Abstract
BACKGROUND: This in vitro study aims to evaluate the effects of two different surface finishing procedures-glazing and polishing-on the stability of colour, the translucency, and the roughness of surface with three CAD/CAM ceramic materials: lithium disilicate ceramic (LDC), zirconia-reinforced lithium silicate ceramic (ZLC), and translucent zirconia (TrZ). The process is evaluated before and after coffee thermocycling. METHOD: A total of 120 samples (1.0 ± 0.1 mm) were prepared from LDC (IPS e.max CAD HT A2), ZLC (Celtra Duo HT A2), and TrZ (Cercon HT A2). All samples were subjected to standardized grinding for 20 s to simulate chairside adjustments and were then assigned to glaze (G) or polish (P) subgroups (n = 20). Surface roughness (Ra, Rz) was measured by using a contact profilometer, while colour coordinates (L*, a*, b*), colour difference (ΔE₀₀) (∆E00), and translucency parameter (TP) were recorded with a colorimeter. All samples underwent 10,000 coffee thermocycles (5–55 °C). Data were analysed by using one-way ANOVA, repeated-measures ANOVA, Kruskal–Wallis, and appropriate post-hoc tests (α = 0.05). RESULT: It is seen that grinding produced the highest Ra and Rz values in ZLC, followed by LDC and TrZ. When surface treatments were completed, polished TrZ showed a significantly lower Ra compared with glazed TrZ, while ZLC and LDC exhibited lower roughness after glazing, although not significantly. Only the ZLC-P group demonstrated a perceptible colour change, yet all groups remained within the clinically acceptable threshold (< 2.23). Before and after thermocycling, LDC showed the highest TP values, followed by ZLC and TrZ. Thermocycling significantly increased Ra (except in TrZ-P and ZLC-P) and decreased TP values in all materials except LDC-P. CONCLUSION: Based on the results, it is concluded that surface finishing techniques and coffee thermocycling affect the optical and surface properties of CAD/CAM ceramics. Glazing generally provides smoother surfaces for glass-ceramics, whereas polishing has superior outcomes for translucent zirconia.