î·Ù¿ÁÌ·Ù· Û˘Ó‰¤ÛÌˆÓ Î·È Û˘ÓÂÒ˜ ÎÏÈÓÈΤ˜ ·ÔÙ˘¯›Â˜ ÁÂÊ˘ÚÒÓ Ì ˘Ú‹Ó· ˙ÈÚÎÔÓ›·˜, ¯ÚÂÈ¿˙ÂÙ·È Î·Ù¿ÏÏËÏÔ˜ ۯ‰ȷÛÌfi˜ Î·È ·Ó¿ÏÔÁË ÁˆÌÂÙÚ›· Û˘Ó‰¤ÛÌÔ˘ ÁÈ· Ó· ·ÓÙ·ÔÎÚÈı› Ô Û‡Ó‰ÂÛÌÔ˜ ÛÙ· ÊÔÚÙ›· Ô˘ ˘Ê›ÛÙ·Ù·È Î·Ù¿ ÙË ÏÂÈÙÔ˘ÚÁ›· ÙÔ˘ (EÈÎ. 6). I‰È·›ÙÂÚË ÛËÌ·Û›· ÂÎÙfi˜ Ù˘ ÂÏ¿¯ÈÛÙ˘ ‰È·Ì¤ÙÚÔ˘ ÙÔ˘ Û˘Ó‰¤ÛÌÔ˘ (dmin) ¤¯ÂÈ Î·È Ë ·ÎÙ›Ó· Î·Ì˘ÏfiÙËÙ·˜ ÛÙË ‰È·ÙÔÌ‹ ÙÔ˘˜. (EÈÎ. 7). Afi ÎÏÈÓÈ΋˜ ¿Ô„˘ ÛÙÔ Û¯Â‰È·ÛÌfi Ú¤ÂÈ Ó· Ï·Ì‚¿ÓÔÓÙ·È ˘fi„Ë ÔÈ È‰ÈfiÙËÙ˜ ÙÔ˘ ˘ÏÈÎÔ‡, ÔÈ ·Ó·ÙÔÌÈÎÔ› ÂÚÈÔÚÈÛÌÔ›, Ë ‰˘Ó·ÙfiÙËÙ· ÛÙÔÌ·ÙÈ΋˜ ˘ÁÈÂÈÓ‹˜ Î·È ·ÈÛıËÙÈΤ˜ ÚÔÛ‰Ô˘66. O ÛˆÛÙfi˜ ۯ‰ȷÛÌfi˜ ÙˆÓ Û˘Ó‰¤ÛÌˆÓ ÌÈ·˜ ·Î›ÓËÙ˘ ·ÔηٿÛÙ·Û˘ ÚÔÛ‰›‰ÂÈ Ì·ÎÚÔ‚ÈfiÙËÙ· ÛÙËÓ Î·Ù·Û΢‹. A˘Í¿ÓÔÓÙ·˜ ÙÔ ‡„Ô˜ ÙˆÓ Û˘Ó‰¤ÛÌˆÓ Û ÔÏÔÎÂÚ·ÌÈΤ˜ ·ÔηٷÛÙ¿ÛÂȘ ·fi 3 Û 4mm ÌÂÈÒÓÂÙ·È ÛËÌ·ÓÙÈο Ë Û˘ÁΤÓÙÚˆÛË Ù¿ÛÂˆÓ ÛÙÔ˘˜ Û˘Ó‰¤ÛÌÔ˘˜93 (EÈÎ. 8). ™‡Ìʈӷ Ì ÙÔÓ Studart94 Ë ·ÔηٿÛÙ·ÛË ÙÚÈÒÓ ÙÂÌ·¯›ˆÓ Ú¤ÂÈ Ó· ¤¯ÂÈ ‰È·ÙÔÌ‹ Û˘Ó‰¤ÛÌÔ˘ ÂÌ‚·‰fi 5,7 mm2,ÙˆÓ ÙÂÛÛ¿ÚˆÓ 12,6 mm2 Î·È ÙˆÓ ¤ÓÙ 18,8 mm2. ¢˘Ó¿ÌÂȘ Ô˘ ¤¯Ô˘Ó ȉȷ›ÙÂÚÔ ÚfiÏÔ ÛÙ· ηٿÁÌ·Ù· Û˘Ó‰¤ÛÌˆÓ Â›Ó·È ÔÈ ÂÊÂÏ΢ÛÙÈΤ˜ ‰˘Ó¿ÌÂȘ Ô˘ ·Ó·Ù‡ÛÛÔÓÙ·È Î·Ù¿ ÙË ÏÂÈÙÔ˘ÚÁ›· Ù˘ Á¤Ê˘Ú·˜ Ì ÙËÓ Â›‰Ú·ÛË ÙˆÓ Ì·ÛËÙÈÎÒÓ ‰˘Ó¿ÌÂˆÓ ÛÙË ÛÙÔÌ·ÙÈ΋ ÎÔÈÏfiÙËÙ·. H ̤ÁÈÛÙË ÂÊÂÏ΢ÛÙÈ΋ ÊfiÚÙÈÛË ·Ú·ÙËÚÂ›Ù·È ÛÙËÓ Ô˘ÏÈ΋ ÂÈÊ¿ÓÂÈ· ÙˆÓ Û˘Ó‰¤Û̈Ó93 ÁÈ’ ·˘Ùfi Î·È ÚÔÙ¿ıËÎÂ Ë ÌË Î¿Ï˘„Ë Ù˘ Ô˘ÏÈ΋˜ ÂÈÊ¿ÓÂÈ·˜ ÙÔ˘ Û˘Ó‰¤ÛÌÔ˘ ÌÂ Î·Ï˘ÙÈ΋ ÔÚÛÂÏ¿ÓË95. H ÂÎÙÂıÂÈ̤ÓË ÂÈÊ¿ÓÂÈ· ˙ÈÚÎÔÓ›·˜ fï˜ ‰ËÌÈÔ˘ÚÁ› ÚÔ‚ÏËÌ·ÙÈÛÌÔ‡˜ ˆ˜ ÚÔ˜ ÙË Á‹Ú·ÓÛË ‹ ·ÎÚÈ‚¤ÛÙÂÚ· ÙÔÓ ÂÎÊ˘ÏÈÛÌfi ÙˆÓ Ì˯·ÓÈÎÒÓ È‰ÈÔÙ‹ÙˆÓ Û ˘ÁÚfi ÂÚÈ‚¿ÏÏÔÓ (LTD-low temperature degradation) ÛÙÔ ÛÙÔÌ·ÙÈÎfi ÂÚÈ‚¿ÏÏÔÓ89. IηÓÔÔÈËÙÈο ÔÛÔÛÙ¿ ÂÈÙ˘¯›·˜ ¤¯Ô˘Ó ‚ÚÂı› Û ÙÚÈÂÙ‹ ·Ú·ÎÔÏÔ‡ıËÛË ÁÂÊ˘ÚÒÓ ˙ÈÚÎÔÓ›·˜ ÙÚÈÒÓ Î·È ÙÂÛÛ¿ÚˆÓ ÙÂÌ·¯›ˆÓ Ì ÌÔÓ·‰ÈÎfi ÌÂÈÔÓ¤ÎÙËÌ· ¤Ó· ÌÈÎÚfi ÔÛÔÛÙfi ·ÔÊÏÔ›ˆÛ˘ ÙÔ˘ ÂÈÎ·Ï˘ÙÈÎÔ‡ ÎÂÚ·ÌÈÎÔ‡96. ¶·Ú¿ ÙËÓ ·Ú¯È΋ ‰˘ÛÈÛÙ›· ÙˆÓ ÎÏÈÓÈÎÒÓ Ô‰ÔÓÙÈ¿ÙÚˆÓ ˆ˜ ÚÔ˜ ÙËÓ ·ÎÚ›‚ÂÈ· ÔÚȷ΋˜ ÂÊ·ÚÌÔÁ‹˜ ÙˆÓ ÔÏÔÎÂÚ·ÌÈÎÒÓ ÁÂÊ˘ÚÒÓ, Û‹ÌÂÚ· ÂÎÙÈÌ¿Ù·È fiÙÈ ‰ÂÓ ˘Ê›ÛÙ·Ù·È ‰È·120 The maximum tensile loads are observed in the gingival surface of connectors93 and for this reason non ceramic coverage of the connector’s gingival surface has been proposed95. The exposed zirconia surface, however, raises concerns regarding aging or rather degradation of mechanical properties in humid environment (LTD-low temperature degradation) in the oral environment89. Satisfactory success rates have been reported in studies with three year follow-ups of zirconia 3- and 4-unit FPD’s, without significant complications apart from only a small percentage of ceramic chipping96. Despite the initial skepticism of clinicians as to the accuracy of fit of all-ceramic FPD’s, currently it is estimated that there is no difference in quality between the application of classic metal-ceramic and modern CAD-CAM zirconia restorations97. Laboratory studies have identified the clinically acceptable fit accuracy of 3- and 4-units zirconia FPD’s fabricated on CAD-CAM systems98, 99, 100. INLAY RETAINED FIXED PARTIAL DENTURES A special category of conservative dental restorations are the posterior teeth 3-unit inlay retained FPD’s. Of particular interest are those that replace the first molar and are retained on inlay design cavities in the second premolar and second molar, which can be one alternative prosthetic treatment plan of a missing molar or premolar101. It is reported that when preparing an abutment for ceramic crown a 67-73% of the coronal tooth substance is removed102. Therefore more tooth substance is removed on conventional FPD’s than on inlay retained FPD’s104. An alternative technique in which buccal and palatal (lingual) flanges are added in both sides of the inlays seems to improve the prognosis of such special prosthetic construction103. Nevertheless, large amounts of failure of such structures are observed (13% to 37 months)104 and made clinicians cautious to their widespread use, despite the promising strength of such zirconia core constructions in laboratory tests104. MARYLAND FIXED PARTIAL DENTURES Zirconia frameworks have been used for the construction of micromechanical retention FPD’s, which are an alternative approach in several clinical cases where we need a minimally invasive prosthetic rehabilitation. Both single wing and double wing designs were tested. Double wing design appears to have greater resistance to detachment in laboratory tests106. These constructions have as complications detachments107 or fractures of the joints. A new modified surface for bonding gives new prospects for wider use of such special structures108. ZIRCONIA POSTS Castable posts of noble metals are considered as the reference method in restoring endodontically treated teeth with extensive loss of dental hard substances109. The Hellenic Stomatological Review 57: 101-137, 2013 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review EÈÎ. 6: EÍ·ÈÚÂÙÈο ÌÂÁ¿ÏÔ˘ ÌÂÁ¤ıÔ˘˜ Û‡Ó‰ÂÛÌÔÈ(>4x4mm) Û ÛÎÂÏÂÙfi Á¤Ê˘Ú·˜ ˙ÈÚÎÔÓ›·˜ ÙÂÛÛ¿ÚˆÓ ÙÂÌ·¯›ˆÓ need for more aesthetic posts was driven from the fact that the color of a ceramic crown is affected by the color of the underlying coronal build-up, leading to the search for more esthetic materials110, 111. The use of zirconia as a structural material for posts began in 1993 as an alternative solution and was subsequently extended. The type of restoration on an endodontically treated tooth when a post method is selected depends on several factors. Today the choices are divided into cast posts and a wide range of prefabricated ones. In the second case, the restoration of the removed tooth substance in the coronal part is made with a restoring material. Following this classification manufacturers have released systems of prefabricated or customized zirconia posts111. According to some authors fiberglass posts have lower probability of root fracture than zirconia posts. The latter are not removed when a failure occurs. Toksavul found similar strengths in three different post systems and concluded that zirconia posts are reliable as aesthetic posts in cases when all-ceramic crowns are used to restore endodontically treated teeth111. However, regardless of type and technique, zirconia posts have been heavily criticized for the fact that may cause -due to their high rigidity- root fractures more often than fiberglass posts113. There is also an inherent difficulty in bonding zirconia to both adhesive cement and build-up material, but the most important problem is considered the difficulty to remove a zirconia post when endodontic re-treatment is required. It is also almost impossible to grind a cemented zirconia post113, 114. MONOLITHIC ZIRCONIA EÈÎ.7: K¿Ù·ÁÌ· ÛÎÂÏÂÙÔ‡ ˙ÈÚÎÔÓ›·˜ Û Á¤Ê˘Ú· ÙÂÛÛ¿ÚˆÓ ÙÂÌ·¯›ˆÓ (T˙Ô‡Ù˙·˜ I., T˙·Ó·Î¿Î˘ E. 2010) The need to reduce and eliminate chipping failures led to the entrance of a new technique to form full contour restorations with the exclusive use of zirconia material. To differentiate from other materials the term monolithic zirconia is widely used for this new generation materials. The opacity of the material appears to be significantly reduced due to the decrease in the grain size of the material (nm scale). Also due to the high strength of the material very thin restorations can be made(0.6-0.8 mm). These require minimum tooth preparation, almost the same that is needed to construct a full cast crown made of gold, noble or basic alloys. Beyond that, there are some drawbacks and weaknesses of the new material that might impede the wide spreading. First, the aesthetic restorations can be individualized as limited only to external dyes and colors specified by the manufacturer. This of course depends on the patient selection, the skill of the laboratory and the accuracy of color matching. Also the high hardness of the material creates suspicions of the possible abrasion of the enamel antagonist53, 54. OTHER APLLIANCES EÈÎ. 8: H ÚÔËÁÔ‡ÌÂÓË ÂÈÎfiÓ· Û ÏÂÙÔ̤ÚÂÈ· Ì ÙË ¯Ú‹ÛË ÚÔ‚ÔÏ‹˜ ÔÈÛıÔÛΉ·˙fiÌÂÓˆÓ ËÏÂÎÙÚÔÓ›ˆÓ ÛÙËÓ ÂÚÈÔ¯‹ ÙÔ˘ ηٿÁÌ·ÙÔ˜. (BEI 20X) (T˙Ô‡Ù˙·˜ & T˙·Ó·Î¿Î˘ 2010) Hellenic Stomatological Review 57: 101-137, 2013 Ceramic orthodontic brackets were one of the innovations in clinical orthodontics in the late 80s. The first ceramic had low toughness and the material used was alumina114. 121 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review ÊÔÚ¿ ÛÙËÓ ÔÈfiÙËÙ· ÂÊ·ÚÌÔÁ‹˜ ÌÂٷ͇ ÎÏ·ÛÈÎÒÓ ÌÂÙ·ÏÏÔÎÂÚ·ÌÈÎÒÓ Î·Ù·Û΢ÒÓ Î·È Û‡Á¯ÚÔÓˆÓ CAD-CAM ηٷÛ΢ÒÓ ˙ÈÚÎÔÓ›·˜97. EÚÁ·ÛÙËÚȷΤ˜ ÌÂϤÙ˜ ÂÍ·ÎÚ›‚ˆÛ·Ó ÙËÓ ÎÏÈÓÈο ·Ô‰ÂÎÙ‹ ÔÚȷ΋ ÂÊ·ÚÌÔÁ‹ ÁÂÊ˘ÚÒÓ ˙ÈÚÎÔÓ›·˜ ÙÚÈÒÓ Î·È ÙÂÛÛ¿ÚˆÓ ÙÂÌ·¯›ˆÓ ηٷÛ΢·Ṳ̂Ó˜ Ì ۇÁ¯ÚÔÓ· CAD-CAM Û˘ÛÙ‹Ì·Ù·98 ,99, 100. °EºYPE™ ™THPIZOMENE™ ™E EN£ETA/INLAY RETAINED FPDS M›· ȉȷ›ÙÂÚË Î·ÙËÁÔÚ›· Û˘ÓÙËÚËÙÈÎÒÓ ÚÔÛıÂÙÈÎÒÓ ·ÔηٷÛÙ¿ÛÂˆÓ ·ÔÙÂÏÔ‡Ó ÔÈ ÙÚÈÒÓ ÙÂÌ·¯›ˆÓ Á¤Ê˘Ú˜ ÔÈÛı›ˆÓ ‰ÔÓÙÈÒÓ ÛÙËÚÈ˙fiÌÂÓ˜ Û ¤ÓıÂÙ·. I‰È·›ÙÂÚÔ ÂӉȷʤÚÔÓ ·ÔÙÂÏÔ‡Ó ÂΛӘ Ô˘ ·ÓÙÈηıÈÛÙÔ‡Ó ÙÔÓ ÚÒÙÔ ÁÔÌÊ›Ô Î·È ÛÙËÚ›˙ÔÓÙ·È Û ÎÔÈÏfiÙËÙ˜ ÂÓı¤ÙˆÓ ÛÙÔÓ ‰Â‡ÙÂÚÔ ÚÔÁfiÌÊÈÔ Î·È ÁÔÌÊ›Ô ·ÓÙ›ÛÙÔȯ·, ÔÈ Ôԛ˜ ÌÔÚÔ‡Ó Ó· ·ÔÙÂϤÛÔ˘Ó ¤Ó· ·fi ÂÓ·ÏÏ·ÎÙÈο Û¯¤‰È· ıÂڷ›·˜ ·ÔηٿÛÙ·Û˘ ÂÓfi˜ ÂÏÏ›ÔÓÙÔ˜ ÁÔÌÊ›Ô˘ ‹ ÚÔÁÔÌÊ›Ô˘101. AӷʤÚÂÙ·È fiÙÈ Î·Ù¿ ÙËÓ ·Ú·Û΢‹ ÂÓfi˜ ÛÙËÚ›ÁÌ·ÙÔ˜ ÁÈ· ÔÏÔÎÂÚ·ÌÈ΋ ÛÙÂÊ¿ÓË ·Ê·ÈÚÂ›Ù·È ÙÔ 67-73% Ù˘ Ô‰ÔÓÙÈ΋˜ Ô˘Û›·˜ Ù˘ ̇Ï˘102. ™˘ÓÂÒ˜ ÂÚÈÛÛfiÙÂÚË Ô‰ÔÓÙÈ΋ Ô˘Û›· ·Ê·ÈÚÂ›Ù·È Û ‰fiÓÙÈ·-ÛÙËÚ›ÁÌ·Ù· Ì ‰‡Ô ÂÍˆÌ˘ÏÈΤ˜ ·Ú·Û΢¤˜ ÔÏÈ΋˜ Î¿Ï˘„˘ ·Ú¿ Û ÌÈ· Á¤Ê˘Ú· ÛÙËÚÈ˙fiÌÂÓË Û ¤ÓıÂÙ·104. M›· ÂÓ·ÏÏ·ÎÙÈ΋ Ù¯ÓÈ΋ ηٿ ÙËÓ ÔÔ›· ÚÔÛÙ›ıÂÓÙ·È ÙÂÚ‡ÁÈ· ·ÚÂȷο Î·È ˘ÂÚÒÈ· (ÁψÛÛÈο) Âη٤ڈıÂÓ ÙˆÓ ÂÓı¤ÙˆÓ-ÛÙËÚÈÁÌ¿ÙˆÓ Ê·›ÓÂÙ·È Ó· ‚ÂÏÙÈÒÓÂÈ ÙËÓ ÚfiÁÓˆÛË Ù¤ÙÔÈˆÓ ÂȉÈÎÒÓ ÚÔÛıÂÙÈÎÒÓ Î·Ù·Û΢ÒÓ103. ¶·ÚfiÏ· ·˘Ù¿, Ù· ÌÂÁ¿Ï· ÔÛÔÛÙ¿ ·ÔÙ˘¯›·˜ Ù¤ÙÔÈˆÓ Î·Ù·Û΢ÒÓ (13% Û 37 Ì‹Ó˜)105 Ì·˜ ηıÈÛÙÔ‡Ó ÂÈÊ˘Ï·ÎÙÈÎÔ‡˜ ÛÙËÓ Â˘Ú›· ¯Ú‹ÛË ÙÔ˘˜, ·Ú¿ ÙËÓ ÔÏÏ¿ ˘ÔÛ¯fiÌÂÓË ˘„ËÏ‹ ·ÓÙÔ¯‹ ÙÔ˘ ÛÎÂÏÂÙÔ‡ ˙ÈÚÎÔÓ›·˜ Û ÂÚÁ·ÛÙËÚȷΤ˜ ‰ÔÎÈ̷ۛ˜ Ù¤ÙÔÈˆÓ Î·Ù·Û΢ÒÓ104. °EºYPE™ TY¶OY MARYLAND OÈ ÛÎÂÏÂÙÔ› ˙ÈÚÎÔÓ›·˜ ¤¯Ô˘Ó ¯ÚËÛÈÌÔÔÈËı› ÁÈ· ÙËÓ Î·Ù·Û΢‹ ÁÂÊ˘ÚÒÓ ÌÈÎÚÔÌ˯·ÓÈ΋˜ Û˘ÁÎÚ¿ÙËÛ˘, ÔÈ Ôԛ˜ ·ÔÙÂÏÔ‡Ó ÌÈ· ÂÓ·ÏÏ·ÎÙÈ΋ ÚÔÛ¤ÁÁÈÛË Û ·ÚÎÂÙ¤˜ ÎÏÈÓÈΤ˜ ÂÚÈÙÒÛÂȘ Ô˘ ¯ÚÂÈ¿˙ÂÙ·È ÌÈ· ÂÏ¿¯ÈÛÙ· ·ÚÂÌ‚·ÙÈ΋ ÚÔÛıÂÙÈ΋ ·ÔηٿÛÙ·ÛË. Œ¯Ô˘Ó ‰ÔÎÈÌ·ÛÙ› ÙfiÛÔ ÌÔÓÔÙ¤Ú˘ÁÔÈ fiÛÔ Î·È ‰ÈÙ¤Ú˘ÁÔÈ Û¯Â‰È·ÛÌÔ›, ÂÎ ÙˆÓ ÔÔ›ˆÓ ÔÈ ‰ÈÙ¤Ú˘ÁÔÈ Ê·›ÓÂÙ·È Ó· ¤¯Ô˘Ó ÌÂÁ·Ï‡ÙÂÚË ·ÓÙÔ¯‹ ÛÙËÓ ·ÔÎfiÏÏËÛË ÂÚÁ·ÛÙËÚȷο106. OÈ Î·Ù·Û΢¤˜ ·˘Ù¤˜ ¤¯Ô˘Ó ˆ˜ Û˘Ó‹ıÂȘ ÂÈÏÔΤ˜ ÙȘ ·ÔÎÔÏÏ‹ÛÂȘ107 ‹ Ù· ηٿÁÌ·Ù· ÙˆÓ Û˘Ó‰¤Û̈Ó. MÈ· Ó¤· ÙÚÔÔÔÈË̤ÓË ÂÈÊ¿ÓÂÈ· ÁÈ· Û˘ÁÎfiÏÏËÛË ‰›ÓÂÈ Ó¤Â˜ ÚÔÔÙÈΤ˜ ÁÈ· ¢ڇÙÂÚË ¯Ú‹ÛË Ù¤ÙÔÈˆÓ ÂȉÈÎÒÓ Î·Ù·Û΢ÒÓ108. A•ONE™ EN¢OPPIZIKOI OÈ ¯˘ÙÔ› ÂÓ‰ÔÚÚÈ˙ÈÎÔ› ¿ÍÔÓ˜ ·fi ¢ÁÂÓ‹ ̤ٷÏÏ· ıˆÚÔ‡ÓÙ·È ˆ˜ ̤ıÔ‰Ô˜ ·Ó·ÊÔÚ¿˜ ÛÙËÓ ·ÔηٿÛÙ·ÛË ÂÓ‰Ô‰ÔÓÙÈο ıÂÚ·Â˘Ì¤ÓˆÓ ‰ÔÓÙÈÒÓ Ì ÂÎÙÂٷ̤ÓË ·ÒÏÂÈ· ÛÎÏËÚÒÓ Ô‰ÔÓÙÈÎÒÓ Ô˘ÛÈÒÓ109. H ·Ó¿ÁÎË ÁÈ· ¿ÍÔÓ˜ Ì ηχÙÂÚË ·ÈÛıËÙÈ΋ ·fi‰ÔÛË Û ÂÚÈÙÒÛÂȘ fiÔ˘ Ë ¯ÚˆÌ·ÙÈ΋ ÈÛÙfiÙËÙ· ÌÈ·˜ ÔÏÔÎÂÚ·ÌÈ΋˜ ÛÙÂÊ¿Ó˘ ÂËÚ¿˙ÂÙ·È ·fi ÙÔ ¯ÚÒÌ· Ù˘ ˘ÔΛÌÂÓ˘ Ì˘ÏÈ΋˜ ·Ó·Û‡122 Then zirconia115 was used as an alternative ceramic with some disadvantages. The intense white color was not particularly aesthetic and high opacity inhibits photopolymerization of the adhesive substrate114. On the other hand, zirconia brackets exhibited excellent resistance to abrasion116, greater resistance to deformation and less retention of dental plaque74. In direct comparison with the metal brackets show reduced efficacy of tooth movement, greater wear of enamel due to frequent detachment74 and greater wear of the opposite dental barrier117. Zirconia brackets are however, an alternative solution115. Other structures of zirconia for dental use that have been released are some types of precision attachments for which so far there is no available literature on their efficacy and clinical performance74. A number of new cutters and surgical instruments based on zirconia have been also released74. IMPLANT ABUTMENTS Almost in all implant brands on the market, there is a number of prefabricated and customized abutments for implant restorations, made of titanium alloys, gold or nonprecious metals and ceramic materials118. First ceramic abutments were made of alumina and came into production in 1993, which despite their excellent aesthetic performance were criticized for certain failures (abutment fractures)119, 120. Then in order to reduce the risk of failure zirconia abutments were tested122. Zirconia abutments can be prefabricated or customized. The selection of prefabricated is reliable and practical, but customized ones with the help of CAD-CAM technology can be designed for optimum aesthetics and integration of soft tissues74. There is need for more randomized clinical trials to evaluate the benefits of using zirconia abutments. In general having only a few research data, findings may be summarized as follows121: a) In frontal areas zirconia abutments function without complications (four years studies), without knowing their reliability for posterior restorations. b) The biocompatibility of zirconia is similar to that of titanium at periimplant soft tissues and the accumulation of dental plaque is less than that of titanium. In a clinical study after four years there was no abutment fracture, but only loosening of abutment screw in a small percentage and ceramic chipping123. Other advantages are considered the radiolucency of the abutments which is similar to metals and allows a reliable assessment of the fit accuracy through a radiographic imaging12, the less discoloration of tissues in relation to basic alloys and even the less bacterial adhesion to the surface of zirconia124. COMPLICATIONS OF ZIRCONIA RESTORATIONS 1. CERAMIC CHIPPING Complication rates of zirconia FPD’s survival, show that Hellenic Stomatological Review 57: 101-137, 2013 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review ÛÙ·Û˘ Ô‰‹ÁËÛ ÛÙËÓ ·Ó·˙‹ÙËÛË ˘ÏÈÎÒÓ Ô˘ ·¤‰È‰·Ó ηχÙÂÚË ·ÈÛıËÙÈ΋110, 111. H ¯Ú‹ÛË Ù˘ ˙ÈÚÎÔÓ›·˜ ˆ˜ ˘ÏÈÎÔ‡ ηٷÛ΢‹˜ ÂÓ‰ÔÚÚÈ˙ÈÎÒÓ ·ÍfiÓˆÓ ÍÂΛÓËÛ ÙÔ 1993 ˆ˜ ÂÓ·ÏÏ·ÎÙÈ΋ χÛË Î·È ÂÂÎÙ¿ıËΠÛÙË Û˘Ó¤¯ÂÈ·. H ÂÈÏÔÁ‹ ÙÔ˘ ›‰Ô˘˜ Ù˘ ·ÔηٿÛÙ·Û˘ ÂÓfi˜ ÂÓ‰Ô‰ÔÓÙÈο ıÂÚ·Â˘Ì¤ÓÔ˘ ‰ÔÓÙÈÔ‡ fiÙ·Ó ÂÈÏÂÁ› Ó· ÙÔÔıÂÙËı› ÂÓ‰ÔÚÚÈ˙ÈÎfi˜ ¿ÍÔÓ·˜ ÂÍ·ÚÙ¿Ù·È ·fi ·ÚÎÂÙÔ‡˜ ·Ú¿ÁÔÓÙ˜. ™‹ÌÂÚ· ÔÈ ÂÈÏÔÁ¤˜ ¯ˆÚ›˙ÔÓÙ·È Û ¯˘ÙÔ‡˜ ÂÍ·ÙÔÌÈÎÂ˘Ì¤ÓÔ˘˜ ¿ÍÔÓ˜ Î·È Û ¤Ó· ÌÂÁ¿ÏÔ Ê¿ÛÌ· ÚÔηٷÛ΢·ÛÌ¤ÓˆÓ ÂÓ‰ÔÚÚÈ˙ÈÎÒÓ ·ÍfiÓˆÓ. ™ÙÔ˘˜ ‰Â‡ÙÂÚÔ˘˜, Ë ·ÔηٿÛÙ·ÛË Ù˘ ·Ê·ÈÚÂı›۷˜ Ô‰ÔÓÙÈ΋˜ Ô˘Û›·˜ ÛÙÔ Ì˘ÏÈÎfi ̤ÚÔ˜ Á›ÓÂÙ·È Ì ¤Ó· ˘ÏÈÎfi ·Ó·Û‡ÛÙ·Û˘. AÎÔÏÔ˘ıÒÓÙ·˜ ·˘Ù‹ ÙËÓ Ù·ÍÈÓfiÌËÛË Î·Ù¿ ·ÚfiÌÔÈÔ ÙÚfiÔ ¤¯Ô˘Ó ΢ÎÏÔÊÔÚ‹ÛÂÈ Û˘ÛÙ‹Ì·Ù· ÚÔηٷÛ΢·Ṳ̂ӈÓ, ·ÏÏ¿ Î·È ÂÍ·ÙÔÌÈÎÂ˘Ì¤ÓˆÓ ÂÓ‰ÔÚÚÈ˙ÈÎÒÓ ·ÍfiÓˆÓ ˙ÈÚÎÔÓ›·˜111. ™‡Ìʈӷ Ì ÔÚÈṲ̂ÓÔ˘˜ Û˘ÁÁÚ·Ê›˜ ÔÈ ¿ÍÔÓ˜ ˘·ÏÔÓËÌ¿ÙˆÓ ¤¯Ô˘Ó ÌÈÎÚfiÙÂÚË Èı·ÓfiÙËÙ· ηٷÛÙÚÔÊÈÎÒÓ Î·Ù·ÁÌ¿ÙˆÓ Û ۯ¤ÛË Ì ÙÔ˘˜ ¿ÍÔÓ˜ ˙ÈÚÎÔÓ›·˜, Î·È ÔÈ ÙÂÏÂ˘Ù·›ÔÈ ‰ÂÓ ·Ê·ÈÚÔ‡ÓÙ·È fiÙ·Ó Û˘Ì‚Â› ·ÔÙ˘¯›·. O Toksavul112 ‚ڋΠ·ÚfiÌÔȘ ·ÓÙÔ¯¤˜ Û 3 ‰È·ÊÔÚÂÙÈο ›‰Ë ·ÍfiÓˆÓ Î·È Î·Ù¤ÏËÍ fiÙÈ ÔÈ ¿ÍÔÓ˜ ˙ÈÚÎÔÓ›·˜ Â›Ó·È ·ÍÈfiÈÛÙÔÈ ˆ˜ ÚÔ˜ ÙÔ ·ÈÛıËÙÈÎfi ·ÔÙ¤ÏÂÛÌ· Û ÂÚÈÙÒÛÂȘ ÔÏÔÎÂÚ·ÌÈÎÒÓ ÛÙÂÊ·ÓÒÓ Ô˘ ηχÙÔ˘Ó ÂÓ‰Ô‰ÔÓÙÈο ıÂÚ·Â˘Ì¤Ó· ‰fiÓÙÈ· Ì ÂÍ·ÈÚÂÙÈ΋ ηٷÛÙÚÔÊ‹ ̇Ï˘111. °ÂÓÈο ¿ÓÙˆ˜, ·ÓÂÍ·Úًو˜ Ù‡Ô˘ Î·È Ù¯ÓÈ΋˜, ÔÈ ¿ÍÔÓ˜ ˙ÈÚÎÔÓ›·˜ ¤¯Ô˘Ó ˘ÔÛÙ› ¤ÓÙÔÓË ÎÚÈÙÈ΋ ÁÈ· ÙÔ ÁÂÁÔÓfi˜ fiÙÈ Ê·›ÓÂÙ·È Ó· ÚÔηÏÔ‡Ó ÂÍ·ÈÙ›·˜ Ù˘ ÌÂÁ¿Ï˘ ·Î·Ì„›·˜ ÙÔ˘˜ Û˘¯Ó¿ ηٿÁÌ·Ù· ÚÈ˙ÒÓ ÈÔ Û˘¯Ó¿ ·fi ÙÔ˘˜ ¿ÍÔÓ˜ ˘·ÏÔÓËÌ¿ÙˆÓ113. Y¿Ú¯ÂÈ Â›Û˘ ÌÈ· ÂÁÁÂÓ‹˜ ‰˘ÛÎÔÏ›· Û˘ÁÎfiÏÏËÛ˘ Ù˘ ˙ÈÚÎÔÓ›·˜ ÙfiÛÔ Ì ÙËÓ Û˘ÁÎÔÏÏËÙÈ΋ ÎÔÓ›· fiÛÔ Î·È Ì ÙÔ ˘ÏÈÎfi ·Ó·Û‡ÛÙ·Û˘, ·ÏÏ¿ ÙÔ Ï¤ÔÓ ÛËÌ·ÓÙÈÎfi Úfi‚ÏËÌ· ıˆÚÂ›Ù·È Ë ‰‡ÛÎÔÏË ·Ê·›ÚÂÛË ÙÔ˘ ¿ÍÔÓ· ˙ÈÚÎÔÓ›·˜ Û ÂÚ›ÙˆÛË Ô˘ ¯ÚÂÈ¿˙ÂÙ·È Â·Ó¿ÏË„Ë Ù˘ ÂÓ‰Ô‰ÔÓÙÈ΋˜ ıÂڷ›·˜ ηıÒ˜ Â›Ó·È ·‰‡Ó·ÙÔ Ó· ÙÚÔ¯ÈÛÙ› ¤Ó·˜ Û˘ÁÎÔÏÏË̤ÓÔ˜ ¿ÍÔÓ·˜113, 114. MONO§I£IKH ZIPKONIA H ·Ó¿ÁÎË ÁÈ· ÙË Ì›ˆÛË Î·È ÂÍ¿ÏÂÈ„Ë ÙˆÓ ·ÛÙÔ¯ÈÒÓ Ù˘ ÂÈÎ·Ï˘ÙÈ΋˜ ÔÚÛÂÏ¿Ó˘ ÛÙȘ ηٷÛ΢¤˜ ˙ÈÚÎÔÓ›·˜ Ô‰‹ÁËÛ ÛÙËÓ Â›ÛÔ‰Ô ÌÈ·˜ Ó¤·˜ Ù¯ÓÈ΋˜ ‰È·ÌfiÚʈÛ˘ ·Î›ÓËÙˆÓ ·ÔηٷÛÙ¿ÛÂˆÓ Ï‹ÚÔ˘˜ Ô‰ÔÓÙÈ΋˜ ·Ó·ÙÔÌ›·˜ Ì ·ÔÎÏÂÈÛÙÈ΋ ¯Ú‹ÛË ˘ÏÈÎÔ‡ ˙ÈÚÎÔÓ›·˜53. °È· ÙË ‰È·ÊÔÚÔÔ›ËÛË ·fi Ù· ¿ÏÏ· ˘ÏÈο ˙ÈÚÎÔÓ›·˜ ·Ô‰fiıËÎÂ Ô ¯·Ú·ÎÙËÚÈÛÌfi˜ ÌÔÓÔÏÈıÈ΋ ˙ÈÚÎÔÓ›· ÁÈ· ·˘Ù‹ ÙË Ó¤· ÁÂÓÈ¿ ˘ÏÈÎÒÓ. H ·‰È·Ê¿ÓÂÈ· ÙÔ˘ ˘ÏÈÎÔ‡ Ê·›ÓÂÙ·È Ó· ÌÂÈÒÓÂÙ·È ·ÈÛıËÙ¿ ÏfiÁˆ Ù˘ Ì›ˆÛ˘ ÙÔ˘ ÌÂÁ¤ıÔ˘˜ ÙˆÓ ÎfiÎÎˆÓ ÙÔ˘ ˘ÏÈÎÔ‡ (Ù˘ Ù¿Í˘ ÙˆÓ nm)54. E›Û˘ ÏfiÁˆ Ù˘ ÌÂÁ¿Ï˘ ·ÓÙÔ¯‹˜ ÙÔ˘ ˘ÏÈÎÔ‡ ηٷÛ΢¿˙ÔÓÙ·È Ôχ ÏÂÙ¿ ¿¯Ë ·ÔηٷÛÙ¿ÛÂˆÓ 0,6-0,8¯ÈÏ. Ô˘ ··ÈÙÔ‡Ó ÂÏ¿¯ÈÛÙË Ô‰ÔÓÙÈ΋ ·Ú·Û΢‹ fiÛË ÂÚ›Ô˘ ··ÈÙ›ÙÔ ÁÈ· ÙËÓ Î·Ù·Û΢‹ ÌÈ·˜ ÔÏÈ΋˜ ¯˘Ù‹˜ ÛÙÂÊ¿Ó˘ ·fi ÎÚ¿Ì·Ù· ¯Ú˘ÛÔ‡, ¢ÁÂÓÒÓ ‹ ‚·ÛÈÎÒÓ ÎÚ·Ì¿ÙˆÓ. Afi ÂΛ Î·È ¤Ú· ˘¿Ú¯Ô˘Ó ÔÚÈṲ̂ӷ ÌÂÈÔÓÂÎÙ‹Ì·Ù· Î·È ·‰˘Ó·Ì›Â˜ ÙÔ˘ Ó¤Ô˘ ˘ÏÈÎÔ‡ Ô˘ Èı·Ófi Ó· ÂÌÔ‰›ÛÔ˘Ó ÙËÓ Â˘Ú›· ÂͿψۋ ÙÔ˘. K·Ù·Ú¯‹Ó Ë ·ÈÛıËÙÈ΋ ÙˆÓ ·ÔηٷÛÙ¿ÛÂˆÓ ‰ÂÓ ÌÔÚ› Ó· ÂÍ·ÙÔÌÈ΢ٛ ηıÒ˜ ÂÚÈÔÚ›˙ÂÙ·È Û Â͈ÙÂÚÈΤ˜ ÌfiÓÔ ¯ÚˆÛÙÈΤ˜ Î·È ÛÙ· ¯ÚÒHellenic Stomatological Review 57: 101-137, 2013 the most frequent technical complication is the loss of the ceramic veneering layer (chipping)66, 125. There are many factors, such as the proper design of the zirconia framework to support the porcelain veneering layer, the appropriate processing in the dental laboratory, and further improvements in mechanical properties and application techniques of porcelain veneering that affect chipping rates125. Each manufacturer recommends treating the surface of the zirconia framework (eg sandblast and heat treatments) before veneering with porcelain. However, the effect of surface treatments on the bonding strength of porcelain to zirconia is still controversial. There are differences in thermal expansion coefficients and firing temperatures between commercial veneering ceramics for zirconia. This implies that different products have different powder compositions. Compatibility of the coefficients of thermal expansion needs improvement, which will likely include the optimization of powder synthesis126. However, there is no clear evidence demonstrating the presence of chemical bonds between zirconia and ceramic veneer, although there is one report126 that suggests the existence of such bond. Therefore it is assumed that micromechanical adhesion plays a major role in integrating zirconia and porcelain. 2. CONNECTOR FRACTURE Another serious complication that leads to failure restorations is the fracture of the frame. Most often is observed to the connectors. The first few failures led to the introduction of stricter criteria for the minimum dimensions of frame and connectors and the use of shorter span restorations5 (Fig. 6). Of particular importance is the design of the connectors where sharp endings can lead inevitably to stress concentration points and failure. (Fig. 7-8) 3. RESTORATION DEBONDING/DECEMENTATION The loss of retention (adhesive cement fracture) of one tooth abutment or the entirely decementation of a dental prosthesis is an important technical complication that affects its survival. It is of course possible to re-cement the prosthesis without any other complication, but sometimes other biological complications such as secondary caries or loss of pulp vitality require immediate replacement of the prosthesis. The loss of retention is a very low complication rate in single crowns or FPDs127. Nevertheless, the investigation and understanding of the causes leading to decementation of prostheses can lead to more reliable restorations. Cementation is the last clinical step for the construction of a prosthetic restoration. Provided that the preceding steps have been executed perfectly, final cementation completes a reliable prosthetic restoration. The bonding surfaces must produce the maximum quality of bond so that there is a long-term prosthetic survival and the possibility of microleakage is minimized. Apart from the surface of the dental abutment, the inner surface of the prosthesis 123 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review Ì·Ù· Ô˘ ηıÔÚ›˙ÔÓÙ·È ·fi ÙÔÓ Î·Ù·Û΢·ÛÙ‹. A˘Ùfi ‚¤‚·È· ÂÍ·ÚÙ¿Ù·È ·fi ÙËÓ ÂÈÏÔÁ‹ ÂÚÈÛÙ·ÙÈÎÔ‡, ÙËÓ ÂȉÂÍÈfiÙËÙ· ÙÔ˘ ÂÚÁ·ÛÙËÚ›Ô˘ Î·È ÙËÓ ·ÎÚ›‚ÂÈ· Ù˘ ¯ÚˆÌ·ÙÔÏË„›·˜. AÎfiÌË Ë ÌÂÁ¿ÏË ÛÎÏËÚfiÙËÙ· ÙÔ˘ ˘ÏÈÎÔ‡ ‰ËÌÈÔ˘ÚÁ› ˘Ô„›Â˜ ÁÈ· Èı·Ó‹ ·ÔÙÚÈ‚‹ Ù˘ ·‰·Ì·ÓÙ›Ó˘ ÙÔ˘ ·ÓÙ·ÁˆÓÈÛÙ‹. A§§E™ KATA™KEYE™/OP£O¢ONTIKH T· ÎÂÚ·ÌÈο ÔÚıÔ‰ÔÓÙÈο ·Á·ÏÈ· (brackets) ·ÔÙ¤ÏÂÛ·Ó ÌÈ· ·fi ÙȘ ηÈÓÔÙƠ̂˜ ÛÙËÓ ÎÏÈÓÈ΋ ÔÚıÔ‰ÔÓÙÈ΋ ÛÙ· Ù¤ÏË Ù˘ ‰ÂηÂÙ›·˜ ÙÔ˘ ’80. T· ÚÒÙ· ÎÂÚ·ÌÈο ›¯·Ó ¯·ÌËÏ‹ ‰˘ÛıÚ·˘ÛÙfiÙËÙ· Î·È ÙÔ ˘ÏÈÎfi Ô˘ ¯ÚËÛÈÌÔÔÈ‹ıËΠ‹Ù·Ó Ë ·ÏÔ˘Ì›Ó·115. ™ÙË Û˘Ó¤¯ÂÈ· Ë ˙ÈÚÎÔÓ›·116 ¯ÚËÛÈÌÔÔÈ‹ıËΠˆ˜ ÂÓ·ÏÏ·ÎÙÈÎfi ÎÂÚ·ÌÈÎfi Ì ·ÚÎÂÙ¿ fï˜ ÌÂÈÔÓÂÎÙ‹Ì·Ù·. TÔ ¤ÓÙÔÓ· Ï¢Îfi ¯ÚÒÌ· ‰ÂÓ ‹Ù·Ó ȉȷ›ÙÂÚ· ·ÈÛıËÙÈÎfi Î·È Ë ˘„ËÏ‹ ·‰È·Ê¿ÓÂÈ· ÂÌfi‰È˙ ÙÔÓ ÊˆÙÔÔÏ˘ÌÂÚÈÛÌfi ÙÔ˘ Û˘ÁÎÔÏÏËÙÈÎÔ‡ ˘ÔÛÙÚÒÌ·ÙÔ˜115. Afi ÙËÓ ¿ÏÏË ÏÂ˘Ú¿ ÂÌÊ¿ÓÈ˙ ÂÍ·ÈÚÂÙÈ΋ ·ÓÙ›ÛÙ·ÛË ÛÙËÓ ·ÔÙÚÈ‚‹116, ÌÂÁ·Ï‡ÙÂÚË ·ÓÙÔ¯‹ ÛÙËÓ ·Ú·ÌfiÚʈÛË Î·È ÏÈÁfiÙÂÚË Û˘ÁÎÚ¿ÙËÛË Ô‰ÔÓÙÈ΋˜ ÌÈÎÚԂȷ΋˜ Ͽη˜75. ™Â ¿ÌÂÛË Û‡ÁÎÚÈÛË Ì ٷ ÌÂÙ·ÏÏÈο brackets ·ÚÔ˘ÛÈ¿˙Ô˘Ó ÌÂȈ̤ÓË ·ÔÙÂÏÂÛÌ·ÙÈÎfiÙËÙ· ÌÂٷΛÓËÛ˘ ‰ÔÓÙÈÒÓ, ÌÂÁ·Ï‡ÙÂÚË ÊıÔÚ¿ Ù˘ ·‰·Ì·ÓÙ›Ó˘ ÏfiÁˆ ÙˆÓ Û˘¯ÓÒÓ ·ÔÎÔÏÏ‹ÛˆÓ75 Î·È ÌÂÁ·Ï‡ÙÂÚË ·ÔÙÚÈ‚‹ ÙÔ˘ ·ÓÙ›ıÂÙÔ˘ Ô‰ÔÓÙÈÎÔ‡ ÊÚ·ÁÌÔ‡117. AÔÙÂÏÔ‡Ó ¿ÓÙˆ˜ ÌÈ· ÂÓ·ÏÏ·ÎÙÈ΋ χÛË ÛÙËÓ ÔÚıÔ‰ÔÓÙÈ΋115. ÕÏϘ ηٷÛ΢¤˜ ˙ÈÚÎÔÓ›·˜ ÁÈ· Ô‰ÔÓÙÈ·ÙÚÈ΋ ¯Ú‹ÛË Ô˘ ¤¯Ô˘Ó ΢ÎÏÔÊÔÚ‹ÛÂÈ Â›Ó·È ÔÚÈṲ̂ÓÔÈ Ù‡ÔÈ Û˘Ó‰¤ÛÌˆÓ ·ÎÚȂ›·˜ ÁÈ· ÙÔ˘˜ ÔÔ›Ô˘˜ ˆ˜ ÙÒÚ· ‰ÂÓ ˘¿Ú¯ÂÈ ‰È·ı¤ÛÈÌË ‚È‚ÏÈÔÁÚ·Ê›· ÁÈ· ÙËÓ ·ÔÙÂÏÂÛÌ·ÙÈÎfiÙËÙ· Î·È ÙËÓ ÎÏÈÓÈ΋ ÙÔ˘˜ ·fi‰ÔÛË. E›Û˘ ¤¯ÂÈ Î·Ù·Û΢·ÛÙ› ÛÂÈÚ¿ Ó¤ˆÓ ÎÔÙÈÎÒÓ Î·È ¯ÂÈÚÔ˘ÚÁÈÎÒÓ ÂÚÁ·Ï›ˆÓ Ì ‚¿ÛË ÙË ˙ÈÚÎÔÓ›·75. most often needs some form of treatment to strengthen the cement-substrate bond. The specificity of zirconia framework restorations lies in the fact that due to its high hardness and crystallinity, it remains almost unaffected by any processing128. There have been several experimental attempts to improve the bond between zirconia and various cements with different results. There is still a wide field of research until the introduction of a protocol for cementing zirconia restorations that may eliminate the unpleasant complication of restoration decementation. CLINICAL CASES 1) Zirconia crown replacing an old metal-ceramic crown on # 11# (Fig. 9-12) 2) Monolithic zirconia restorations (Fig.13 a-d and Fig.14 a-d). Fig. 9a: Image of cracked metal-ceramic crown in #21 ¢IAB§ENNO°ONIA ™THPI°MATA EMºYTEYMATøN ™Â οı ÔÏÔÎÏËڈ̤ÓÔ Û‡ÛÙËÌ· ÚÔÛıÂÙÈ΋˜ ·ÔηٿÛÙ·Û˘ ÂÌÊ˘ÙÂ˘Ì¿ÙˆÓ Û¯Â‰fiÓ fiÏˆÓ fiÛˆÓ Î˘ÎÏÔÊÔÚÔ‡Ó ÛÙËÓ ·ÁÔÚ¿, ˘¿Ú¯ÂÈ ÌÈ· ÛÂÈÚ¿ ÚÔηٷÛ΢·ÛÌ¤ÓˆÓ Î·È ÂÍ·ÙÔÌÈÎÂ˘Ì¤ÓˆÓ ÛÙËÚÈÁÌ¿ÙˆÓ ÁÈ· ÂÈÂÌÊ˘ÙÂ˘Ì·ÙÈΤ˜ ·ÔηٷÛÙ¿ÛÂȘ, ηٷÛ΢·ÛÌ¤ÓˆÓ ·fi ÎÚ¿Ì·Ù· ÙÈÙ·Ó›Ô˘, ¯Ú˘ÛÔ‡ ‹ ÌË Â˘ÁÂÓÒÓ ÌÂÙ¿ÏÏˆÓ Î·È ÎÂÚ·ÌÈÎÒÓ ˘ÏÈÎÒÓ118. T· ÚÒÙ· ÎÂÚ·ÌÈο ÛÙËÚ›ÁÌ·Ù· ·fi ·ÏÔ˘Ì›Ó· ÂÌÊ·Ó›ÛÙËÎ·Ó ÛÙËÓ ·Ú·ÁˆÁ‹ ÙÔ 1993, Ù· ÔÔ›· fï˜ ·Ú¿ ÙËÓ ÂÍ·ÈÚÂÙÈ΋ ·ÈÛıËÙÈ΋ ÙÔ˘˜ ·fi‰ÔÛË ‰¤¯ÙËÎ·Ó ÎÚÈÙÈ΋ ÁÈ· ÔÚÈṲ̂Ó˜ ·ÔÙ˘¯›Â˜ (ηٿÁÌ·Ù· ÎÔÏÔ‚ˆÌ¿ÙˆÓ)119, 120. ™ÙË Û˘Ó¤¯ÂÈ· ÚÔÎÂÈ̤ÓÔ˘ Ó· ÌÂȈı› Ô Î›Ó‰˘ÓÔ˜ ıÚ·‡ÛÂˆÓ ‰ÔÎÈÌ¿ÛÙËÎ·Ó ÛÙËÚ›ÁÌ·Ù· ·fi ˙ÈÚÎÔÓ›·122. T· ÛÙËÚ›ÁÌ·Ù· ˙ÈÚÎÔÓ›·˜ ÌÔÚ› Ó· Â›Ó·È ÚÔηٷÛ΢·Ṳ̂ӷ ‹ ÂÍ·ÙÔÌÈÎÂ˘Ì¤Ó·. H ÂÈÏÔÁ‹ ÙˆÓ ÚÔηٷÛ΢·ÛÌ¤ÓˆÓ Â›Ó·È ·ÍÈfiÈÛÙË Î·È Ú·ÎÙÈ΋, ·ÏÏ¿ Ù· ÂÍ·ÙÔÌÈÎÂ˘Ì¤Ó· Ì ÙË ‚Ô‹ıÂÈ· Ù˘ Ù¯ÓÔÏÔÁ›·˜ CAD-CAM ÌÔÚÔ‡Ó Ó· ۯ‰ȷÛÙÔ‡Ó ÁÈ· ȉ·ÓÈ΋ ·ÈÛıËÙÈ΋ Î·È ÂÓۈ̿وÛË ÙˆÓ Ì·Ï·ÎÒÓ ÈÛÙÒÓ75. Y¿Ú¯ÂÈ fï˜ ·Ó¿ÁÎË ÂÚÈÛÛfiÙÂÚˆÓ Ù˘¯·ÈÔÔÈËÌ¤ÓˆÓ ÎÏÈÓÈÎÒÓ ÌÂÏÂÙÒÓ ÁÈ· Ó· ·ÍÈÔÏÔÁËıÔ‡Ó Ù· ÔʤÏË ·fi ÙË ¯Ú‹ÛË ÛÙËÚÈÁÌ¿ÙˆÓ ˙ÈÚÎÔÓ›·˜. ™Â 124 Fig. 9b: Image of cracked metal-ceramic crown in #21(visible metal collar in cervical area) DISCUSSION AND CONCLUSIONS Zirconia - ceramic systems have already gained a significant position in restorative approaches with all-ceramic restorations. The first 3-year and 5-year studies were very encouraging for the behavior of the material in the oral environment, while there is a large research effort to further reduce and eliminate problems encountered in its Hellenic Stomatological Review 57: 101-137, 2013 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review ÁÂÓÈΤ˜ ÁÚ·Ì̤˜ ¤¯ÔÓÙ·˜ Ï›Á· ÂÚ¢ÓËÙÈο ‰Â‰Ô̤ӷ Ù· Û˘ÌÂÚ¿ÛÌ·Ù· ÌÔÚÔ‡Ó Ó· Û˘ÓÔ„ÈÛÙÔ‡Ó ˆ˜ ÂÍ‹˜121: ·) ™Â ÚfiÛıȘ ÂÚÈÔ¯¤˜ Ù· ÛÙËÚ›ÁÌ·Ù· ˙ÈÚÎÔÓ›·˜ ÏÂÈÙÔ˘ÚÁÔ‡Ó ¯ˆÚ›˜ ÂÈÏÔΤ˜ (ÌÂϤÙ˜ ÙÂÛÛ¿ÚˆÓ ÂÙÒÓ), ¯ˆÚ›˜ Ó· ÁÓˆÚ›˙Ô˘Ì ÙËÓ ·ÍÈÔÈÛÙ›· ÙÔ˘˜ ÁÈ· ÙȘ ·ÔηٷÛÙ¿ÛÂȘ ÔÈÛı›ˆÓ ÂÚÈÔ¯ÒÓ ÙÔ˘ ÊÚ·ÁÌÔ‡. ‚) H ‚ÈÔÛ˘Ì‚·ÙfiÙËÙ· Ù˘ ˙ÈÚÎÔÓ›·˜ Â›Ó·È ·Ó¿ÏÔÁË Ì ·˘Ù‹Ó ÙÔ˘ ÙÈÙ·Ó›Ô˘ ÛÙÔ˘˜ ÂÚÈÂÌÊ˘ÙÂ˘Ì·ÙÈÎÔ‡˜ Ì·Ï·ÎÔ‡˜ ÈÛÙÔ‡˜ Î·È Ë Û˘ÁΤÓÙÚˆÛË Ô‰ÔÓÙÈ΋˜ ÌÈÎÚԂȷ΋˜ Ͽη˜ ÌÈÎÚfiÙÂÚË ·fi ·˘Ù‹Ó ÙÔ˘ ÙÈÙ·Ó›Ô˘. ™Â ÎÏÈÓÈ΋ ÌÂϤÙË Â›Û˘ ÙÂÛÛ¿ÚˆÓ ÂÙÒÓ ‰ÂÓ ·Ú·ÙËÚ‹ıËΠοٷÁÌ· ÛÙËÚ›ÁÌ·ÙÔ˜, ·Ú¿ ÌfiÓÔ ·ÔÎÔ¯ÏÈÒÛÂȘ Û ÌÈÎÚfi ÔÛÔÛÙfi ÛÙËÚÈÁÌ¿ÙˆÓ Î·È ·ÔÊÏÔÈÒÛÂȘ ÂÈÎ·Ï˘ÙÈÎÒÓ ÎÂÚ·ÌÈÎÒÓ123. ÕÏÏ· ÏÂÔÓÂÎÙ‹Ì·Ù· ıˆÚÔ‡ÓÙ·È Ë ·ÎÙÈÓԉȷÂÚ·ÙfiÙËÙ· ÙˆÓ ÛÙËÚÈÁÌ¿ÙˆÓ Ô˘ Â›Ó·È ·Ó¿ÏÔÁË ÙˆÓ ÌÂÙ¿ÏÏˆÓ Î·È ÂÈÙÚ¤ÂÈ ·ÍÈfiÈÛÙË ·ÍÈÔÏfiÁËÛË Ù˘ ÂÊ·ÚÌÔÁ‹˜ ̤۷ ·fi ÌÈ· ·ÎÙÈÓÔÁÚ·ÊÈ΋ ·ÂÈÎfiÓÈÛË12, fiˆ˜ ›Û˘ Ô ÌÈÎÚfiÙÂÚÔ˜ ·Ô¯ÚˆÌ·ÙÈÛÌfi˜ ÙˆÓ ÈÛÙÒÓ Û ۯ¤ÛË Ì ٷ ‚·ÛÈο ÎÚ¿Ì·Ù· Î·È ·ÎfiÌË Ë ÌÈÎÚfiÙÂÚË ÚÔÛÎfiÏÏËÛË ‚·ÎÙËÚ›ˆÓ ÛÙËÓ ÂÈÊ¿ÓÂÈ· Ù˘ ˙ÈÚÎÔÓ›·˜124. Fig. 10: Zirconia core try-in E¶I¶§OKE™ A¶OKATA™TA™EøN ME KAPAMIKA ZIPKONIA™ Fig. 11: Final prosthesis 1) A¶Oº§OIø™H KEPAMIKøN E¶IKA§Y¶TIKøN Y§IKøN T· ÔÛÔÛÙ¿ ÂÈÏÔÎÒÓ Î·È ÂÈ‚›ˆÛ˘ ·ÔηٷÛÙ¿ÛÂˆÓ ˙ÈÚÎÔÓ›·˜ Î·È ÌÂÙ·ÏÏÔÎÂÚ·ÌÈ΋˜ ‰Â›¯ÓÔ˘Ó fiÙÈ Ë ÈÔ Û˘¯Ó‹ Ù¯ÓÈ΋ ÂÈÏÔ΋ ÁÈ· ÙȘ ·ÔηٷÛÙ¿ÛÂȘ ˙ÈÚÎÔÓ›·˜ Â›Ó·È Ë ·ÒÏÂÈ· Ù˘ ÂÈÎ·Ï˘ÙÈ΋˜ ÔÚÛÂÏ¿Ó˘ (chipping)66, 125 . Y¿Ú¯Ô˘Ó ÔÏÏÔ› ·Ú¿ÁÔÓÙ˜ Ô˘ ÙËÓ ÂËÚ¿˙Ô˘Ó fiˆ˜ Ô Î·Ù¿ÏÏËÏÔ˜ ۯ‰ȷÛÌfi˜ ÙÔ˘ ÔÏÔÎÂÚ·ÌÈÎÔ‡ ÛÎÂÏÂÙÔ‡ ÁÈ· ÙËÓ ˘ÔÛÙ‹ÚÈÍË Ù˘ ÂÈÎ¿Ï˘„˘ ÔÚÛÂÏ¿Ó˘, ÙÔ ÌÂÁ¿ÏÔ ¿¯Ô˜ Ù˘ ÂÈÎ·Ï˘ÙÈ΋˜ ÔÚÛÂÏ¿Ó˘, Ô Î·Ù¿ÏÏËÏÔ˜ ¯ÂÈÚÈÛÌfi˜ ÛÙÔ Ô‰ÔÓÙÔÙ¯ÓÈÎfi ÂÚÁ·ÛÙ‹ÚÈÔ, Î·È ÔÈ ÂÚ·ÈÙ¤Úˆ ‚ÂÏÙÈÒÛÂȘ ÛÙȘ Ì˯·ÓÈΤ˜ ȉÈfiÙËÙ˜ Î·È ÙȘ Ù¯ÓÈΤ˜ ÂÊ·ÚÌÔÁ‹˜ Ù˘ ÂÈÎ¿Ï˘„˘ ÔÚÛÂÏ¿Ó˘125. K¿ı ηٷÛ΢·ÛÙ‹˜ Û˘ÓÈÛÙ¿ ÂÂÍÂÚÁ·Û›· Ù˘ ÂÈÊ¿ÓÂÈ·˜ ÛÎÂÏÂÙÔ‡ ˙ÈÚÎÔÓ›·˜ (fiˆ˜ ·ÌÌÔ‚ÔÏ‹ Î·È ıÂÚÌÈΤ˜ ÂÂÍÂÚÁ·Û›Â˜) ÚÈÓ ·fi ÙËÓ ÂÈÎ¿Ï˘„Ë Ì ÔÚÛÂÏ¿ÓË. øÛÙfiÛÔ, Ë Â›‰Ú·ÛË ÙˆÓ ıÂÚÌÈÎÒÓ ÂÂÍÂÚÁ·ÛÈÒÓ ÁÈ· ÙËÓ ·‡ÍËÛË ÙÔ˘ ‰ÂÛÌÔ‡ Û‡Ó‰ÂÛ˘ Ù˘ ÔÚÛÂÏ¿Ó˘ Ì ÙË ˙ÈÚÎÔÓ›· Â›Ó·È ·ÎfiÌ· ·ÌÊÈÏÂÁfiÌÂÓË. Y¿Ú¯Ô˘Ó ‰È·ÊÔÚ¤˜ ÛÙÔ˘˜ ıÂÚÌÈÎÔ‡˜ Û˘ÓÙÂÏÂÛÙ¤˜ ‰È·ÛÙÔÏ‹˜ Î·È ıÂÚÌÔÎڷۛ˜ fiÙËÛ˘ ÌÂٷ͇ ÙˆÓ ÂÌÔÚÈο ÚÔ˚fiÓÙˆÓ ÂÈÎ¿Ï˘„˘ ÔÚÛÂÏ¿ÓË ÁÈ· ÙË ˙ÈÚÎÔÓ›·. A˘Ùfi Û˘Ó¿ÁÂÙ·È fiÙÈ Ù· ‰È·ÊÔÚÂÙÈο ÚÔ˚fiÓÙ· ¤¯Ô˘Ó ‰È·ÊÔÚÂÙÈΤ˜ Û˘Óı¤ÛÂȘ ÛÎfiÓ˘. BÂÏÙ›ˆÛË ¯ÚÂÈ¿˙ÂÙ·È ÙË Û˘Ì‚·ÙfiÙËÙ· ·fi ÙÔ˘˜ Û˘ÓÙÂÏÂÛÙ¤˜ ıÂÚÌÈ΋˜ ‰È·ÛÙÔÏ‹˜, Î·È ·˘Ùfi ‚ÂÏÙ›ˆÛË Î·Ù¿ ¿Û· Èı·ÓfiÙËÙ· ı· ÂÚÈÏ·Ì‚¿ÓÂÈ ÙË ‚ÂÏÙÈÛÙÔÔ›ËÛË Ù˘ ÛÎfiÓ˘ Û‡ÓıÂÛ˘126. øÛÙfiÛÔ, ‰ÂÓ ˘¿Ú¯Ô˘Ó Û·Ê›˜ ÂӉ›ÍÂȘ Ô˘ ·Ô‰ÂÈÎÓ‡Ô˘Ó ÙËÓ ·ÚÔ˘Û›· ÙˆÓ ¯ËÌÈÎÒÓ ‰ÂÛÌÒÓ ÌÂٷ͇ ˙ÈÚÎÔÓ›·˜ Î·È ÂÈÎ¿Ï˘„Ë ÎÂÚ·ÌÈο, ·Ó Î·È ˘¿Ú¯ÂÈ Ì›· ·Ó·ÊÔÚ¿126 Ô˘ ·Ó·Ê¤ÚÂÈ ¤Ó·Ó Ù¤ÙÔÈÔ ‰ÂÛÌfi. ™˘ÓÂÒ˜ ˘ÔÙ›ıÂÙ·È fiÙÈ Ë Ì˯·ÓÈ΋ ÚfiÛÊ˘ÛË ‰È·‰Ú·Ì·Ù›˙ÂÈ ÙÔ Ì›˙ÔÓ· ÚfiÏÔ ÛÙËÓ ÂÓۈ̿وÛË Ù˘ ÔÚÛÂÏ¿Ó˘ ÛÙË ˙ÈÚÎÔÓ›·. Hellenic Stomatological Review 57: 101-137, 2013 Fig. 12: Absence of metal allows light transmission through zirconia prosthesis use. Alongside the emergence of new zirconia materials such as as monolithic zirconia has solved the ceramic chipping disadvantage. There are plenty more applications of zirconia in dentistry, few of which have scientific and long-term evidence-based documentation. Some studies report cases with extreme applications of zirconia such as bars, precision attachments etc. Clinicians should be particularly cautious in accepting new undocumented applications that may be proposed by companies or dental laboratories. Some suspicions persist by clinicians as to the restorations behavior over time that should not be considered groundless. The great strength of the core material does not always guarantee longevity as there is always the risk of a sharp change in the behavior of the material due to aging. 125 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review 2) KATA°MATA ™YN¢E™MøN M›· ¿ÏÏË ÛÔ‚·Ú‹ ÂÈÏÔ΋ Ô˘ Ô‰ËÁ› ÙȘ ·ÔηٷÛÙ¿ÛÂȘ Û ·ÛÙÔ¯›· Â›Ó·È ÙÔ Î¿Ù·ÁÌ· ÙÔ˘ ÛÎÂÏÂÙÔ‡. ¶ÈÔ Û˘¯Ó¿ ÂÌÊ·Ó›˙ÔÓÙ·È ÛÙÔ˘˜ Û˘Ó‰¤ÛÌÔ˘˜. OÈ ÚÒÙ˜ ÎÈfiÏ·˜ ·ÔÙ˘¯›Â˜ Ô‰‹ÁËÛ·Ó ÛÙËÓ Î·ıȤڈÛË ·˘ÛÙËÚfiÙÂÚˆÓ ÎÚÈÙËÚ›ˆÓ ÁÈ· ÙȘ ‰È·ÛÙ¿ÛÂȘ ÛÎÂÏÂÙÔ‡ Î·È Û˘Ó‰¤ÛÌˆÓ Î·È ÛÙËÓ ˘ÈÔı¤ÙËÛË ÈÔ ÂÚÈÔÚÈÛÌ¤ÓˆÓ Û ¤ÎÙ·ÛË ·ÔηٷÛÙ¿ÛˆÓ5 (EÈÎ. 6). I‰È·›ÙÂÚË ÛËÌ·Û›· ¤¯ÂÈ Î·È Ô Û¯Â‰È·ÛÌfi˜ ÙˆÓ Û˘Ó‰¤ÛÌˆÓ fiÔ˘ Ú¤ÂÈ Ó· ·ÔʇÁÔÓÙ·È Ô͇·È¯Ì˜ ·ÔÏ‹ÍÂȘ Ô˘ Ô‰ËÁÔ‡Ó ·Ó·fiÊ¢ÎÙ· Û ÛËÌ›· Û˘ÁΤÓÙÚˆÛ˘ Ù¿ÛÂˆÓ (EÈÎ. 7&8). 3) A¶OKO§§H™H ¶PO™£ETIKøN EP°A™IøN H ·ÒÏÂÈ· Û˘ÁÎÚ¿ÙËÛ˘ (οٷÁÌ· Û˘ÁÎÔÏÏËÙÈ΋˜ ÎÔÓ›·˜) ÂÓfi˜ ÛÙËÚ›ÁÌ·ÙÔ˜ ·fi Ì›· ÚÔÛıÂÙÈ΋ ÂÚÁ·Û›· ‹ Ë ÂÍÔÏÔÎÏ‹ÚÔ˘ ·ÔÎfiÏÏËÛË ÌÈ·˜ ÚÔÛıÂÙÈ΋˜ ÂÚÁ·Û›·˜ ·fi Ù· Ô‰ÔÓÙÈο ÎÔÏÔ‚ÒÌ·Ù· ·ÔÙÂÏ› Ì›· ÛËÌ·ÓÙÈ΋ Ù¯ÓÈ΋ ÂÈÏÔ΋ Ô˘ ÂËÚ¿˙ÂÈ ÙËÓ ÂÈ‚›ˆÛ‹ Ù˘. E›Ó·È ‚¤‚·È· ‰˘Ó·Ù‹ Ë ¿ÌÂÛË Â·Ó·Û˘ÁÎfiÏÏËÛË Ù˘ ÂÚÁ·Û›·˜ ¯ˆÚ›˜ οÔÈ· ¿ÏÏË ÂÈÏÔ΋, ·ÏÏ¿ ÔÚÈṲ̂Ó˜ ÊÔÚ¤˜ ¿ÏϘ ‚ÈÔÏÔÁÈΤ˜ ÂÈÏÔΤ˜ fiˆ˜ ‰Â˘ÙÂÚÔÁÂÓ‹˜ ÙÂÚˉfiÓ· ‹ ·ÒÏÂÈ· ˙ˆÙÈÎfiÙËÙ·˜ ÂÈ‚¿ÏÏÔ˘Ó ÙËÓ ¿ÌÂÛË ·ÓÙÈηٿÛÙ·Û‹ Ù˘. H ·ÒÏÂÈ· Û˘ÁÎÚ¿ÙËÛ˘ Â›Ó·È Ôχ ¯·ÌËÏ‹˜ Û˘¯ÓfiÙËÙ·˜ ÂÈÏÔ΋ ÛÙȘ ÌÔÓ¤˜ ÛÙÂÊ¿Ó˜ ‹ Á¤Ê˘Ú˜127. ¶·ÚfiÏ· ·˘Ù¿ Ë ‰ÈÂÚ‡ÓËÛË ÙˆÓ ·ÈÙ›ˆÓ Ô˘ Ô‰ËÁÔ‡Ó ÛÙËÓ ·ÔÎfiÏÏËÛË ÙˆÓ ÚÔÛıÂÙÈÎÒÓ ÂÚÁ·ÛÈÒÓ ÌÔÚ› Ó· ‚ÔËı‹ÛÂÈ ÙËÓ ¤Ú¢ӷ ÁÈ· ÂÚÈÛÛfiÙÂÚÔ Ì·ÎÚÔ‚ÈfiÙÂÚ˜ ·ÔηٷÛÙ¿ÛÂȘ. H ‰È·‰Èηۛ· Ù˘ ÙÂÏÈ΋˜ Û˘ÁÎfiÏÏËÛ˘ ·ÔÙÂÏ› ÙÔ ÙÂÏÂ˘Ù·›Ô ÎÏÈÓÈÎfi ÛÙ¿‰ÈÔ Î·Ù·Û΢‹˜ ÌÈ·˜ ÚÔÛıÂÙÈ΋˜ ·ÔηٿÛÙ·Û˘. M ÙËÓ ÚÔ¸fiıÂÛË fiÙÈ Ù· ÚÔËÁÔ‡ÌÂÓ· ÛÙ¿‰È· ¤¯Ô˘Ó ÂÎÙÂÏÂÛÙ› ȉ·ÓÈο, Ë Û˘ÁÎfiÏÏËÛË ¤Ú¯ÂÙ·È ˆ˜ ÂÈÛÙ¤Á·ÛÌ· ÁÈ· ÙËÓ ÔÏÔÎÏ‹ÚˆÛË ÌÈ·˜ ·ÍÈfiÈÛÙ˘ ÚÔÛıÂÙÈ΋˜ ·ÔηٿÛÙ·Û˘. OÈ ÚÔ˜ Û˘ÁÎfiÏÏËÛË ÂÈÊ¿ÓÂȘ Ú¤ÂÈ Ó· ·Ô‰ÒÛÔ˘Ó ÙË Ì¤ÁÈÛÙË ÔÈfiÙËÙ· ‰ÂÛÌÔ‡ ¤ÙÛÈ ÒÛÙ ӷ ˘¿Ú¯ÂÈ ÌÈ· Ì·ÎÚÔ¯ÚfiÓÈ· ÂÈ‚›ˆÛË Ù˘ ÚÔÛıÂÙÈ΋˜ ·ÔηٿÛÙ·Û˘ Î·È Ó· ÂÏ·¯ÈÛÙÔÔÈËı› ÙÔ Ê·ÈÓfiÌÂÓÔ Ù˘ ÌÈÎÚԉțۉ˘Û˘. EÎÙfi˜ ·fi ÙËÓ ÂÈÊ¿ÓÂÈ· ÙÔ˘ Ô‰ÔÓÙÈÎÔ‡ ÎÔÏÔ‚ÒÌ·ÙÔ˜, Ë ÂÛˆÙÂÚÈ΋ ÂÈÊ¿ÓÂÈ· Ù˘ ÚÔÛıÂÙÈ΋˜ ÂÚÁ·Û›·˜ ˘Ê›ÛÙ·Ù·È ÙȘ ÂÚÈÛÛfiÙÂÚ˜ ÊÔÚ¤˜ οÔÈ· ÌÔÚÊ‹˜ ÂÂÍÂÚÁ·Û›· ÚÔÎÂÈ̤ÓÔ˘ Ó· ÈÛ¯˘ÚÔÔÈËı› Ô ‰ÂÛÌfi˜ Ì ÙÔ Ô‰ÔÓÙÈÎfi ÎÔÏfi‚ˆÌ·. H ȉȷÈÙÂÚfiÙËÙ· ÙˆÓ ·ÔηٷÛÙ¿ÛÂˆÓ Ì ÛÎÂÏÂÙfi ˙ÈÚÎÔÓ›·˜ ¤ÁÎÂÈÙ·È ÛÙÔ ÁÂÁÔÓfi˜ fiÙÈ ÏfiÁˆ Ù˘ ˘„ËÏ‹˜ ÛÎÏËÚfiÙËÙ·˜ Î·È ÎÚ˘ÛÙ·ÏÏÈÎfiÙËÙ·˜ Ù˘ ˙ÈÚÎÔÓ›· ·Ú·Ì¤ÓÔ˘Ó Û¯Â‰fiÓ ·ÓÂËÚ¤·ÛÙ˜ ·fi ÔÔÈ·‰‹ÔÙ ÂÊ·ÚÌÔ˙fiÌÂÓË ÂÂÍÂÚÁ·Û›·128. Œ¯Ô˘Ó Á›ÓÂÈ ÔÏϤ˜ ÂÈÚ·Ì·ÙÈΤ˜ ÚÔÛ¿ıÂȘ ÁÈ· ÙË ‚ÂÏÙ›ˆÛË ÙÔ˘ ‰ÂÛÌÔ‡ ÌÂٷ͇ ˙ÈÚÎÔÓ›·˜ Î·È ‰È¿ÊÔÚˆÓ ÎÔÓÈÒÓ Ì ‰È·ÊÔÚÂÙÈο ·ÔÙÂϤÛÌ·Ù·. Y¿Ú¯ÂÈ ·ÎfiÌË Â˘Ú‡ ÂÚ¢ÓËÙÈÎfi ‰›Ô ̤¯ÚÈ ÙËÓ Î·ıȤڈÛË Û˘ÁÎÂÎÚÈ̤ÓÔ˘ ÚˆÙÔÎfiÏÏÔ˘ Û˘ÁÎfiÏÏËÛ˘ ÙˆÓ ·ÔηٷÛÙ¿ÛÂˆÓ ˙ÈÚÎÔÓ›·˜ Ô˘ ÂӉ¯Ô̤ӈ˜ Ó· ÂÍ·Ï›„ÂÈ ÙË ‰˘Û¿ÚÂÛÙË ÂÈÏÔ΋ ·ÔÎfiÏÏËÛ˘ ÌÈ·˜ ·ÔηٿÛÙ·Û˘ ·fi ÙÔ Ô‰ÔÓÙÈÎfi ÛÙ‹ÚÈÁÌ·. K§INIKA ¶EPI™TATIKA 1) MÔÓ‹Ú˘ ÛÙÂÊ¿ÓË Ì ÛÎÂÏÂÙfi ˙ÈÚÎÔÓ›·˜ ÁÈ· ·ÓÙÈηٿÛÙ·ÛË ·Ï·È¿˜ ÌÂÙ·ÏÏÔÎÂÚ·ÌÈ΋˜ ÛÙÂÊ¿Ó˘ Û ·ÈÛıËÙÈ΋ ÂÚÈÔ¯‹ #11(EÈÎ. 9-12) 2) ™ÙÂÊ¿ÓË ÌÔÓÔÏÈıÈ΋˜ ˙ÈÚÎÔÓ›·˜ (EÈÎ. 13 ·-‰ &14 ·-‰) 126 13a 13b 13c 13d Fig. 13a-d: Monolithic zirconia crown a) buccal view b) occlusal view c) appliance of surface contamination inhibitor (Ivoclean, Ivoclar) Hellenic Stomatological Review 57: 101-137, 2013 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review 14a EÈÎ. 9·: AÚ¯È΋ ÂÈÎfiÓ· ıÚ·˘Ṳ̂Ó˘ ÌÂÙ·ÏÏÔÎÂÚ·ÌÈ΋˜ ÛÙÂÊ¿Ó˘ #21 14b EÈÎ. 9‚: AÚ¯È΋ ÂÈÎfiÓ· ıÚ·˘Ṳ̂Ó˘ ÌÂÙ·ÏÏÔÎÂÚ·ÌÈ΋˜ ÛÙÂÊ¿Ó˘ #21 (ÂÌÊ·Ó¤˜ ÙÔ ÌÂÙ·ÏÏÈÎfi ÛÂÈÚ‹ÙÈ ·˘¯ÂÓÈο) 14c EÈÎ. 10: ¢ÔÎÈÌ‹ ÛÎÂÏÂÙÔ‡ ˙ÈÚÎÔÓ›·˜ 14d EÈÎ. 11: H ÙÂÏÈ΋ ·ÔηٿÛÙ·ÛË Hellenic Stomatological Review 57: 101-137, 2013 Fig. 14a-d: Monolithic zirconia crown one month post final cementation (buccal and occlusal view) 127 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review EÈÎ. 12: H ·Ô˘Û›· ÌÂÙ¿ÏÏÔ˘ ÂÈÙÚ¤ÂÈ ‰È¿¯˘ÛË ÊˆÙfi˜ ̤۷ ·fi ÙËÓ ÚÔÛıÂÙÈ΋ ·ÔηٿÛÙ·ÛË ™YZHTH™H-™YM¶EPA™MATA T· ÔÏÔÎÂÚ·ÌÈο Û˘ÛÙ‹Ì·Ù· ˙ÈÚÎÔÓ›·˜ Ôχ ÁÚ‹ÁÔÚ· ÂÎÙfiÈÛ·Ó ¿ÏÏ· ÔÏÔÎÂÚ·ÌÈο Û˘ÛÙ‹Ì·Ù· Î·È ¤¯Ô˘Ó ‹‰Ë ·ÔÎÙ‹ÛÂÈ ¤Ó· ÌÂÁ¿ÏÔ ÌÂÚ›‰ÈÔ Ù˘ ·ÁÔÚ¿˜ ÙˆÓ ÔÏÔÎÂÚ·ÌÈÎÒÓ ·ÔηٷÛÙ¿ÛˆÓ. OÈ ÚÒÙ˜ 3ÂÙ›˜ Î·È 5ÂÙ›˜ ÌÂϤÙ˜ ‹Ù·Ó ȉȷ›ÙÂÚ· ÂÓı·ÚÚ˘ÓÙÈΤ˜ ÁÈ· ÙË Û˘ÌÂÚÈÊÔÚ¿ ÙÔ˘ ˘ÏÈÎÔ‡ ÛÙÔ ÛÙÔÌ·ÙÈÎfi ÂÚÈ‚¿ÏÏÔÓ Î·È Á›ÓÂÙ·È ÌÂÁ¿ÏË ÂÚ¢ÓËÙÈ΋ ÚÔÛ¿ıÂÈ· ÁÈ· ÙËÓ ÂÚ·ÈÙ¤Úˆ Ì›ˆÛË Î·È ÂÍ¿ÏÂÈ„Ë ÙˆÓ ÚÔ‚ÏËÌ¿ÙˆÓ Ô˘ ÚԤ΢„·Ó ηٿ ÙË ¯Ú‹ÛË Ù˘. ¶·Ú¿ÏÏËÏ· Ë ÂÌÊ¿ÓÈÛË Ó¤ˆÓ ˘ÏÈÎÒÓ ÌÔÓÔÏÈıÈ΋˜ ˙ÈÚÎÔÓ›·˜ ¤‰ˆÛ χÛË ÛÙȘ ·ÔÎÔÏÏ‹ÛÂȘ ÙÔ˘ ÂÈÎ·Ï˘ÙÈÎÔ‡ ÎÂÚ·ÌÈÎÔ‡. Y¿Ú¯ÂÈ ÏËıÒÚ· ϤÔÓ ÂÊ·ÚÌÔÁÒÓ Ù˘ ˙ÈÚÎÔÓ›·˜ ÛÙËÓ Ô‰ÔÓÙÈ·ÙÚÈ΋, ÂÏ¿¯ÈÛÙ˜ ·fi ÙȘ Ôԛ˜ ¤¯Ô˘Ó ÂÈÛÙËÌÔÓÈ΋ Î·È ‚È‚ÏÈÔÁÚ·ÊÈ΋ ÙÂÎÌËÚ›ˆÛË. ¶ÔÏϤ˜ ÊÔÚ¤˜ Ì¿ÏÈÛÙ· ·Ó·Ê¤ÚÔÓÙ·È ˆ˜ ·Ó·ÊÔÚ¤˜ ÂÚÈÙÒÛÂˆÓ ·ÎÚ·›Â˜ ÂÊ·ÚÌÔÁ¤˜ Ù˘ ˙ÈÚÎÔÓ›·˜ fiˆ˜ Û‡Ó‰ÂÛÌÔÈ ·ÎÚȂ›·˜, ‰ÔÎÔ› Î.¿. OÈ ÎÏÈÓÈÎÔ› Ú¤ÂÈ Ó· Â›Ó·È È‰È·›ÙÂÚ· ÂÈÊ˘Ï·ÎÙÈÎÔ› ÛÙËÓ ·Ô‰Ô¯‹ Ó¤ˆÓ ·ÙÂÎÌËÚ›ˆÙˆÓ ÂÊ·ÚÌÔÁÒÓ Ô˘ ÌÔÚ› Ó· ÚÔÙ·ıÔ‡Ó ·fi ÂÙ·ÈÚ›˜ ‹ Ô‰ÔÓÙÔÙ¯ÓÈο ÂÚÁ·ÛÙ‹ÚÈ·. OÚÈṲ̂Ó˜ ˘Ô„›Â˜ Ô˘ ÂÍ·ÎÔÏÔ˘ıÔ‡Ó Ó· ˘¿Ú¯Ô˘Ó ·fi ÙÔ˘˜ ÎÏÈÓÈÎÔ‡˜ ˆ˜ ÚÔ˜ ÙË Û˘ÌÂÚÈÊÔÚ¿ ÙˆÓ ·ÔηٷÛÙ¿ÛÂˆÓ Û ‚¿ıÔ˜ ¯ÚfiÓÔ˘ ‰ÂÓ Ú¤ÂÈ Ó· ıˆÚÔ‡ÓÙ·È ·‚¿ÛÈ̘. OÈ ÌÂÁ¿Ï˜ ·ÓÙÔ¯¤˜ ÙÔ˘ ˘ÏÈÎÔ‡ ˘Ú‹Ó· ‰ÂÓ ÂÁÁ˘ÒÓÙ·È ¿ÓÙÔÙ ̷ÎÚÔ‚ÈfiÙËÙ· ηıÒ˜ ˘¿Ú¯ÂÈ Ô Î›Ó‰˘ÓÔ˜ Ù˘ ·fiÙÔÌ˘ ÌÂÙ·‚ÔÏ‹˜ Ù˘ Û˘ÌÂÚÈÊÔÚ¿˜ ÙÔ˘ ˘ÏÈÎÔ‡ (Á‹Ú·ÓÛË)130. TÔ ÁÂÁÔÓfi˜ fiÙÈ ÙÔ ˘ÏÈÎfi ‰Â ¯ÚËÛÈÌÔÔÈÂ›Ù·È ÛÙËÓ ÔÚıԷȉÈ΋ ÚÔ‚ÏËÌ¿ÙÈÛ ÔÏÏÔ‡˜ ÎÏÈÓÈÎÔ‡˜ Ô‰ÔÓÙÈ¿ÙÚÔ˘˜. Afi ÙËÓ ¿ÏÏË ÏÂ˘Ú¿ Ë ·Ó¿Ù˘ÍË Î·È ÂͤÏÈÍË ÙˆÓ Û˘ÛÙËÌ¿ÙˆÓ Û¯Â‰È·ÛÌÔ‡ Î·È ÎÔ‹˜ Ì ÙË ‚Ô‹ıÂÈ· ËÏÂÎÙÚÔÓÈÎÒÓ ˘ÔÏÔÁÈÛÙÒÓ (CAD-CAM) ¤¯ÂÈ ÂÈÎÂÓÙÚˆı› ÛÙÔ ˘ÏÈÎfi Ù˘ ˙ÈÚÎÔÓ›·˜ Î·È ¤¯ÂÈ ÙÂÏÂ˘Ù·›· ‚ÂÏÙȈı› Ë ÔÈfiÙËÙ· ÔÚȷ΋˜ ÂÊ·ÚÌÔÁ‹˜, ÛËÌÂ›Ô ¤ÓÙÔÓ˘ ÎÚÈÙÈ΋˜ ÛÙ· ÚÒÙ· Û˘ÛÙ‹Ì·Ù·84. T· ÎÂÚ·ÌÈο ·ÏÔ˘Ì›Ó·˜ Î·È Ù· ÌÂÙ·ÏÏÈο ÎÚ¿Ì·Ù· Ê·›ÓÂÙ·È Ó· ÌËÓ ·ÔÙÂÏÔ‡Ó Ï¤ÔÓ ÙÔ Â›ÎÂÓÙÚÔ Ù˘ ÂͤÏÈ128 The fact that the material is not used any longer in clinical orthopedics raise doubts among dental professionals. On the other hand the growth and development of computer-aided design and cutting systems (CAD-CAM) have been focused on zirconia and have recently improved the fit accuracy, a point of criticism in the early systems. The alumina ceramics and metal alloys appear to no longer constitute the focus of development for CADCAM systems, and their commercial use is descending. Zirconia is a subject of basic research for the last ten years in dentistry at many levels. The three main axes of research investigation are its bond to the veneering porcelain, luting with contemporary cements and the improvement of its optical and mechanical properties. Alongside areas of research and development are related to similar materials such as composites of zirconia and alumina. Some attempts are currently in progress in the laser’s field, for cutting and processing zirconia with preliminary promising results. There are several issues on zirconia with the main disadvantage being the matastability of its structure and the non-controlled development of monoclinic phase that can lead to premature failures. However there is not enough long-term clinical documentation for total or partial acceptance of zirconia as a viable and reliable alternative to the classical metal-ceramic restorations. Finally, the application of zirconia as a biomaterial for dental implants does not seem to have nowdays the initial enthusiastic acceptance. Today, there are only a few manufacturers of zirconia implants. However, until now, the research done on zirconia implants is a small fraction of the widespread research on titanium alloy implants. REFERENCES 1. Zhao Z, Gou J: Improved fire retardancy of thermoset composites modified with carbon nanofibers Sci Technol Adv Mater 2009; 10: 1-6. 2. McLean J, Kedge M: High strength ceramics Quintessence Int 1987;18: 97-106. 3. Andritsakis D: All-Ceramic Aesthetic Reconstructions Athens1994 Parisianos publications. 4. Andritsakis D: Fixed Restorative Dentistry Athens 2002 Zacharopoulos publications. 5. Miyazaki T, Nakamura T, Matsumura H, Ban S, Kobayashi T: Current status of zirconia restoration. J Prosthodont Res 2013; 57 (4): 236-61. 6. Encyclopedia Britannica Online Zirconium (Zr) Web. 15 March 2012. 7. Piconi C, Maccauro G: Zirconia as a ceramic biomaterial Biomaterials 1999; 20: 1-25. 8. Mahiat Y: La Zircone: cette meconnue Strategie Prothetique 2006; 6 (1): 55-65. 9. Vagkopoulou T, Koutayas S, Koidis P, Strub J: Zirconia in dentistry: Part 1. Discovering the nature of an upcoming bioceramic The European Journal of Esthetic dentistry 2009; 4 (2): 2-23. 10. Hannink R, Kelly P, Muddle B: Transformation toughening in zirconia-containing ceramics. J Am Ceram Soc 2000; 83 (3): 461-87. Hellenic Stomatological Review 57: 101-137, 2013 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review 13· 13‚ 13Á 13‰ EÈÎ. 13 (·-‰): ÛÙÂÊ¿ÓË ÌÔÓÔÏÈıÈ΋˜ ˙ÈÚÎÔÓ›·˜ ·) ·ÚÂȷ΋ ¿Ô„Ë ‚) Ì·ÛËÙÈ΋ ¿Ô„Ë Á) ÙÔÔı¤ÙËÛË ·Ú¿ÁÔÓÙ· ·Ê·›ÚÂÛ˘ ÂÈÊ·ÓÂȷ΋˜ ÂÈÌfiÏ˘ÓÛ˘ (Ivoclean, Ivoclar) ‰) Ë ÛÙÂÊ¿ÓË ÚÈÓ ÙË Û˘ÁÎfiÏÏËÛË (T˙Ô‡Ù˙·˜ I.) Hellenic Stomatological Review 57: 101-137, 2013 11. Petropoulos P: Elastic properties of high technology ceramics PhD 2001 University of Patra. 12. Manicone P, Iommetti P, Raffaelli L: An overview of zirconia ceramic: Basic properties and clinical applications Journal of dentistry 2007; 35: 819-826. 13. Clarke I et al: Current status of zirconia used in total hip implants J Bone Joint Surg 2003; 85: 73-84. 14. Chevalier J: What future of zirconia as a biomaterial? Biomaterials 2006; 27: 535-543. 15. Masonis J, Bourne R, Ries, M, McCalden R, Salehi A, Kelman D: Zirconia femoral head fractures: a clinical and retrieval analysis. Journal of Arthroplasty 2004; 19: 898-905. 16. Fabbri P et al: Lifetime estimation of a zirconia-alumina composite for biomedical applications Dental Mater 2014; 30: 138-42. 17. Katakis D: University Inorganic Chemistry p.51 OEDB. 18. “Zirconium” The Columbia electronic Encyclopedia 6th edition 2007 editor Paul Lagasse. 19. Peterson J, McDonell M: Zirconium: Radiological and Chemical Fact Sheets to Support Health Risk Analyses for Contaminated Areas. Argonne National Laboratory 2007: 64-65. 20. Zirconium: How Products Are Made. Advameg Inc 2007: 1-6. 21. Giannakoudakis D: Lessons of General and Inorganic Chemistry 1970 University of Thessaloniki. 22. Denry I, Kelly R: State of the art of zirconia for dental applications Dental Materials 2008; 24: 299-307. 23. Kelly J, Denry I: Stabilized zirconia as a structural ceramic: An overview. Dent Mater 2008; 24: 289-298. 24. Shen T, Tien T, Chen I: Cubic- to -tetragonal (t’) transformation in zirconia coating systems. J Am Ceram Soc 1992; 75: 1505-16. 25. Evans A, Heuer A: Review-transformation toughening in ceramics: martensitic transformations in crack-tip stress fields. J Am Ceram Soc 1980; 63 (5-6): 241-8. 26. Tagmatarchis A: Surface characterization of dental ceramics on reinforced all-ceramic substrates Phd 2003. 27. Pessoa R, Cerqueira M, Nasar R, Yoshida I: Synthesis of stabilized zirconia without dopants Cerâmica 2008; 54:253258. 28. Garvie R, Hannink R, Pascoe R: Ceramic steel? Nature (London) 1975; 258: 703-4. 29. Claussen N, Ruhle M, Heuer AH, editors: Advances in ceramics, vol. 12. Science and Technology of Zirconia II. Columbus (OH, USA): The American Ceramic Society 1984: 325-51. 30. Heuer A: Transformation toughening in ZrO2-containing ceramics. J Am Ceram Soc 1987; 70 (10): 689-98. 31. Heuer A, Claussen N, Kriven W, Ruehle M: Stability of tetragonal ZrO2 particles in ceramic materials. J Am Ceram Soc 1982; 65 (12): 642-50. 32. Stevens R: Engineering Properties of Zirconia 1986 Magnesium Elektron Ltd. 33. Salomoni A, Tucci A, Esposito L, Stamenkovic I: Forming and sintering of multiphase bioceramics. J Mater Sci Mater Med 1994; 5: 651-3. 34. Deville S, Chevalier J: Martensitic Relief Observation by Atomic Force Microscopy in Yttria-Stabilized Zirconia J Am Ceram Soc 2003; 86 (12): 225-27. 35. Basu D, Gupta M, Basu M, Sarkar B: Ageing of zirconiatoughened alumina ceramics J of the European Ceramic Society 1996; 16: 613-617. 36. Lunghi V, Sergo V: Low temperature degradation-aging-of zirconia: A critical review of relevant aspects in dentistry Dental Materials 2010; 26: 807-820. 129 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review 14· 14‚ 14Á 14‰ EÈÎ. 14·-‰: ™ÙÂÊ¿ÓË ÌÔÓÔÏÈıÈ΋˜ ˙ÈÚÎÔÓ›·˜ ¤Ó· Ì‹Ó· ÌÂÙ¿ ÙËÓ ÙÂÏÈ΋ Û˘ÁÎfiÏÏËÛË (·ÚÂȷ΋ Î·È Ì·ÛËÙÈ΋ ¿Ô„Ë) (T˙Ô‡Ù˙·˜ I.) 130 37. Magnani G, Brillante A: Effect of the composition and sintering process on mechanical properties and residual stresses in zirconia-alumina composites Journal of the European Ceramic Society 2005; 25: 3383-3392. 