ROUGHNESS OF GLASS-CERAMIC INSERT/COMPOSITE RESIN AFTER POLISHING
The purpose of this study was to compare the effectiveness of three clinically used polishing methods on the surface of Beta-Quartz insert/composite restorations. Thirty composite resin with embedded insert specimens were prepared in bakelite dies and randomly divided into three groups (n=10). Specimens in each group were polished by one of the following methods: (A) diamond abrasive finishing burs (45, 25, 10 micron grit), (B) diamond abrasive finishing burs followed by resin impregnated disks and a 1 micron grit aluminum oxide polishing abrasive paste, and (C) diamond abrasive finishing burs followed by < 1 micron grit diamond polishing paste. The surface roughness, as determined by measuring the average roughness (Ra), and the maximum roughness (Rmax) was determined using a surface profilometer. The Ra of the insert and composite for each system were compared using a paired t-test. Only technique (C) resulted in a statistically similar smoothness of insert and composite. A comparison and ranking of insert and composite Ra for the three methods was done using an ANOVA and Newman-Keuls multiple comparison at a significance level of p<0.05. No significant differences were found in insert or composite smoothness between the three finishing methods. A comparison of the composite/insert interface (Rmax) was made and no significant differences were found among the methods. Clinically, all three polishing methods would result in the same level of surface finish.