Influence Of Different Surface Treatments On Surface Characteristics And Bacterial Adhesion Of Dental Ceramic Material

Ceramic restorative materials has been widely used in clinical practice, due to the excellent aesthetic properties, biocompatibility, high corrosion resistance and wear resistance. Especially in recent years, with the extensively application of implants,all-ceramic materials are used increasingly as individualized abutments. Lithium disilicate glass ceramic and zirconia are two kinds of ceramics which have been frequently used in dental restorations. A novel lithium disilicate glass ceramic was also developed in our previous study. Moreover, in order to avoid the occurrence of porcelain fracture,fabrication of ceramic prosthesis with full anatomical structure of glass ceramic or zirconia has become popular. Before cemented into the patient’s mouth, adjustment of the ceramic restoration is necessary to produce suitable occlusal contact or appearance.However, these adjustments destroy the smooth surface of ceramic prosthesis. In clinicalpractice, polishing or glazing treatment is used, which would produce different surface roughness and surface free energy of materials. Surface roughness and surface free energy are two important factors that would affect bacterial adhesion in oral condition. Therefore,the objectives of the present study were to investigate the influence of different surface treatments on surface roughness, surface free energy and bacterial adhesion of dental ceramics.The research was divided into three parts:Part one: To investigate the influence of different surface treatments on roughness and surface free energy of dental ceramics. Specimens of four dental ceramics were prepared and randomly subjected to three treatments: grinding, polishing or glazing. The three-dimensional profilometer was used to measure the surface roughness of dental ceramics after different surface treatments and the 3d images of surface were also recorded. The contact angle was measured and the surface free energy of each specimen was calculated. For all ceramics, the surface roughness value of the grinding group was significantly higher than that of the polishing group or glazing group. For zirconia ceramics, polishing and glazing groups achieved similar roughness value. As for glass ceramics, compared with glazing group, polishing groups showed significantly lower roughness value. Moreover, specimens after glazing treatment had the highest surface free energy.Part two: To investigate the influence of different ceramic surface of dental ceramic material on the adhesion of Streptococcus mutans. The measurement of optical density values and CFU count were used. The microstructure was observes using the CLSM and SEM. The highest amount of S. mutans was found for grinded specimens for all ceramics tested. Polishing and glazing treatment can significantly reduce the adhesion of Streptococcus mutans on ceramic materials. Polishing group showed the lowest amount of S. mutans.Part three: To investigate the influence of different ceramic surface on the adherence of plaque adhesion of dental ceramic material. Optical density values were measured and SEM was used for microstructure observation. The amount of plaque adhesion on theground ceramic was significantly higher than that of polished and glazed materials.Compared with the glazing ceramic materials, polishing group showed lower amount of bacterial adhesion.