The Effect of Thickness And Accelerated Aging on Opalescence of Different Ceramic Materials

Purpose: The objective of the study was to evaluate the effect of ceramic material type and thickness on opalescence before and after accelerated aging. Materials and methods: 180 all-ceramic slices were divided into three groups (n=60) according to the ceramic material (InCoris TZI, Empress CAD HT, and Empress CAD LT). Each group was further subdivided into four subgroups (n = 15) according to their thickness (0.5 mm, 0.8 mm, 1 mm and 1.2 mm).). CIE Lab coordinates were measured for each slice against black and white backgrounds using intraoral spectrophotometer and OP was calculated. All specimens were subjected to accelerated aging using autoclave (134 ºC, 0.2 MPa for 5 h) and OP was calculated after accelerated aging. Repeated ANOVA combined with a Tukey-post hoc test were used to analyze the data obtained (P ≤ 0.05). Results: The results showed that ceramic material type and thickness have significant effect on opalescence with OP values (from 4.4±1.2 to 7.1±1.7) for InCoris TZI, (from 4.1±0.28 to 5.7±0.36) for CAD HT, and (from 5.9±0.7 to 8.7±4.6) for CAD LT, while the effect of accelerated aging was not statistically significant. Conclusion: The dental ceramic type affected the opalescence with Empress CAD HT showing the highest OP values. Increasing the thickness caused an increase in the opalescence of leucite reinforced glass ceramic, while it decreased the opalescence of zirconia. Therefore, manufactures should develop all-ceramic materials that can simulate the opalescence of natural teeth especially in esthetic ceramic restoration with lower thickness