We used a polymicrobial (PM) biofilm model to examine associations of bacterial adhesiveness with surface characteristics of various dental materials. Four types of dental materials (apatite pellet, zirconia, ceramic, and composite resin) with rough and mirror surfaces were used. Surface roughness, surface free energy, zeta potential, and colony-forming units (CFUs) of the biofilm formations were measured. Biofilms were cultured for 24 h under anaerobic conditions, plated onto blood agar medium, and anaerobically cultured for 4 days. After culturing, CFU per mm 2 was calculated, and samples were observed under a scanning electron microscope. Means and standard deviations of the experimental data were estimated, and one-way ANOVA and Tukey multiple comparison assays were performed. Pearson correlation coefficients were obtained for the CFU and surface characteristics. Surface roughness and surface free energy appeared to affect generation of PM biofilms on oral materials, and zeta potential was involved in generation of PM biofilms on mirrorground oral materials.

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Background: Silane coupling agents are used as a bonding agent between ceramics and resins in dentistry. The effectiveness of these agents is often enhanced by the addition of acid or by heat treatment. Objective: This study aimed to evaluate, the clinical characteristics, TBS (tensile bond strength) and water resistance of eight commercial ceramic primers (seven silane coupling agents and one alumina zirconia primer). Method: Glass plates were used as the adherent. The TBS of the resin composite and the wettability of the resin monomer to glass surfaces treated with ceramic primers was investigated, with 3-MPS (methacryloxypropyltrimethoxysilane) used as a control. The values obtained from the experiments were analyzed using one-way ANOVA followed by Tukey's multiple comparison tests (p < 0.05). Results: No significant differences in TBS were observed between the commercial products and MPS, except for the alumina zirconia primer. However, four products (three of the seven agents and the alumina zirconia primer) exhibited significantly lower TBS values after application of thermal stress when compared with those stored in water (p < 0.05). All but one of the eight primers displayed significantly higher contact angles between the treated glass and the resin monomer when compared with MPS (p < 0.05). These results suggest that some commercial ceramic primers may contribute to increased strength and durability.