38. Maccauro G, Bianchino G, Sangiorgi S, Magnani G, Marotta D, Manicone PF, Raffaelli L, Rossi Iommetti P, Stewart A, Cittadini A, Sgambato A: Development of a new zirconiatoughened alumina: promising mechanical properties and absence of in vitro carcinogenicity. Int J Immunopathol Pharmacol 2009 Jul-Sep; 22 (3): 773-9. 39. Chai J, Chu F, Chow T, Liang B: Chemical solubility and FS of Zirconia based ceramics. Int J Prosthodont 2007; 20: 587-595. 40. Christel P, Meunier A, Heller M, Torre J, Peile C: Mechanical properties and short-term in vivo evaluation of yttriumoxide-parially-stabilized zirconia. J Biomed Mater Res 1989; 23: 45-61. 41. Montross C: Comparison of bulk properties of Mg-PSZ with temperature- time contour diagrams. J Am Ceram Soc 1993; 76 (8): 1993-7. 42. Green D, Hannink R, Swain M: TransfÔrmation Toughening of Ceramics. CRC Press, Boca Raton. FL, 1989: 98-103. 43. Hannink R, Howard C, Kisi E, Swain M: Relationship between fracture toughness and phase assemblage in MgPSZ. J Am Ceram Soc 1994; 77: 571-579. 44. Sundh A, Sjoegren G: Fracture resistance of all-ceramic zirconia bridges with differing phase stabilizers and quality of sintering. Dent Mater 2006; 22: 778-84. 45. Gupta T, Bechtold J, Kuznicki R, Cadoff L, Rossing B: Stabilization of tetragonal phase in polycrystalline zirconia J Mater Sci 1977; 12 (12): 2421-6. 46. Gupta T, Lange F, Bechtold J: Effect of stress induced phase transformation on the properties of polycrystalline zirconia containing metastable tetragonal phase J Mater Sci 1978; 13: 1464-70. 47. Ruiz L, Readey M: Effect of heat-treatment on grain size, phase assemblage, and mechanical properties of 3 mol% Y-TZP J Am Ceram Soc 1996; 79 (9): 2331-40. 48. Chevalier J, Deville S, Munch E, Jullian R, Lair F: Critical effect of cubic phase on aging in 3mol% yttria-stabilized zirconia ceramics for hip replacement prosthesis Biomaterials 2004; 25 (24): 5539-45. 49. Aboushelib M, Kleverlaan C, Feilzer A: Evaluation of a High Fracture Toughness Composite Ceramic for Dental Applications J of Prosthodontics 2008; 17 :538-544. 50. Sato T, Ohtaki S, Endo T, Shimada M: Transformation of yttria-doped tetragonal ZrO2 polycrystals by annealing in controlled humidity conditions J Am Ceram Soc 1985; 168: 356-9. 51. Yi Y, Wang C, Wen N, Lin Y, Tian J: Structure and properties of colored dental tetragonal zirconia stabilized by yttrium ceramics. Hua Xi Kou Qiang Yi Xue Za Zhi. 2009 Oct; 27 (5): 473-8(abstract). 52. Zhang Y, Sailer I, Lawn B: Fatigue of dental ceramics J of Dentistry 2013; 41: 1135-47. 53. Zhang Y, Lee J, Srikanth R, Lawn B: Edge chipping and flexural resistance of monolithic ceramics. Dent Mater 2013; 29 (12): 1201-8. 54. Boulouz M, Boulouz, A, Giani A, Boyer A: Influence of substrate temperature and target composition on the properties of yttria-stabilized zirconia thin films grown by r.f. reactive magnetron sputtering Thin Solid Films 1998; 323: 85-92. 55. Heffernan M et al: Relative translucency of six all-ceramic systems: Part II J Prosthet Dent 2002; 88: 10-5. Hellenic Stomatological Review 57: 101-137, 2013 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review ͢ ÁÈ· Ù· CAD-CAM Û˘ÛÙ‹Ì·Ù· Î·È Ë ÂÌÔÚÈ΋ ÙÔ˘˜ ÔÚ›· Â›Ó·È Êı›ÓÔ˘Û·. H ˙ÈÚÎÔÓ›· ·ÔÙÂÏ› ·ÓÙÈΛÌÂÓÔ ÌÂϤÙ˘ Ù· ÙÂÏÂ˘Ù·›· ‰¤Î· ¯ÚfiÓÈ· ÛÙËÓ O‰ÔÓÙÈ·ÙÚÈ΋ Û ÔÏÏ¿ ›‰·. OÈ ÙÚÂȘ ‚·ÛÈÎÔ› ¿ÍÔÓ˜ ÌÂϤÙ˘ Â›Ó·È Ë Û‡Ó‰ÂÛË Ì ÙËÓ ÔÚÛÂÏ¿ÓË, Ë Û˘ÁÎfiÏÏËÛË Ì ٷ Û‡Á¯ÚÔÓ· ̤۷ Î·È Ë ‚ÂÏÙ›ˆÛË ÙˆÓ ÔÙÈÎÒÓ Î·È Ì˯·ÓÈÎÒÓ È‰ÈÔًوÓ. ¶·Ú¿ÏÏËÏ· ·Ó·Ù‡ÛÛÔÓÙ·È Î·È ÙÔÌ›˜ Ô˘ ·ÊÔÚÔ‡Ó Û ·ÚÂÌÊÂÚ‹ ˘ÏÈο fiˆ˜ ÛÙ· Û‡ÓıÂÙ· ˘ÏÈο ˙ÈÚÎÔÓ›·˜·ÏÔ˘Ì›Ó·˜. K¿ÔȘ ÚÔÛ¿ıÂȘ Á›ÓÔÓÙ·È ·ÎfiÌ· ÛÙÔÓ ÙÔ̤· Ù˘ ÂÊ·ÚÌÔÁ‹˜ laser ÁÈ· ÙËÓ ÎÔ‹ Î·È ÂÂÍÂÚÁ·Û›· ÙˆÓ ˘ÏÈÎÒÓ ˙ÈÚÎÔÓ›·˜ Ì ˘ÔÛ¯fiÌÂÓ· ·ÔÙÂϤÛÌ·Ù·. Y¿Ú¯Ô˘Ó ·ÚÎÂÙ¿ ˙ËÙ‹Ì·Ù· Û¯ÂÙÈο Ì ÙÔ ˘ÏÈÎfi Ù˘ ˙ÈÚÎÔÓ›·˜ Ì ‚·ÛÈÎfiÙÂÚÔ ÌÂÈÔÓ¤ÎÙËÌ· ÙËÓ ·ÛÙ¿ıÂÈ· ‰ÔÌ‹˜ Î·È ÙË ÌË ÂÏÂÁ¯fiÌÂÓË ·Ó¿Ù˘ÍË Ù˘ ÌÔÓÔÎÏÈÓÔ‡˜ Ê¿Û˘ Ô˘ ÌÔÚ› Ó· Ô‰ËÁ‹ÛÂÈ ÙÔ ˘ÏÈÎfi Û ÚÒÈÌË ·ÛÙÔ¯›·. T·˘Ùfi¯ÚÔÓ·, ÙÔ ÁÂÁÔÓfi˜ fiÙÈ ‰ÂÓ ˘¿Ú¯Ô˘Ó Ì·ÎÚfi¯ÚÔÓ˜ ÌÂϤÙ˜ ÂÈ‚›ˆÛ˘ ÙˆÓ ·ÔηٷÛÙ¿ÛÂˆÓ ˙ÈÚÎÔÓ›·˜, ηıÈÛÙ¿ ÂÏÏÈ‹ ÙËÓ ÙÂÎÌËÚ›ˆÛË ÁÈ· ÙËÓ Î·ıÔÏÈ΋ ‹ ÌÂÚÈ΋ ·Ô‰Ô¯‹ ÙÔ˘ ˆ˜ ·ÍÈfiÈÛÙ˘ ÂÓ·ÏÏ·ÎÙÈ΋˜ χÛ˘ ÙˆÓ ÎÏ·ÛÈÎÒÓ ÌÂÙ·ÏÏÔÎÂÚ·ÌÈÎÒÓ ·ÔηٷÛÙ¿ÛˆÓ. T¤ÏÔ˜ Ë ÂÊ·ÚÌÔÁ‹ Ù˘ ˙ÈÚÎÔÓ›·˜ ˆ˜ Ô‰ÔÓÙÈ·ÙÚÈÎÔ‡ ‚ÈÔ¸ÏÈÎÔ‡ ÂÌÊ˘ÙÂ˘Ì¿ÙˆÓ ‰Â Ê·›ÓÂÙ·È Ó· ¤¯ÂÈ Û‹ÌÂÚ· ÙËÓ ·Ú¯È΋ ÂÓıÔ˘ÛÈÒ‰Ë ·Ô‰Ô¯‹, fiˆ˜ ‰È·Ê·›ÓÂÙ·È ·fi ÙÔ˘˜ ÂÏ¿¯ÈÛÙÔ˘˜ ϤÔÓ Î·Ù·Û΢·ÛÙ¤˜ ÂÌÊ˘ÙÂ˘Ì¿ÙˆÓ ˙ÈÚÎÔÓ›·˜. H ¤Ú¢ӷ Ô˘ Á›ÓÂÙ·È Û¯ÂÙÈο Ì ÙË ˙ÈÚÎÔÓ›· Â›Ó·È ¤Ó· ÌÈÎÚfi ÎÏ¿ÛÌ· Ù˘ Â˘Ú‡Ù·Ù˘ ¤Ú¢ӷ˜ ÁÈ· Ù· ÂÌÊ˘Ù‡̷ٷ ÎÚ·Ì¿ÙˆÓ ÙÈÙ·Ó›Ô˘. BIB§IO°PAºIA 1. Zhao Z, Gou J: Improved fire retardancy of thermoset composites modified with carbon nanofibers Sci Technol Adv Mater 2009; 10:1-6. 2. McLean J, Kedge M: High strength ceramics Quintessence Int 1987;18: 97-106. 3. AÓ‰ÚÈÙÛ¿Î˘ ¢: OÏÔÎÂÚ·ÌÈΤ˜ AÈÛıËÙÈΤ˜ AÔηٷÛÙ¿ÛÂȘ Aı‹Ó· 1994 EΉfiÛÂȘ ¶·ÚÈÛÈ¿ÓÔ˜. 4. AÓ‰ÚÈÙÛ¿Î˘ ¢: AΛÓËÙË E·ÓÔÚıˆÙÈ΋ O‰ÔÓÙÈ·ÙÚÈ΋ Aı‹Ó· 2002 EΉfiÛÂȘ Z·¯·ÚfiÔ˘ÏÔ˜. 5. Miyazaki T, Nakamura T, Matsumura H, Ban S, Kobayashi T: Current status of zirconia restoration. J Prosthodont Res 2013; 57 (4): 236-61. 6. Encyclopedia Britannica Online Zirconium (Zr) Web. 15 March 2012. 7. Piconi C, Maccauro G: Zirconia as a ceramic biomaterial Biomaterials 1999; 20: 1-25. 8. Mahiat Y: La Zircone: cette meconnue Strategie Prothetique 2006; 6 (1): 55-65. 9. Vagkopoulou T, Koutayas S, Koidis P, Strub J: Zirconia in dentistry: Part 1. Discovering the nature of an upcoming bioceramic The European Journal of Esthetic dentistry 2009; 4 (2): 2-23. 10. Hannink R, Kelly P, Muddle B: Transformation toughening in zirconia-containing ceramics. J Am Ceram Soc 2000; 83 (3): 461-87. 11 ¶ÂÙÚfiÔ˘ÏÔ˜ ¶: EÏ·ÛÙÈΤ˜ I‰ÈfiÙËÙ˜ ÎÂÚ·ÌÈÎÒÓ ˘ÏÈÎÒÓ ˘„ËÏ‹˜ Ù¯ÓÔÏÔÁ›·˜ ¢È‰·ÎÙÔÚÈ΋ ¢È·ÙÚÈ‚‹ 2001 ¶·ÓÂÈÛÙ‹ÌÈÔ ¶·ÙÚÒÓ. 12. Manicone P, Iommetti P, Raffaelli L: An overview of zirconia ceramic: Basic properties and clinical applications Journal of dentistry 2007; 35: 819-826. Hellenic Stomatological Review 57: 101-137, 2013 56. Niafas Ch: Total hip replacement and high speed ceramic process PhD 2009 NTUOA. 57. Theunissen G, Bouma J, Winnbst A: Mechanical properties of ultra fine grained zirconia ceramics Journal of materials Science 1992; 27: 4429-4438. 58. Jasinski P, Petrovsky V, Toshio S, Petrovsky T, Anderson H: Electrical properties of YSZ films prepared by net shape technology J of the Electrochemical Society 2005; 152 (2): A454-A458. 59. Garcia R, Ussui V, de Lima N, Muccillo E, Lazar D: Physical properties of alumina/yttria-stabilized zirconia composites with improved microstructure Journal of Alloys and Compounds 2009; 486 (1-2): 747-753. 60. Rigney M, Funkenbusch E, Carr P: Physical and chemical characterization of microporous zirconia Journal of Chromatography 1990; 499: 291-304. 61. Wang C, Ong S, Xu P, Chen C: Electrical properties of crystalline YSZ films on silicon as alternative gate dielectrics Semicon Sci Technol 2001; 16: 13-16. 62. Bengisu M: Engineering ceramics Spinger 2007. 63. Badwal S, Drennan J: Grain boundary sensitivity in Y-TZP materials as a function of thermal history J Mater Sci 24 (1989): 88-96. 64. Chen C, Hsiang H, Hsu S: Preparation and characterization of Y-TZP powders coated with alumina Journal of Ceramic Processing Research 2008; 8: 131-134. 65. Hannink R, Kelly P, Muddle B: Transformation Toughening in Zirconia-Containing Ceramics J Am Ceram Soc, 2000; 83 (3): 461-87. 66. Komine F, Blatz M, Matsumura H: Current status of zirconiabased fixed restorations Journal Oral Science 2010; 52 (4): 531-539. 67. Parker R: Use of zirconia in restorative dentistry Dent Today 2007; 26 (3): 114-112. 68. Al-Amleh B, Lyons K, Swai M: Clinical trials in zirconia: a systematic review J of Oral Rehabil 2010; 37: 641-652. 69. Griggs JA: Recent advances in materials for all-ceramic restorations. Dent Clin North Am 2007; 51 (3):713-27. 70. Creugers N, Kayser A, Van’t Hoff M: A meta-analysis of durability data on conventional fixed bridges. Community Dent Oral Epidemiol 1994; 22: 448-452. 71. Lucarroti P, Burke F: Analysis of an administrative database of indirect restorations over 11 years Journal of Dentistry 2009; 37: 4-11. 72. Sadan A, Blatz M, Lang B: Clinical considerations for densely sintered alumina and zirconia restorations: part 1 Int J Per Rest Dent 2005; 25: 213-219. 73. Bahhav V, Aras M: Zirconia-based fixed partial dentures: a clinical review Quintessence Int 2011; 42: 173-182. 74. Koutayas S, Vagkopoulou T, Pelekanos S, Koidis P, Strub J: Zirconia in dentistry: Part 2. Evidence-based clinical breakthrough The European Journal of Esthetic dentistry 2009; 4 (2): 348-380. 75. Akbar J, Petrie C, Walker M, Williams K, Eick J: Marginal adaptation of Cerec 3 CAD/CAM composite crowns using two different finish line preparation designs. J Prosthodont 2006; 15 (3): 155-63. 76. McLaren E, Hyo L: CAD/CAM update: technologies and materials and clinical perspectives Inside Dentistry 2006; Nov/Dec: 98-103. 77. Reich S, Petschelt A, Lohbauer U: The effect of finish line preparation and layer thickness on the failure load and fractography of ZrO2 copings. J Prosthet Dent 2008 May; 99 (5): 369-76. 131 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review 13. Clarke I et al: Current status of zirconia used in total hip implants J Bone Joint Surg 2003; 85: 73-84. 14. Chevalier J: What future of zirconia as a biomaterial? Biomaterials 2006; 27: 535-543. 