Effect of three bleaching agents on the surface properties of three different esthetic restorative materials

Statement of problem. Information related to the effect of night-guard vital bleaching procedure on the surface properties of esthetic dental restorative materials is incomplete. Purpose. The aim of this study was to examine the effects of 3 proprietary carbamide peroxide bleaching agents on the surface properties of 3 dental esthetic restorative materials. Material and methods. Three bleaching products (Nite White, Opalescence, and Rembrandt Lighten Gel) and 3 restorative materials (Duceram, Fuji II LC, and Silux Plus) were studied. A stainless steel mold and a 6-mm-thick polytetrafluoroethylene plate with a 1-cm-diameter hole were used to prepare 30 standardized specimens for each of the 3 restorative materials tested. Each group was divided into 3 subgroups (n=10). Two specimens from each subgroup were selected to form a control group. Three different carbamide peroxide bleaching agents were applied to each restorative material group for 8 hours per day for 30 days, respectively. Initial roughness measurements (Ra measured in mum) were made by use of a profilometer, at repeated intervals of 24 hours, 48 hours, 1, 2, 3, and 4 weeks (30 days). Surface topography of the specimens was assessed by scanning electron microscopy, and results were compared with the control group graphically. Surface structure and alterations of atomic weight percentages of element were made by use of energy-dispersive x-ray microanalysis. One-way analysis of variance was used to evaluate the surface roughness measurements. Significant results were evaluated with Fisher and Duncan's multiple range test (P.005)