Gloss retention of nanocomposite resins after manual and electric toothbrushing

Abstract

[한글]

[영문]Gloss is a characteristic of visual appearance that originates from the geometrical distribution of light reflected by the surface and is related to the surface roughness. Surface gloss is affected by finishing, polishing procedure and filler type, shape of composite resin. Toothbrushing roughens the surface of most composite materials and lowers the gloss in oral environment. The purpose of this study was to evaluate the change of gloss for nanocomposite resins by toothbrushing and effect of toothbrush type on gloss.Composite resins used in this study were Gradia Direct, Filtek Z250 (microhybrid), Heliomolar (microfill), Ceram X Duo, Synergy D6, Tetric Evoceram, Tetric N-ceram, Premisa (nanohybrid) and Filtek Supreme (nanofill). Composite resin was filled into acrylic resin mold and light cured. Unpolished composite resins were used as control and specimens were polished with Enhance® and Pogo® (Dentsply/Caulk, Milford, DE, USA) as baseline. 10 specimens were made for each group. 3 different toothbrushing groups (manual, rotating-oscillating and sonic toothbrushing) were simulated. For manual toothbrushing, V-8 cross brushing machine was used and 2 electric toothbrushing machines were customized. Braun oral B® Indicator Plus, Professional Care 8500 DLX, Sonic complete were used and each brushing force was 250g, 150g and 120g respectively. In this study, six months of toothbrushing was investigated and gloss was measured using Novo-curveTM glossmeter (Rhopoint, U.K.). Scanning electron microscope (S-3000N, HITACHI, Japan) was used to evaluate qualitatively the change of surface. The results were analyzed by two-way analysis of variance (ANOVA) and Tukey’s t-test (α≤0.05) and linear regression with control of baseline was used for evaluating the interaction of composite resin and toothbrushing method. After manual toothbrushing, Filtek Supreme showed the

highest gloss retention followed by Premisa and Heliomolar. Ceram X Duo and Filtek Z250 showed the lowest gloss retention. After rotating-oscillating toothbrushing, Filtek Supreme, Premisa and Heliomolar showed high gloss retention. After sonic toothbrushing, Filtek Supreme showed the highest gloss retention followed by Premisa, Heliomolar, Gradia Direct and Tetric Evoceram. Comparing the gloss retention for 3 toothbrushing methods (for all composite resins together), sonic toothbrushing produced higher gloss retention than rotating-oscillating toothbrushing. Overall, Filtek Supreme, Premisa and Heliomolar showed high gloss retention for all 3 toothbrushings and had smooth surfaces in SEM images. Filtek Z250 and Ceram X Duo showed low gloss retention for all 3 toothbrushings and Gradia Direct, Synergy D6, Tetric Evoceram and Tetric N-ceram showed moderate gloss retention having some difference in order according to toothbrushing method.