Effect of Finishing Techniques on Surface Characteristics of All-Ceramic Materials

Objectives: All-ceramic dental materials are becoming the first choice of restorative materials because of their superior biocompatibility and distinct aesthetic quality. Their ability to yield relatively smooth surfaces which minimizes plaque deposition and inflammation is another reason for preferance of ceramics. Therefore, the degree of surface roughness of dental ceramics and its effect on biocompatibility has been widely studied. Some additional treatments and polishing procedures may be applied before glazing to reduce surface roughness. The aim of this study was to investigate the effect of various surface finishing techniques on the surface characteristics of different types of all-ceramic dental materials and to determine the final surface quality after glazing. Methods: Finesse (Dentsply), Empress 2 (Ivoclar), In-Ceram alumina (Vita), Cercon (DCS-Precident) all-ceramic systems were selected for the study; Twenty disc-shaped specimens (10mm in diameter, 4mm thick) were fabricated for each ceramic system. Each ceramic group were divided into 4 subgroups (A, B, C, D). The ceramic surfaces were finished with a fine diamond bur in subgroup-A, with stone in subgroup-B, with abrasive sheets in subgroup-C and with rubber in subgroup-D (All-Ceramic Finishing-Polishing Kit, Shofu) before glazing. Scanning electron microscopy (Philips XL 30S-FEG) and atomic force microscopy (MMAFM 2/1700 XL, Veeco) analysis were carried out before and after glazing to quantitatively determine the surface roughness(Ra) values. The data were analysed using one-way Anova and Tukey's multiple comparison tests. Results: The results show that various surface finishing techniques cause significiantly different Ra values between all-ceramic groups before glazing (p<0.05). Finishing with diamond bur gave highest surface roughness values (283.49±70.72 nm) while rubber gave lowest (156.76±44.07 nm). Glazing decreased the surface roughness values (mean 5±2.97 nm) significiantly in all groups (p<0.05). Conclusion: The results conclusively show that proper finishing procedures should be selected peculiar to the dental restorative material to get higher surface quality.