Effects of surface treatments on the translucency, opalescence, and surface texture of dental monolithic zirconia ceramics

Abstract

STATEMENT OF PROBLEM: Surface polishing or glazing may increase the appearance of depth of monolithic zirconia restorations. PURPOSE: The purpose of this in vitro study was to investigate the effects of surface treatments on the translucency, opalescence, and surface texture of dental monolithic zirconia ceramics. MATERIAL AND METHODS: Forty-five monolithic zirconia specimens (16.3x16.4x2.0 mm) were divided into groups I to V, according to the number of colorings each received. Each group was then divided into 3 subgroups (n=3) according to the surface treatment: N=no treatment: P=polished: and G=glazed. CIElab color coordinates were obtained relative to D65 on a reflection spectrophotometer. The translucency parameter (TP) and opalescence parameter (OP) were calculated. One specimen per subgroups I and V was selected for evaluation of surface roughness (Ra) and was examined with scanning electron microscopy (SEM). Data were analyzed with 2-way ANOVA and pairwise comparisons (alpha=.05). Statistical powers were verified to evaluate results (alpha=.05). RESULTS: The interaction effects of surface treatments combined with the number of colorings were significant for TP, OP, and Ra (P<.001), as follows: Ra=partial eta squared [etap(2)]=.928: OP etap(2)=.184: and TP etap(2)=.144. No significant differences between TP were found among surface treatments in most groups (P>.05), whereas glazing significantly decreased OP and Ra in most groups. SEM images demonstrated that surface treatments affected the surface texture of monolithic zirconia ceramics. CONCLUSIONS: Surface treatments combined with coloring strongly affect the surface texture of dental monolithic zirconia ceramics.