Development of dentin caries lesions in an in vitro simplified biofilm model: a pilot study

Abstract Introduction Oral laboratory biofilm models have been developed to reproduce the oral environment and the process of caries lesion formation in vitro. Objective To establish and standardize an in vitro biofilm model for the development of caries lesions in dentin. Material and method Twelve standardized bovine dentin discs were assigned into three experimental times: 4, 7, and 10 days. Samples of each experimental period were inoculated with Streptococcus mutans UA 159 in a BHI culture medium with 1% sucrose, and cultured under anaerobic conditions. The integrated hardness loss (ΔS) of dentin discs and the hardness of the substrate at different depths were considered as response variables. The ΔS data were analysed by ANOVA followed by Tukey's test, both with significance level of 5%, and the data of hardness at different depths were analysed descriptively. Result There was a higher hardness loss after 10 days of microbial growth when compared to 4 days (p = 0.034), however, there was no difference between 7 and 10 days (p = 0.853). The 4-day group showed loss of hardness of the surface layers (10-40μm) and the 10-day group showed demineralization in the deeper area around 150µm. Conclusion The proposed model was able to develop artificial caries lesions in dentin. In 7 days, the dentin sub superficial lesions were suitable to des-remineralisation studies.

【摘要 引言】口腔实验室生物膜模型已被开发，用于体外模拟口腔环境与龋损形成的过程。目的 建立并标准化一种可诱导牙本质龋损形成的体外生物膜模型。材料与方法 选取12个标准化牛牙本质圆盘，分为3组分别培养4、7、10天。各组样本均在添加1%蔗糖的脑心浸液（BHI）培养基中接种变形链球菌（Streptococcus mutans）UA 159，随后于厌氧条件下进行培养。以牙本质圆盘的综合硬度损失量（ΔS）以及不同深度处的基质硬度作为响应变量。ΔS数据采用方差分析（ANOVA）结合图基（Tukey）检验进行分析，显著性水平设定为5%；不同深度的基质硬度数据则采用描述性统计分析。结果 微生物培养10天后的硬度损失量显著高于4天组（p=0.034），但7天组与10天组之间无显著差异（p=0.853）。4天组仅出现表层（10~40μm）硬度损失，而10天组则在约150μm的深层区域出现脱矿现象。结论 本研究构建的模型可成功在牙本质中形成人工龋损；培养7天时形成的牙本质亚表层龋损，适用于脱矿-再矿化相关研究。