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. ClElab 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 [eta(2)(P)]=.928; OP eta(2)(P)=.184; and TP eta(2)(P):=.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.