Abstract:
Objectives:
The aim of this study is to evaluate the impact of thermocycling on the optical properties and surface roughness of conventional lithium disilicate and zirconia reinforced lithium disilicate heat-pressed glass ceramics.
Materials and Methods:
Eighteen samples (a diameter of 12 mm and 1.5 mm thickness) were fabricated from three types of heat-pressed ceramic: a conventional lithium disilicate heat-pressed glass-ceramic (IPS e.max Press, Ivoclar Vivadent, Germany) (n=6), and 2 heat-pressed zirconia reinforced lithium silicate press glass-ceramic, Celtra Press(Dentsply, Germany) (n=6) and Ambria Press (Vita-Zahnfabrik, Germany) (n=6). Specimen were finished and polished carefully and then glazed according to the manufacturers' instructions. The discs were assessed for their translucency, color change and surface roughness before and after thermocycling using distilled water with baths of 5 and 55 ◦C, for 10,000 cycles. Results were analyzed using one-way ANOVA (α=0.05)
Results:
For all pressed ceramics, thermocycling resulted in significant decrease in the translucency parameter (p<0.001). Vita Ambria and IPS e.max Press showed the highest significant ΔL compared to Celtra Press (p<0.001). For the ΔE, Vita Ambria showed the highest ΔE values compared to Celtra Press and IPS e.max Press. For all pressed ceramics, a significant increase in surface roughness resulted after thermocycling at p<0.001.
Conclusions:
Vita Ambria Pressed ceramic is significantly more translucent than all the other tested groups before and after thermocycling. The color and translucency of tested ceramics were affected by thermocycling but still considered clinically accepted. Thermocycling significantly increased the surface roughness of all the tested ceramic materials.