Physical-Mechanical Properties of Bulk Fill Composites Submitted to Biodegradation by Streptococcus mutans

Abstract The aim of this study was to evaluate the Streptococcus mutans biofilm influence on the roughness (Ra), gloss (GU), surface hardness (KHN) and flexural strength (FS) of high viscosity bulk fill composites. Filtek Bulk Fill (FBF), Tetric N Ceram Bulk Fill (TNC), X-tra fil Bulk Fill (XF) and Filtek Z350 (FZ) were used. Ten discs of each composite were prepared for Ra, KHN and GU and 20 bars for the FS. After 24 h, specimens were polished and initial analyzes performed. Samples were sterilized and subjected to biodegradation for 7 days and final analyzes performed. Representative samples of each group were evaluated in Scanning Electron Microscope. Data were submitted to ANOVA two factors and Tukey test. XF presented the highest values (p<0.05) of Ra before and after biodegradation (0.1251; 0.3100), and FZ (0.1443) the lowest after biodegradation (p<0.05). The highest GU values (p<0.05) were observed for FZ (71.7; 62) and FBF (69.0; 64.6), and the lowest (p<0.05) for TNC (61.4; 53.3) and XF (58.5; 53.5), both before and after biodegradation. For KHN the highest values were obtained by XF (151.7; 106), and the (p< 0.05) lowest values for TNC (62.2; 51.8), both before and after biodegradation. The highest values (p<0.05) of FS were observed for FZ (127.6) and the lowest (p<0.05) for TNC (86.9); after biodegradation, XF (117.7) presented the highest (p<0.05) values compared to TNC and FZ.” In conclusion, biodegradation increased Ra and decreased GU and KHN for all. Concerning FS, degradation provided a significant decreased value only for FZ.

摘要 本研究旨在评估变形链球菌(Streptococcus mutans)生物膜对高粘度大块充填复合树脂的粗糙度(Ra)、光泽度(GU)、表面硬度(KHN)及弯曲强度(FS)的影响。本研究选用Filtek Bulk Fill(FBF)、Tetric N Ceram Bulk Fill(TNC)、X-tra fil Bulk Fill(XF)及Filtek Z350(FZ)四种复合树脂作为受试材料。每组制备10个圆盘状试样，用于粗糙度、表面硬度及光泽度检测；另制备20个条形试样用于弯曲强度检测。试样静置24小时后完成抛光操作，并进行初始性能检测。随后对所有试样进行灭菌处理，经7天生物降解处理后，开展最终性能检测。每组选取代表性试样，采用扫描电子显微镜(Scanning Electron Microscope)进行形貌观察。实验数据采用双因素方差分析(ANOVA two factors)及Tukey检验(Tukey test)进行统计学分析。结果显示，生物降解前后，XF的粗糙度值均为最高(p<0.05)，分别为0.1251和0.3100；生物降解后，FZ的粗糙度值最低(p<0.05)，为0.1443。光泽度方面，生物降解前后FZ(71.7; 62)与FBF(69.0; 64.6)的光泽度值均为最高(p<0.05)，而TNC(61.4; 53.3)与XF(58.5; 53.5)的光泽度值均为最低(p<0.05)。表面硬度方面，XF的表面硬度值最高，生物降解前后分别为151.7和106；而TNC的表面硬度值最低(p<0.05)，分别为62.2和51.8。弯曲强度方面，生物降解前FZ的弯曲强度值最高(p<0.05)，为127.6，TNC最低(p<0.05)，为86.9；生物降解后，XF的弯曲强度值最高(p<0.05)，显著高于TNC与FZ。综上，生物降解会使所有受试复合树脂的粗糙度升高，同时降低其光泽度与表面硬度。就弯曲强度而言，生物降解仅会使FZ的弯曲强度出现显著下降。