Influence of Different Finishing-Polishing Procedures and Thermocycle Aging on the Surface Roughness of Nano-Ceramic Hybrid CAD/CAM Material

Aim: The aim of this study was to evaluate the effectiveness of different finishing-polishing (FP) procedures on reducing surface roughness of nanoceramic hybrid CAD/CAM material before and after thermocycle (TMC) aging. Materials and Methods: Nano-ceramic hybrid CAD/CAM specimens were subjected to 8 different (2-glaze and 6-mechanical) FP procedures as follows (n=20): 1. Optiglaze (OG) 2. Diamond glaze (DG), 3. Vita Enamic Polishing Set (VE), 4. VE+Gradia Diapolisher paste (VE-G) 5. VE+Super-Snap SuperBuff (VE-S) 6. Sof-Lex Disc kit (SL) 7. SL+Gradia Diapolisher paste (SLG) 8. SL+Super-Snap SuperBuff (SL-S). Surface roughness of each specimen was measured by using a contact profilometer. All specimens were artificially aged with TMC (5000 cycles, 5 & DEG;C/55 & DEG;C) and surface roughness measurements were repeated. One extra specimen from each group before and after TMC was examined with SEM. Surface roughness data were analyzed by repeated measures ANOVA, dependent t-test and Tukey test. Results: Significantly higher mean Ra values were found for groups OG and DG compared to other groups (P<0.05). Differences between glaze groups and differences between mechanical FP groups were not significant (P>0.05). Groups SL-S and DG demonstrated comparable results before and after TMC (P>0.05). SEM analysis revealed that surfaces of VE-S and SL-S groups were smooth and free of scratches. Conclusions: Mechanical FP procedures were more effective in reducing surface roughness of nanoceramic hybrid CAD/CAM material than glaze applications. Sof-Lex kit followed by Super-Snap SuperBuff disc application can be recommended as the mechanical FP procedure of choice considering that this method provided smooth surfaces that were maintained after TMC.