15. Masonis J, Bourne R, Ries, M, McCalden R, Salehi A, Kelman D: Zirconia femoral head fractures: a clinical and retrieval analysis. Journal of Arthroplasty 2004; 19: 898-905. 16. Fabbri P et al: Lifetime estimation of a zirconia-alumina composite for biomedical applications Dental Mater 2013; XXX-XXX. 17. K·Ù¿ÎË ¢, ¶ÓÂ˘Ì·ÙÈοÎË °: ¶·ÓÂÈÛÙËÌȷ΋ AÓfiÚÁ·ÓÔ˜ XËÌ›· ÙfiÌÔ˜ A’ ÛÂÏ. 51 OE¢B. 18. “Zirconium” The Columbia electronic Encyclopedia 6th edition 2007 editor Paul Lagasse. 19. Peterson J, McDonell M: Zirconium: Radiological and Chemical Fact Sheets to Support Health Risk Analyses for Contaminated Areas. Argonne National Laboratory 2007: 64-65. 20. Zirconium: How Products Are Made. Advameg Inc. 2007: 1-6. 21. °È·ÓÓ·ÎÔ˘‰¿Î˘ ¢A, M·ÓÔ˘Û¿Î˘ °E: M·ı‹Ì·Ù· °ÂÓÈ΋˜ Î·È AÓÔÚÁ¿ÓÔ˘ XËÌ›·˜, 1970 ¶·ÓÂÈÛÙ‹ÌÈÔ £ÂÛÛ·ÏÔӛ΢. 22. Denry I, Kelly R: State of the art of zirconia for dental applications Dental Materials 2008; 24: 299-307. 23. Kelly J, Denry I: Stabilized zirconia as a structural ceramic: An overview. Dent Mater 2008; 24: 289-298. 24. Shen T, Tien T, Chen I: Cubic- to -tetragonal (t’) transformation in zirconia coating systems. J Am Ceram Soc 1992; 75: 1505-16. 25. Evans A, Heuer A: Review-transformation toughening in ceramics: martensitic transformations in crack-tip stress fields. J Am Ceram Soc 1980; 63 (5-6): 241-8. 26. T·Á̷ٿگ˘ A: X·Ú·ÎÙËÚÈÛÌfi˜ Ù˘ ‰ÈÂÈÊ¿ÓÂÈ·˜ Ô‰ÔÓÙÈ·ÙÚÈÎÒÓ ÎÂÚ·ÌÈÎÒÓ ÂÈηχ„ÂˆÓ Â› ÂÓÈÛ¯˘Ì¤ÓˆÓ ÔÏÔÎÂÚ·ÌÈÎÒÓ ˘ÔÛÙÚˆÌ¿ÙˆÓ Aı‹Ó· 2003 ¢È‰·ÎÙÔÚÈ΋ ¢È·ÙÚÈ‚‹. 27. Pessoa R, Cerqueira M, Nasar R, Yoshida I: Synthesis of stabilized zirconia without dopants Cerâmica 2008; 54: 253-258. 28. Garvie R, Hannink R, Pascoe R: Ceramic steel? Nature (London) 1975; 258: 703-4. 29. Claussen N, Ruhle M, Heuer AH editors: Advances in ceramics, vol. 12. Science and Technology of Zirconia II. Columbus (OH, USA): The American Ceramic Society 1984: 325-51. 30. Heuer A: Transformation toughening in ZrO2-containing ceramics. J Am Ceram Soc 1987; 70 (10): 689-98. 31. Heuer A, Claussen N, Kriven W, Ruehle M: Stability of tetragonal ZrO2 particles in ceramic materials. J Am Ceram Soc 1982; 65 (12): 642-50. 32. Stevens R: Engineering Properties of Zirconia 1986 Magnesium Elektron Ltd. 33. Salomoni A, Tucci A, Esposito L, Stamenkovic I: Forming and sintering of multiphase bioceramics. J Mater Sci Mater Med 1994; 5: 651-3. 34. Deville S, Chevalier J: Martensitic Relief Observation by Atomic Force Microscopy in Yttria-Stabilized Zirconia J Am Ceram Soc 2003; 86 (12): 225-27. 35. Basu D, Gupta M, Basu M, Sarkar B: Ageing of zirconiatoughened alumina ceramics J of the European Ceramic Society 1996; 16: 613-617. 36. Lunghi V, Sergo V: Low temperature degradation-aging-of zirconia: A critical review of relevant aspects in dentistry Dental Materials 2010; 26: 807-820. 37. Magnani G, Brillante A: Effect of the composition and sintering process on mechanical properties and residual stresses in zirconia-alumina composites Journal of the European Ceramic Society 2005; 25: 3383-3392. 132 78. Lin M et al: The effect of tooth preparation form on the fit of Procera copings Int J Prosthodont 1998; 11: 580-90. 79. Conrad H, Seong W, Pesun I: Current ceramc materials and systems with clinical recommendations: A systematic review J Prosthet Dent 2007; 98: 389-404. 80. Pogoncheff C, Duff R: Use of zirconia collar to prevent interproximal porcelain fracture: a clinical report J Prosthet Dent 2010; 104: 77-79. 81. Tinschert J et al: Clinical behavior of zirconia-based fixed partial dentures made of DC-Zirkon: 3 years results Int J Prosthodont 2008; 21: 217-222. 82. Sailer I, Gottner J, Kanel S, Hammerle C: Randomized controlled clinical trial of zirconia-ceramic and metal-ceramic posterior FPDs. A 3-year follow up Int J Prosthodont 2009; 22: 553-560. 83. Beuer F, Edelhoff D, Gernet W, Sorensen J: Three-year clinical prospective evaluation of zirconia-based posterior fixed dental prostheses Clin Oral Invest 2009; 13: 445-451. 84. Cehreli M, Kokat A, Akca K: CAD/CAM Zirconia Vs. slip-cast glass-infiltrated alumina/zirconia all-ceramic crowns: 2year results of a randomized controlled clinical trial J Appl Oral Sci 2009; 17 (1): 49-55. ’ 85. Suarez M, Lozano J, Paz Salido M, Mart›nez F: Three-year clinical evaluation of In-Ceram Zirconia posterior FPDs The International Journal of Prosthodontics 2004; 17 (1): 35-8. 86. Ozkurt Z, Kazazoglu E: Clinical success of zirconia in dental applications J of Prosthodont 2010; 19: 64-68. 87. Carracho J, Razoog M: Removable partial denture abutments restored with all-ceramic surveyed crowns Quintessence Int 2006; 37: 283-288. 88. Pellechia R, Kang K, Hirayama H: Fixed partial denture supported by all-ceramic copings: a clinical report J Prosthet Dent 2004; 92: 220-3. 89. Chevalier J, Cales B, Drouin J: Low-temperature aging of YTZP ceramics J Am Ceram Soc 1999; 82: 2150-2154. 90. Larsson C et al: Fracture strength of four unit YTZP FPD cores designed with varying connector diameter. An in vitro study J Oral Rehab 2007; 34: 702-709. 91. Sundh A, Molin M, Sjogren G: Fracture resistance of yttrium oxide partially stabilized zirconia all-ceramic bridges after veneering and mechanical fatigue testing Dental Materials 2005; 21: 476-482. 92. Vult von Steyern P: All-ceramic fixed partial dentures. Studies on aluminum oxide- and zirconium dioxide-based ceramic systems. Swed Dent J Suppl 2005; (173): 1-69. 93. Kamposiora P, Papavasiliou G, Bayne S, Felton D: Stress concentration in all-ceramic posterior fixed partial dentures Quintessence Int 1996; 27: 701-706. 94. Studart R, Filser F, Kocher P, Gauckler L: Fatigue of zirconia under cyclic loading in water and its implications for the design of dental bridges. Dent Mater 2007; 23 (1): 106-14. 95. Guazzato M, Albakry M, Swain M, Ironside J: Mechanical properties of In-Ceram alumina and In-ceram Zirconia Int J Prostodont 2002; 15: 339-346. 96. Schmitt J et al: Zirconia posterior fixed partial dentures: A prospective clinical 3-year follow up Int J Prosthodont 2009; 22: 597-603. 97. Bicaro L, Bonfiglioli R, Soattin M, Vigolo P: An in vivo evaluation of fit ofzirconium-oxide based ceramic single crowns, generated with two CAD/CAM systems, in comparison to metal ceramic single crowns. J Prosthodont 2013; 22: 36-41. 98. Komine F, Gerds T, Witkowski S, Strub J: Influence of framework configuration on the marginal adaptation of zirconium dioxide ceramic anterior four-unit frameworks. Acta Odontol Scand 2005; 63: 361-6. Hellenic Stomatological Review 57: 101-137, 2013 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review 38. Maccauro G, Bianchino G, Sangiorgi S, Magnani G, Marotta D, Manicone PF, Raffaelli L, Rossi Iommetti P, Stewart A, Cittadini A, Sgambato A: Development of a new zirconiatoughened alumina: promising mechanical properties and absence of in vitro carcinogenicity. Int J Immunopathol Pharmacol. 2009 Jul-Sep; 22 (3): 773-9. 39. Chai J, Chu F, Chow T, Liang B: Chemical solubility and FS of Zirconia based ceramics. Int J Prosthodont 2007; 20: 587-595. 40. Christel P, Meunier A, Heller M, Torre J, Peile C: Mechanical properties and short-term in vivo evaluation of yttriumoxide-parially-stabilized zirconia. J Biomed Mater Res 1989; 23: 45-61. 41. Montross C: Comparison of bulk properties of Mg-PSZ with temperature- time contour diagrams. J Am Ceram Soc 1993; 76 (8): 1993-7. 42. Green D, Hannink R, Swain M: TransfÔrmation Toughening of Ceramics. CRC Press, Boca Raton. FL, 1989: 98-103. 43. Hannink R, Howard C, Kisi E, Swain M: Relationship between fracture toughness and phase assemblage in MgPSZ. J Am Ceram Soc 1994; 77: 571-579. 44. Sundh A, Sjoegren G: Fracture resistance of all-ceramic zirconia bridges with differing phase stabilizers and quality of sintering. Dent Mater 2006; 22: 778-84. 45. Gupta T, Bechtold J, Kuznicki R, Cadoff L, Rossing B: Stabilization of tetragonal phase in polycrystalline zirconia J Mater Sci 1977; 12 (12): 2421-6. 46. Gupta T, Lange F, Bechtold J: Effect of stress induced phase transformation on the properties of polycrystalline zirconia containing metastable tetragonal phase J Mater Sci 1978; 13: 1464-70. 47. Ruiz L, Readey M: Effect of heat-treatment on grain size, phase assemblage, and mechanical properties of 3 mol% Y-TZP J Am Ceram Soc 1996; 79 (9): 2331-40. 48. Chevalier J, Deville S, Munch E, Jullian R, Lair F: Critical effect of cubic phase on aging in 3mol% yttria-stabilized zirconia ceramics for hip replacement prosthesis Biomaterials 2004; 25 (24): 5539-45. 49. Aboushelib M, Kleverlaan C, Feilzer A: Evaluation of a High Fracture Toughness Composite Ceramic for Dental Applications J of Prosthodontics 2008; 17: 538-544. 50. Sato T, Ohtaki S, Endo T, Shimada M: Transformation of yttriadoped tetragonal ZrO2 polycrystals by annealing in controlled humidity conditions J Am Ceram Soc 1985; 168: 356-9. 51. Yi Y, Wang C, Wen N, Lin Y, Tian J: Structure and properties of colored dental tetragonal zirconia stabilized by yttrium ceramics. Hua Xi Kou Qiang Yi Xue Za Zhi. 2009 Oct; 27 (5): 473-8 (abstract). 52. Zhang Y, Sailer I, Lawn B: Fatigue of dental ceramics J of Dentistry 2013; 41: 1135-47. 53. Zhang Y, Lee J, Srikanth R, Lawn B: Edge chipping and flexural resistance of monolithic ceramics. Dent Mater 2013; 29 (12): 1201-8. 54. Boulouz M, Boulouz A, Giani A, Boyer A: Influence of substrate temperature and target composition on the properties of yttria-stabilized zirconia thin films grown by r.f. reactive magnetron sputtering Thin Solid Films 1998; 323: 85-92. 