| Summary: | 碩士 === 國立臺灣大學 === 臨床牙醫學研究所 === 93 === Candida albicans was the most common yeast species found in denture plaque with denture stomatitis. The direct predisposing factor for denture stomatitis is the presence of the denture in the oral cavity. The tissue surface of the dentures usually shows micro-pits and microporosities, in which microorganisms are protected against shear forces. Moreover, rough surface provide a larger surface area for plaque development. Many studies have showed that C. albicans adhered in greater numbers to rougher acrylic resin. The influence of surface free-energy of the denture (represented by contact angle) on yeast adherence had also been studied by many authors, but conflicting results were reported. Few researches had been studied about these two parameters together which may have influences on the adherence of C. albicans to denture surfaces.
The aims of our study were (1) to evaluate the influences of surface roughness and surface free energy on the adhesion of Candida albicans to denture surface, and (2) to evaluate the correlation between surface roughness and surface free energy. Material and methods: 100 pieces of heat-cured acrylic resin, 20x50X1mm in size, were fabricated by the standard procedures. 10 pieces of original acrylic plates were preserved as control group; the other 90 pieces were polished by different grids of sandpapers and grouped each 10 plates by surface roughness. The surface roughness parameters (Ra, Rz) of resin plates were measured by Surftest 4 and contact angles (surface free energy) were measured by sessile drop technique. After cleaning and disinfection, all samples were immersed in the culture media which contained SC5314. One hour later, all samples were air dried and imprinted on Sabourand dextrose agar surface with constant load for 24 hours. Forming colonies on the agar were counted by automatic colony counter. All data obtained were analyzed by ANOVA and multiple regression analysis. Results: The mean surface roughness, contact angles and amounts of Candida adherence in control group were Ra 1.31±0.25μm, Rz 8.96±1.58μm, 77.8 ±7.5∘and 129.7±53.6 CFU/cm2 respectively. Comparing with control group, surface preparation significantly decreased the amounts of Candida adherence (p<0.001), but the adherence increased as the mean surface roughness increased (p<0.001). As surface roughness increases, contact angles of denture acrylic also increases (r=0.5, p<0.001). Regression analysis reveals that surface roughness more significantly influenced the Candida adhesion on denture acrylic (p=0.013) than surface free energy (p=0.55). Conclusions: Our results showed that the influence of surface roughness was greater than surface free energy on Candida adhesion to acrylic surface.
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