Surface Roughness Characterization of Current Tooth Colored Filling Materials After Tooth Brushing: An AFM Study

Objectives: Directly placed filling materials have a profound influence on the surface roughness of tooth-coloured restorations. This in vitro study is designed to evaluate the influence of tooth brushing on surface roughness of three different current composite resins and glass ionomer cement.
Methods: Eighteen specimens of the restorative materials, nanofilled composite Filtex Z350 XT, the sub-micron composite Estelite Sigma Quick, and nanofilled glass ionomer Ketac N100 were used. Six specimens (2 mm thick and 6 mm in diameter) of each tested material prepared according to the manufacturer's directions. After insertion of the test material, poly Ethylene was applied and the material pressed down with glass slide, obtaining flat surfaces. All samples were then polished using Sof-Lex discs from coarse (55 µm) to medium (40 µm) to fine (24 µm), and ultrafine (8 µm), using a mandrel and a slow-speed hand piece. After polishing, the samples were cleaned ultrasonically using a Sonica 2200 ETH for 5 minutes and then stored in distilled water at 37° C for 24 hours. A brushing sequence of 5000, 10,000 and 20,000 cycles was performed for all the samples. An AFM examination was used to determine average surface roughness (Ra) of the material assessed. The data obtained were analyzed using one-way ANOVAs and post-hoc comparison tests.
Results: Brushing significantly increased roughness (Ra) for all tooth colored filling materials. Statistical significance was declared if the P value was ≤ 0.05. After 5000, 10,000 and 20,000 cycles, Ketac N 100 nano ionomer demonstrated significantly higher surface roughness than the other materials, followed by Estelite Sigma Quick. Filtex Z350 XT showed the lowest value of surface roughness. Surface roughness was increased with each cycle for three materials.
Conclusions: Although the initial performance of three materials was similar, a greater number of brushing cycles generated surface roughness of the materials.