55. Heffernan M et al: Relative translucency of six all-ceramic systems: Part II J Prosthet Dent 2002; 88: 10-5. 56. NÈ¿Ê·˜ X: OÏÈ΋ ·ÚıÚÔÏ·ÛÙÈ΋ Î·È Î·ÙÂÚÁ·Û›· ˘„ËÏÒÓ Ù·¯˘Ù‹ÙˆÓ ÎÂÚ·ÌÈÎÒÓ ˘ÏÈÎÒÓ ¢È‰·ÎÙÔÚÈ΋ ¢È·ÙÚÈ‚‹ 2009(EM¶). 57. Theunissen G, Bouma J,Winnbst A: Mechanical properties of ultra fine grained zirconia ceramics Journal of materials Science 1992; 27: 4429-4438. 58. Jasinski P, Petrovsky V, Toshio S, Petrovsky T, Anderson H: Hellenic Stomatological Review 57: 101-137, 2013 99. Bindl A., Mormann W: Marginal and internal fit of all-ceramic CAD/CAM crown-copings on chamfer preparations J of Oral Rehab 2005; 32: 441-447. 100. Att W et al: Marginal adaptation of three different zirconium dioxide three unit fixed dental prostheses J Prosthet Dent 2009; 101: 239-247. 101. Mehl C, Ludwig K, Steiner M, Kern M: Fracture strength of prefabricated all-ceramic inlay-retained fixed dental prostheses Dental Materials 2010; 26: 67-75. 102. Edelhoff D, Sorensen J: Tooth structure removal associated with various preparation designs for posterior teeth. J Prosthet Dent 2002; 22: 241-9. 103. Abou Tara M, Eschbach S, Wolfart S, Kern M: Zirconia ceramic inlay-retained fixed dental prostheses - first clinical results with a new design J Dent 2011 Mar; 39 (3): 208-11. 104. Wolfart S, Ludwig K, Uphaus A, Kern M: Fracture strength of all ceramic posterior inlay retained fixed partial dentures Dental Materials 2007; 23: 1513-1520. 105. Wolfart S, Bohlsen F, Wegner S K, Kern M: A prospective evaluation up to five years of all ceramic crown and inlay retained FPDs Int J Prosthodont 2005; 18: 497-505. 106. Rossentritt M et al: Zirconia resin-bonded fixed partial dentures in the anterior maxilla Quintessence Int 2008; 39: 313-319. 107. Walker: Effect of simulated resin-bonded fixed partial denture clinical conditions on resin cement mechanical properties Journal of Oral Rehabilitation 2003; 30: 837-846. 108. Duarte S et al: Resin Bonded fixed partial dentures with a new modified zirconia surface: a clinical report J Prosthet Dent 2009; 102: 68-73. 109. Bergman B, Lundquist P, Sjögren U, Sundquist G: Restorative and endodontic results after treatment with cast posts and cores J Prosthet Dent 1989; 61 (1): 10-5. 110. Nothdurft F, Pospiech P: Clinical evaluation of pulpless teeth restored with conventionally cemented zirconia posts: A pilot study J Prosthet Dent 2006; 95: 311-14. 111. Bittner N, Hill T, Randi A: Evaluation of a one-piece milled zirconia post and core with different post and core systems: an in vitro study J Prosthet Dent 2010; 103: 369-379. 112. Toksavul S, Toman M, Uyulgan B, Schmage P, Nergiz I: Effect of luting agents and reconstruction techniques on the fracture resistance of pre-fabricated post systems. J Oral Rehabil 2005; 32 (6): 433-40. 113. Baba NZ, Golden G, Goodacre CJ: Nonmetallic prefabricate dowels: a review of compositions, properties, laboratory, and clinical test results. J Prosthodont 2009; 18: 527-536. 114. Schwartz RS, Robbins JW: Post placement and restoration of endodontically treated teeth: a literature review. J Endod 2004; 30: 289-301. 115. Spingate S, Winchester L: An evaluation of zirconium oxide brackets: a preliminary laboratory and clinical report Br J of Orthod 1991; 18 (199): 203-209. 116. Keith O, Kusy R, Whitley J: Zirconia brackets: an evaluation of morphology and coefficients of friction. Am J Orthod Dentofacial Orthop 1994; 106 (6): 605-14. 117. Douglass JB: Enamel wear caused by ceramic brackets Am J Orthod Dentofacial Orthop 1989 Feb; 95 (2): 96-8. 118. Gomes A, Montero J: Zirconia implant abutments: a review Med Oral Patol Oral Cir Bucal 2011; 16: e50-55. 119. Andersson B et al: Alumina ceramic implant abutments used for single-tooth replacement: a prospective 1- to 3-year multicenter study Int J Prosthodont 2001; 14 (5): 432-8. 120. Andersson B, Glauser R, Maglione M, Taylor A: Ceramic implant abutments for short-span FPDs: a prospective 5year multicenter study. Int J Prosthodont 2003 Nov-Dec; 16 (6): 640-6. 133 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72. 73. 74. 75. 76. 77. 78. 134 Electrical properties of YSZ films prepared by net shape technology J of the Electrochemical Society 2005; 152 (2): A454-A458. Garcia R, Ussui V, de Lima N, Muccillo E, Lazar D: Physical properties of alumina/yttria-stabilized zirconia composites with improved microstructure Journal of Alloys and Compounds 2009; 486 (1-2): 747-753. Rigney M, Funkenbusch E, Carr P: Physical and chemical characterization of microporous zirconia Journal of Chromatography 1990; 499: 291-304 Wang C, Ong S, Xu P, Chen C: Electrical properties of crystalline YSZ films on silicon as alternative gate dielectrics Semicon Sci Technol 2001; 16: 13-16. Bengisu M: Engineering ceramics Spinger 2007 Badwal S, Drennan J: Grain boundary sensitivity in Y-TZP materials as a function of thermal history J Mater Sci 24 (1989) 88-96. Chen C, Hsiang H, Hsu S: Preparation and characterization of Y-TZP powders coated with alumina Journal of Ceramic Processing Research. 2008; 8: 131-134. Hannink R, Kelly P, Muddle B: Transformation Toughening in Zirconia-Containing Ceramics J Am Ceram Soc, 2000; 83 (3): 461-87. Komine F, Blatz M, Matsumura H: Current status of zirconiabased fixed restorations Journal Oral Science 2010; 52 (4): 531-539. Parker R: Use of zirconia in restorative dentistry Dent Today 2007; 26 (3): 114-112. Al-Amleh B, Lyons K, Swai M: Clinical trials in zirconia: a systematic review J of Oral Rehabil 2010; 37: 641-652. Griggs JA: Recent advances in materials for all-ceramic restorations. Dent Clin North Am 2007; 51 (3): 713-27. Creugers N, Kayser A, Van’t Hoff M: A meta-analysis of durability data on conventional fixed bridges. Community Dent Oral Epidemiol 1994; 22: 448-452. Lucarroti P, Burke F: Analysis of an administrative database of indirect restorations over 11 years Journal of Dentistry 2009; 37: 4-11. Sadan A, Blatz M, Lang B: Clinical considerations for densely sintered alumina and zirconia restorations: part 1 Int J Per Rest Dent 2005; 25: 213-219. Bahhav V, Aras M: Zirconia-based fixed partial dentures: a clinical review Quintessence Int 2011; 42: 173-182. Koutayas S, Vagkopoulou T, Pelekanos S, Koidis P, Strub J: Zirconia in dentistry: Part 2. Evidence-based clinical breakthrough The European Journal of Esthetic dentistry 2009; 4 (2): 348-380. Akbar J, Petrie C, Walker M, Williams K, Eick J: Marginal adaptation of Cerec 3 CAD/CAM composite crowns using two different finish line preparation designs. J Prosthodont 2006; 15 (3): 155-63. McLaren E, Hyo L: CAD/CAM update: technologies and materials and clinical perspectives Inside Dentistry 2006; Nov/Dec: 98-103. Reich S, Petschelt A, Lohbauer U: The effect of finish line preparation and layer thickness on the failure load and fractography of ZrO2 copings. J Prosthet Dent 2008 May; 99 (5): 369-76. Lin M et al: the effect of tooth preparation form on the fit of Procera copings Int J Prosthodont 1998; 11: 580-90. 121. Nakamura K, Kanno T, Milleding P, Ortengren U: Zirconia as a dental implant abutment material: a systematic review Int J Prosthodont. 2010 Jul-Aug; 23 (4): 299-309. 122. Holst S, Blatz MB, Hegenbarth E, Wichmann M, Eitner S: Prosthodontic considerations for predictable singleimplant esthetics in the anterior maxilla. J Oral Maxillofac Surg 2005; 63 (9 Suppl 2): 89-96. 123. Glauser R et al: Experimental zirconia abutments for implant supported single tooth restorations in esthetically demanding regions:4-year results of a prospective clinical study Int J Prosthodont 2004; 17: 285-290. 124. Scarano A, Piattelli M, Caputi S, Favero G, Piattelli A: Bacterial adhesion on commercially pure titanium and zirconium oxide disks: an in vivo human study. J Periodontol 2004; 75 (2): 292-6. 125. Raigrodski AJ, Hillstead MB, Meng KG, Chung KH: Survival and complications of zirconia-based fixed dental prostheses: a systematic review. J Prosthet Dent 2012; 107: 170-7. 126. Fischer J, Grohman P, Stawarczyk B: Effect of zirconia surface treatments on the shear strength of zirconia/veneering ceramic composites. Dent Mater J 2008; 27: 448-54. 127. Hill E, Lott J: A clinically focused discussion of luting materials Australian Dent J 2011; 56 (1 suppl): 67-76. 128. Amaral R, Ozcan M, Valandro L, Balducci I, Bottino M: Effect of conditioning methods on the microtensile bond strength of phosphate monomer-based cement on zirconia ceramic dry and aged conditions J Biomed Res Part B Appl Biomater 2008; 85B: 1-9. 129. Siarampi E, Kontonasaki E, Papadopoulou L, Kantiranis N, Zorba T, Paraskevopoulos KM, Koidis P: Flexural strength and the probability of failure of cold isostatic pressed zirconia core ceramics. J Prosthet Dent 2012; 108 (2): 84-95. 130. Vatali A, Siarampi E, Kontonasaki E, Kantiranis N, Zorba T, Vouroutzis N, Paraskevopoulos KM, Koidis P: Effect of In Vitro Ageing on a Cold Isostatic-Pressed Zirconia Ceramic for All Ceramic Restorations. Key Engineer Mater 2012; 493-494: 604-608. Corresponding author: E. Tzanakakis e-mail: [email protected] e.n.: The clinical work described in this paper is performed by the authors. Authors declare no financial interest whatsoever on dental products and companies mentioned in this article. Hellenic Stomatological Review 57: 101-137, 2013 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review 79. Conrad H, Seong W, Pesun I: current ceramc materials and systems with clinical recommendations: A systematic review J Prosthet Dent 2007; 98: 389-404. 