義齒樹脂表面性質對白色念珠菌黏附的影響

Abstract

口腔內義齒的存在是形成義齒性口炎最直接的誘發因素。義齒的組織面在電子顯微鏡的檢視下常可見到許多細微的裂隙或微細孔洞，這些地方提供了微生物一個很好的保護，不論使用機械性或化學性的清除方法都有所困難。在粗糙的表面上，念珠菌較能受到保護而不被輕易移除。早期研究牙菌班的結果顯示，口內的一些粗糙表面，不論是軟組織或硬組織，會影響微生物初始的黏附及其之後的發展。另外也有許多學者提出關於樹脂表面疏水性對於白色念珠菌黏附的影響，結果至今仍未有定論。而關於表面粗糙度與疏水性這兩項影響白色念珠菌對樹脂黏附能力的因素，很少有文獻提及其相對的重要性。 本實驗的目的在於評估義齒樹脂表面粗糙度及親水性之間相關性及其對白色念珠菌黏附的影響。實驗材料與方法：以臨床上製作活動義齒之標準程序製備樹脂試片100片，大小為50 x 20 x1mm。隨機選取10片樹脂不做任何表面處理，當作控制組；其餘90片則以粗細不同的砂紙做拋光處理，依其表面粗糙程度的不同將其分成九組，每組各10片。樹脂表面粗糙度參數 (Ra, Rz) 經由表面粗糙度測定器Surftest 4量得；而樹脂表面親水性則藉由水滴法(sessile drop technique)求得其接觸角(contact angles)。所有實驗試片皆以超音波震盪器洗淨消毒後，在無菌的操作技術下將其浸泡在含有濃度約104 cells/ml 白色念珠菌(SC5314)的培養液中。一小時後，將所有試片取出在室溫下陰乾，並以固定的力量壓印於培養基(Sabourand dextrose agar)上，培養24小時。在培養基上形成的菌落以automatic colony counter計數。所有的資料結果，以ANOVA及多變數回歸分析了解各因子間的相關性。結果：在控制組中測得的樹脂表面粗糙度、接觸角，白色念珠菌黏附數，其平均值依次為Ra 1.31±0.25μm, Rz 8.96±1.58μm, 77.8 ±7.5∘和 129.7±53.6 CFU/cm2。與控制組比較，樹脂表面經由磨光處理後，白色念珠菌黏附數有明顯的降低(p<0..001)；然在實驗組中白色念珠菌黏附數仍隨著樹脂表面粗糙度的增加而明顯的增加(p<0.001)。隨著樹脂表面粗糙度的增加，其疏水性也隨之增加，即接觸角的變化與表面粗糙度的增加有顯著的相關性(r=0.5, p<0.001)。回歸分析的結果顯示，對於白色念珠菌黏附的影響力，樹脂表面粗糙度(p=0.013)遠比親水性(p=0.55)要來的大。結論：我們的研究結果顯示樹脂表面粗糙度對於白色念珠菌黏附的影響力比親水性大，且表面越粗糙，念珠菌的黏附數越高。

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.