Effect of polishing and finishing procedures on the surface integrity of restorative ceramics

Purpose: To investigate the effect of surface polishing and finishing methods on the surface roughness of restorative ceramics. Methods: Disk specimens were prepared from feldspar-based, lithium disilicate-based, fluorapatite leucite-based and zirconia ceramics. Four kinds of surface polishing/finishing methods evaluated were: Group 1: Control: carborundum points (CP); Group 2: silicon points (SP); Group 3: diamond paste (DP); Group 4: glazing (GZ). Surface roughness was measured using an interferometer and the parameters of Sa (average height deviation of the surface) and St (maximum peak-to-valley height of the surface) were evaluated. Data were statistically analyzed using two-way ANOVA (P< 0.05) followed by post-hoc test. The mean values were also compared by Student's t-test. Specimen surfaces were evaluated by 3-D images using an interferometer. Results: The zirconia showed the least surface roughness (Sa and St) values after grinding with carborundum points. The significantly lowest Sa values and St values were obtained for lithium disilicate and zirconia ceramics surfaces finished with DP and GZ. The fluorapatite leucite ceramic showed significantly reduced Sa and St values from DP to GZ. The feldspathic porcelain showed the highest surface roughness values among all types of ceramics after all of the polishing/finishing procedures.