Study on the wear resistance of the surface sealing layer with flowable composite resin on the enamel bonded with bracket

Abstract

Objective To study the wear resistance of the layer of the surface sealing with flowable composite resin and the surface sealing improve the wear resistance of the enamel bonded with bracket. Methods Forty extracted premolars were chosen for the study. They were divided into four groups, ten premolars in each group: undemineralizing group, self-etching group, direct demineralizing group, demineralizing after surface sealing group. The teeth in the later two groups were demineralized by 0.1M lactic acid gelatin for 48h after thermostat water bathing and thermocycling.The microstructure of the buccal surface of the enamel and the change of the surface sealing layer were observed through scanning electron microscope after the toothbrush wear testing 31,000 times.Results After wearing, the brush mark couldn't be seen in the undemineralizing group. The brush mark was deeper in the self-etching group and the direct demineralizing group. In the demineralizing after surface sealing group, the layer of surface sealing with flowable composite resin was still on the buccal surface of the sealed teeth. The average thickness of the layer of the flowable composite resin was 167.58±6.38μm、140.93±7.88μm between before and after wear. The average wear quantity was 26.85±4.48μm. After the paired samples T test, the thickness of the layer of the flowable composite resin between before and after wear revealed statistically significant differences. Conclusion Demineralization decreases the wear resistance of the enamel bonded with bracket. Some flowable composite resin was removed after wear, but the layer of surface sealing with flowable composite resin was still on the buccal surface of the sealed tooth to improve the wear resistance of the enamel bonded with bracket. Key words: Surface sealing; Flowable composite resin; Wear; Fixed orthodontics