Role of Candida albicans on enamel demineralization and on acidogenic potential of Streptococcus mutans in vitro biofilms

Abstract There is growing evidence that C. albicans is associated with dental caries, but its role on caries development needs to be better clarified. Objective: To evaluate at the hard tissue level the effect of C. albicans on the cariogenic potential of S. mutans biofilms focusing on the mineral profile of induced carious lesions. This study also aimed to evaluate the effect of C. albicans on the acidogenic potential of S. mutans biofilms. Methodology: Dual-species (CA+SM) and single-species biofilms (CA or SM) were grown on the surface of enamel slabs in the presence of glucose/sucrose supplemented culture medium for 24, 48 and 72 hours. Demineralization was evaluated through percentage of surface microhardness change (%SMC) and transversal microradiography analysis (ILM and LD) and pH of the spent medium was recorded daily. Data were analyzed by two-way ANOVA followed by Bonferroni correction. Results: %SMC was statistically different among the biofilms at each time point being the highest for SM biofilms and the lowest for CA biofilms which also differed from CA+SM biofilms [SM (24 h: 47.0±7.3; 48 h: 66.3±8.3; 72 h: 75.4±3.9); CA (24 h: 7.3±3.3; 48 h: 7.1±6.4; 72 h: 6.6±3.6); CA+SM (24 h: 35.9±7.39.1; 48 h: 47.2±9.5; 72 h: 47.6±9.5)]. pH of spent medium was statistically lower for SM biofilms compared to the other biofilms at each time point and remained constant over time while pH values increased from 24 to 72 h for both CA and CA+SM biofilms [SM (24 h: 4.4±0.1; 48 h: 4.4±0.1; 72 h: 4.5±0.1); CA (24 h: 6.9±0.3; 48 h: 7.2±0.2; 72 h: 7.5±0.2); CA+MS (24 h: 4.7±0.2; 48 h: 5.1±0.1; 72 h: 6.1±0.6)]. IML and LD for SM biofilms increased over time while no difference was observed from 24 to 72 h for the other biofilms. Conclusions: The present data suggest that C. albicans has low enamel demineralization potential and the presence of C. albicans can reduce both the cariogenic and acidogenic potentials of S. mutans biofilms.

摘要
越来越多的证据表明，白色念珠菌（Candida albicans, C. albicans）与龋病相关，但其在龋病发生发展中的作用仍有待进一步阐明。
研究目的：从硬组织层面评估白色念珠菌对变形链球菌（Streptococcus mutans, S. mutans）生物膜致龋潜力的影响，重点关注诱导龋损的矿物质谱；同时探讨白色念珠菌对变形链球菌生物膜产酸潜力的影响。
研究方法：将双菌种生物膜（C. albicans+S. mutans，简写为CA+SM）与单菌种生物膜（仅C. albicans或仅S. mutans，简写为CA或SM）接种于牙釉质薄片表面，使用添加葡萄糖/蔗糖的培养基培养24、48及72小时。通过表面显微硬度变化率（%SMC）与横向显微放射成像分析（ILM与LD）评估脱矿程度，并每日记录培养基上清液的pH值。数据采用双因素方差分析（two-way ANOVA）后进行邦费罗尼（Bonferroni）校正。
研究结果：各时间点下不同生物膜组的表面显微硬度变化率均存在统计学差异，其中变形链球菌单菌种组的变化率最高，白色念珠菌单菌种组最低，双菌种组介于两者之间，具体数据如下：SM组（24h：47.0±7.3；48h：66.3±8.3；72h：75.4±3.9）；CA组（24h：7.3±3.3；48h：7.1±6.4；72h：6.6±3.6）；CA+SM组（24h：35.9±7.3；48h：47.2±9.5；72h：47.6±9.5）。培养基上清液pH值方面，各时间点下变形链球菌单菌种组的pH值均显著低于其他组别，且随时间变化保持稳定；而白色念珠菌单菌种组与双菌种组的pH值则随培养时间从24h至72h逐渐升高，具体数据如下：SM组（24h：4.4±0.1；48h：4.4±0.1；72h：4.5±0.1）；CA组（24h：6.9±0.3；48h：7.2±0.2；72h：7.5±0.2）；CA+SM组（24h：4.7±0.2；48h：5.1±0.1；72h：6.1±0.6）。变形链球菌单菌种组的ILM与LD值随培养时间逐渐升高，其余两组在24h至72h间未观察到显著差异。
研究结论：本研究数据表明，白色念珠菌自身的牙釉质脱矿潜力较低，且其存在可降低变形链球菌生物膜的致龋与产酸潜力。