Author/Editor		Cotič, Jasna; Kocjan, Andraž; Panchevska, Sanja; Kosmač, Tomaž; Jevnikar, Peter
Title		In vivo aging of zirconia dental ceramics - part II
Type		članek
Publication year		2020
Volume		str. str.
ISSN		0109-5641 - Dental materials : official publication of the Academy of Dental Materials
Language		eng
Abstract		Objective 3Y-TZP ceramics with reduced alumina content have improved translucency and are used in monolithic dental restorations without porcelain-based veneers. The workflow can be further streamlined with rapid sintering. This study was designed to assess how these approaches affect ageing when the materials are exposed to the oral environment in vivo. Methods 43 discs were fabricated from 3Y-TZP powder with 0.05% Al2O3 and sintered with conventional or rapid regimens (1450 °C 2 h, 1530 °C 2 h, or 1530 °C 25 min). Their surfaces were polished or airborne-particle abraded with 50 %m Al2O3. The discs were incorporated in complete dentures of 16 volunteers and worn continuously for up to 48 months. Ageing changes on disc surfaces were monitored every 6 months by X-ray diffraction, scanning electron microscopy and atomic force microscopy. Data was statistically analysed with linear models. Results The amount of monoclinic phase on polished surfaces increased linearly, reaching up to 40% after 48 months in vivo. The ageing process observed for rapid sintering was 1.6 times faster compared to conventional sintering. A nano-scale increase in roughness with microcracking was also detected on polished surfaces. Airborne-particle abraded surfaces did not exhibit clear signs of ageing during the course of the study. Significance Highly-translucent 3Y-TZP ceramics are more susceptible to ageing than classic 3Y-TZP. After 4 years in vivo, the extent of degradation did not yet constitute grounds for clinical concern, but was more pronounced in materials prepared with rapid sintering.
Keywords		3Y-TZP ceramics low-temperature degradation high translucency 3Y-TZP keramika razgradnja pri nizkih temperaturah visoka prosojnost