Comparative Study On The Surface Wearing Property And The Adhesion Of Streptococcus Mutans On Both Titanium Porcelain And Polymer-Ceramic

Object The study is to evaluate and compare the wear of the titanium porcelain, polymer-ceramic and human enamel, and the adhesion of streptococcus mutans (S. mutans) to the three materials. It is expected to make a progress of the study of polymer-ceramic restoration, and to guide the choice of clinical dental restoration materials.Methods The experimental groups were divided into six groups, including the porcelain group before wearing, the polymer-ceramic group before wearing, the natural enamel before wearing, the porcelain group after wearing, the polymer-ceramic group after wearing and the natural enamel after wearing. The specimens of titanium porcelain and polymer-ceramic are made with clinical standards, and the natural enamel specimens are cleaned by ultrasonic scaling. And all the specimens are polished with special methods. Measure the Vickers hardness and observe the surface morphology with scanning electron microscope (SEM) of all the materials before and after wearing. Then all the materials of the six groups were separately put into culture medium with S. mutans incubated in static condition for48h. The adhesive microbial amount was determined by the colony forming unit counting (CFU) method.Results1、The Vickers hardness (kg/s):porcelain (633.33±25.56)> enamel (295±6.91)> polymer-ceramic(130±1.18);2、The percentage of volume reduction:polymer-ceramic (1.92%±2.70E-4)>enamel (0.94%±1.31E-4)>porcelain (0.21%±2.85E-5);3、SEM:The surface of polymer-ceramic is roughest, and many ceramic particles are exfoliated, remaining the resin matrix. The human enamel shows a rough surface with irregular sections. And the porcelain performed many sharp edges.4、There were more S. mutans on materials after wearing than materials before wearing.5、The number of S. mutans before wearing (1×103CFU/ml): porcelain (3.87±0.55)<polymer-ceramic(5.74±1.24)<enamel (9.52±1.04);6、 The number of S. mutans after wearing (1×103CFU/ml): porcelain (9.09±0.79)<enamel (15.51±1.35)<polymer-ceramic (12.74±1.21).Conclusions1. From porcelain, enamel to polymer-ceramic, the hardness and wear resistance of the three materials is decreasing. Porcelain tends to make the contacted teeth wearing over, because itshardness is much higher than enamel. The hardness and wear resistanceof polymer-ceramic is lower than enamel, which may lead the denture tolose more volume.2. All the three materials after wearing tend to be adhered bymicro-organism. And the adhesion atfer wearing is increasing rfomporcelain, enamel to polymer-ceramic. Porcelain is good at anti-bacteriaadhesion. But polymer-ceramic tends to be adhered by micro-organism.