80. Pogoncheff C, Duff R: Use of zirconia collar to prevent interproximal porcelain fracture: a clinical report J Prosthet Dent 2010; 104: 77-79. 81. Tinschert J et al: Clinical behavior of zirconia-based fixed partial dentures made of DC-Zirkon: 3 years results Int J Prosthodont 2008; 21: 217-222. 82. Sailer I, Gottner J, Kanel S, Hammerle C: Randomized controlled clinical trial of zirconia-ceramic and metalceramic posterior FPDs. A 3-year follow up Int J Prosthodont 2009; 22: 553-560. 83. Beuer F, Edelhoff D, Gernet W, Sorensen J: Three-year clinical prospective evaluation of zirconia-based posterior fixed dental prostheses Clin Oral Invest 2009; 13: 445-451. 84. Cehreli M, Kokat A, Akca K: CAD/CAM Zirconia Vs. slip-cast glass-infiltrated alumina/zirconia all-ceramic crowns: 2year results of a randomized controlled clinical trial J Appl Oral Sci 2009; 17 (1): 49-55. ’ 85. Suarez M, Lozano J, Paz Salido M, Mart›nez F: Three-year clinical evaluation of In-Ceram Zirconia posterior FPDs The International Journal of Prosthodontics 2004; 17 (1): 35-8. 86. Ozkurt Z, Kazazoglu E: Clinical success of zirconia in dental applications J of Prosthodont 2010; 19: 64-68. 87. Carracho J, Razoog M: Removable partial denture abutments restored with all-ceramic surveyed crowns Quintessence Int 2006; 37: 283-288. 88. Pellechia R, Kang K, Hirayama H: Fixed partial denture supported by all-ceramic copings: a clinical report J Prosthet Dent 2004; 92: 220-3. 89. Chevalier J, Cales B, Drouin J: Low-temperature aging of YTZP ceramics J Am Ceram Soc 1999; 82: 2150-2154. 90. Larsson C et al: Fracture strength of four unit YTZP FPD cores designed with varying connector diameter. An in vitro study J Oral Rehab 2007; 34: 702-709. 91. Sundh A, Molin M, Sjogren G: Fracture resistance of yttrium oxide partially stabilized zirconia all-ceramic bridges after veneering and mechanical fatigue testing Dental Materials 2005; 21: 476-482. 92. Vult von Steyern P: All-ceramic fixed partial dentures. Studies on aluminum oxide- and zirconium dioxide-based ceramic systems. Swed Dent J Suppl 2005; (173) : 1-69. 93. Kamposiora P, Papavasiliou G, Bayne S, Felton D: Stress concentration in all-ceramic posterior fixed partial dentures Quintessence Int 1996; 27: 701-706. 94. Studart R, Filser F, Kocher P, Gauckler L: Fatigue of zirconia under cyclic loading in water and its implications for the design of dental bridges. Dent Mater 2007; 23 (1): 106-14. 95. Guazzato M, Albakry M, Swain M, Ironside J: Mechanical properties of In-Ceram alumina and In-ceram Zirconia Int J Prostodont 2002; 15: 339-346. 96. Schmitt J et al: Zirconia posterior fixed partial dentures: A prospective clinical 3-year follow up Int J Prosthodont 2009; 22: 597-603. 97. Bicaro L, Bonfiglioli R, Soattin M, Vigolo P: An in vivo evaluation of fit ofzirconium-oxide based ceramic single crowns, generated with two CAD/CAM systems, in comparison to metal ceramic single crowns. J Prosthodont 2013; 22: 36-41. 98. Komine F, Gerds T, Witkowski S, Strub J: Influence of framework configuration on the marginal adaptation of zirconium dioxide ceramic anterior four-unit frameworks. Acta Odontol Scand 2005; 63: 361-6. Hellenic Stomatological Review 57: 101-137, 2013 135 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review 99. Bindl A, Mormann W: Marginal and internal fit of all-ceramic CAD/CAM crown-copings on chamfer preparations J of Oral Rehab 2005; 32: 441-447. 100. Att W et al: Marginal adaptation of three different zirconium dioxide three unit fixed dental prostheses J Prosthet Dent 2009; 101: 239-247. 101. Mehl C, Ludwig K, Steiner M, Kern M: Fracture strength of prefabricated all-ceramic inlay-retained fixed dental prostheses Dental Materials 2010; 26: 67-75. 102. Edelhoff D, Sorensen J: Tooth structure removal associated with various preparation designs for posterior teeth. J Prosthet Dent 2002; 22: 241-9. 103. Abou Tara M, Eschbach S, Wolfart S, Kern M: Zirconia ceramic inlay-retained fixed dental prostheses - first clinical results with a new design J Dent 2011 Mar; 39 (3): 208-11. 104. Wolfart S, Ludwig K, Uphaus A, Kern M: fracture strength of all ceramic posterior inlay retained fixed partial dentures Dental Materials 2007; 23: 1513-1520. 105. Wolfart S, Bohlsen F, Wegner SK, Kern M: A prospective evaluation up to five years of all ceramic crown and inlay retained FPDs Int J Prosthodont 2005; 18: 497-505. 106. Rossentritt M et al: Zirconia resin-bonded fixed partial dentures in the anterior maxilla Quintessence Int 2008; 39: 313-319. 107. Walker Effect of simulated resin-bonded fixed partial denture clinical conditions on resin cement mechanical properties Journal of Oral Rehabilitation 2003; 30: 837-846. 108. Duarte S: et al Resin Bonded fixed partial dentures with a new modified zirconia surface: a clinical report J Prosthet Dent 2009; 102: 68-73. 109. Bergman B, Lundquist P, Sjögren U, Sundquist G: Restorative and endodontic results after treatment with cast posts and cores J Prosthet Dent 1989; 61 (1): 10-5. 110. Nothdurft F, Pospiech P: Clinical evaluation of pulpless teeth restored with conventionally cemented zirconia posts: A pilot study J Prosthet Dent 2006; 95: 311-14. 111. Bittner N, Hill T, Randi A: Evaluation of a one-piece milled zirconia post and core with different post and core systems: an in vitro study J Prosthet Dent 2010; 103: 369-379. 112. Toksavul S, Toman M, Uyulgan B, Schmage P, Nergiz I: Effect of luting agents and reconstruction techniques on the fracture resistance of pre-fabricated post systems. J Oral Rehabil 2005; 32 (6): 433-40. 113. Baba NZ, Golden G, Goodacre CJ: Nonmetallic prefabricate dowels: a review of compositions, properties, laboratory, and clinical test results. J Prosthodont 2009; 18: 527-536. 114. Schwartz RS, Robbins JW: Post placement and restoration of endodontically treated teeth: a literature review. J Endod 2004; 30: 289-301. 115. Spingate S, Winchester L: An evaluation of zirconium oxide brackets: a preliminary laboratory and clinical report Br J of Orthod 1991; 18 (199): 203-209. 116. Keith O, Kusy R, Whitley J: Zirconia brackets: an evaluation of morphology and coefficients of friction. Am J Orthod Dentofacial Orthop 1994; 106 (6): 605-14. 117. Douglass JB: Enamel wear caused by ceramic brackets Am J Orthod Dentofacial Orthop 1989 Feb; 95 (2): 96-8. 118. Gomes A, Montero J: Zirconia implant abutments: a review Med Oral Patol Oral Cir Bucal 2011; 16: e50-55. 119. Andersson B et al: Alumina ceramic implant abutments used for single-tooth replacement: a prospective 1- to 3-year multicenter study Int J Prosthodont 2001; 14 (5): 432-8. 120. Andersson B, Glauser R, Maglione M, Taylor A: Ceramic implant abutments for short-span FPDs: a prospective 5year multicenter study. Int J Prosthodont. 2003 Nov-Dec; 16 (6): 640-6. 136 Hellenic Stomatological Review 57: 101-137, 2013 μÈ‚ÏÈÔÁÚ·ÊÈ΋ ∞Ó·ÛÎfiËÛË Literature Review 121. Nakamura K, Kanno T, Milleding P, Ortengren U: Zirconia as a dental implant abutment material: a systematic review Int J Prosthodont 2010 Jul-Aug; 23 (4): 299-309. 122. Holst S, Blatz MB, Hegenbarth E, Wichmann M, Eitner S: Prosthodontic considerations for predictable singleimplant esthetics in the anterior maxilla. J Oral Maxillofac Surg 2005; 63 (9 Suppl 2): 89-96. 123. Glauser R et al: Experimental zirconia abutments for implant supported single tooth restorations in esthetically demanding regions:4-year results of a prospective clinical study Int J Prosthodont 2004; 17: 285-290. 124. Scarano A, Piattelli M, Caputi S, Favero G, Piattelli A: Bacterial adhesion on commercially pure titanium and zirconium oxide disks: an in vivo human study. J Periodontol 2004; 75 (2): 292-6. 125. Raigrodski AJ, Hillstead MB, Meng KG, Chung KH: Survival and complications of zirconia-based fixed dental prostheses: a systematic review. J Prosthet Dent 2012; 107: 170-7. 126. Fischer J, Grohman P, Stawarczyk B: Effect of zirconia surface treatments on the shear strength of zirconia /veneering ceramic composites. Dent Mater J 2008; 27: 448-54. 127. Hill E, Lott J: A clinically focused discussion of luting materials Australian Dent J 2011; 56: (1 suppl): 67-76. 128. Amaral R, Ozcan M, Valandro L, Balducci I, Bottino M: Effect of conditioning methods on the microtensile bond strength of phosphate monomer-based cement on zirconia ceramic dry and aged conditions J Biomed Res PartB Appl Biomater 2008; 85 B: 1-9. 129. Siarampi E, Kontonasaki E, Papadopoulou L, Kantiranis N, Zorba T, Paraskevopoulos KM, Koidis P: Flexural strength and the probability of failure of cold isostatic pressed zirconia core ceramics. J Prosthet Dent 2012; 108 (2): 84-95. 130. Vatali A, Siarampi E, Kontonasaki E, Kantiranis N, Zorba T, Vouroutzis N, Paraskevopoulos KM, Koidis P: Effect of In Vitro Ageing on a Cold Isostatic-Pressed Zirconia Ceramic for All Ceramic Restorations. Key Engineer Mater 2012; 493-494 : 604-608. ¢È‡ı˘ÓÛË ÁÈ· ÂÈÎÔÈÓˆÓ›·: E. T˙·Ó·Î¿Î˘ e-mail: [email protected] I‰È·›ÙÂÚ˜ ¢¯·ÚÈÛٛ˜ ÛÙËÓ Ù. ‰È¢ı‡ÓÙÚÈ· ÙÔ˘ K¤ÓÙÚÔ˘ EÚ‡Ó˘ ÂÏÏËÓÈ΋˜ ÁÏÒÛÛ·˜ Ù˘ Aη‰ËÌ›·˜ AıËÓÒÓ Î. °È·ÎÔ˘Ì¿ÎË EÏ¢ıÂÚ›· ÁÈ· ÙË ÁψÛÛÈ΋ ÂÈ̤ÏÂÈ· ÙÔ˘ ÂÏÏËÓÈÎÔ‡ ÎÂÈ̤ÓÔ˘ Î·È ÛÙÔ˘˜ Ô‰ÔÓÙÔÙ¯ӛÙ˜ Î. ¶··‰¿ÎË °. Î·È NÈÎÔÏÔ‡‰È· N. ÁÈ· ÙË Û˘ÓÂÚÁ·Û›· ÙÔ˘˜. Û.Û.: H ÎÏÈÓÈ΋ ÂÚÁ·Û›· Ô˘ ÂÚÈÁÚ¿ÊÂÙ·È ÛÙÔ ¿ÚıÚÔ ·˘Ùfi ¤¯ÂÈ Ú·ÁÌ·ÙÔÔÈËı› ·fi ÙÔ˘˜ Û˘ÁÁÚ·Ê›˜. OÈ Û˘ÁÁÚ·Ê›˜ ‰ËÏÒÓÔ˘Ó fiÙÈ ‰ÂÓ ¤¯Ô˘Ó ηӤӷ ÔÈÎÔÓÔÌÈÎfi fiÊÂÏÔ˜ ·fi ÙË ¯Ú‹ÛË Î·È ÂÚÈÁÚ·Ê‹ ˘ÏÈÎÒÓ, ‚ÔËıËÙÈÎÒÓ Ì¤ÛˆÓ Î·È ÂÙ·ÈÚÂÈÒÓ ÛÙÔ ¿ÚıÚÔ ·˘Ùfi. Hellenic Stomatological Review 57: 101-137, 2013 137
Scarica
