Surface roughness of light-activated glass-ionomer cement restorative materials after finishing

The purpose of this study was to compare the effect of various finishing sequences on the surface roughness of four new light-activated (LAGIC) restorative materials. Restorative materials included a polyacid-modified composite resin (Variglass VLC) and three resin-modified glass-ionomer cements (Vitremer, Photac-fil, and Fuji II LC). Thirty specimens of each material were prepared in Macor dies and randomly divided into six finishing sequence groups (n=5): (1) Mylar strip (control), (2) carbide bur/Sof-Lex XT disks, (3) ET finishing diamonds, (4) carbide bur/Enhance polishing system, (5) carbide bur/ Politip rubber finishers, and (6) carbide bur alone. Average surface roughness (R_a) in micrometers was measured with a Mitutoyo Surftest 401 Surface Roughness Tester and the data compared using ANOVA, Student-Newman-Keuls Multiple Comparison tests, and Dunnett's test at P ≤ 0.05. Surface topography was also assessed using the scanning electron microscope (SEM) on epoxy replicas from samples of each group. The Mylar strip produced the smoothest surface and finishing sequences; (2) and (3) were significantly smoother than (4), (5), and (6). There were no significant differences between restorative materials when all finishing sequences were combined. SEM analysis was consistent with the profilometer results. Materials with higher (R_a) values appeared to have rougher surfaces. Rubber abrasives and polishing pastes seem to preferentially remove the polysalt and resin matrix of these materials.