Imbalances within the dental biofilm trigger dental caries, currently considered a dysbiosis and the most prevalent non-communicable disease. There is still a gap in knowledge about the dynamics of enamel colonization by bacteria from the dental biofilm in caries. The aim, therefore, was to test whether the sequence of enamel colonization by a typically commensal and a cariogenic species modifies biofilm's cariogenicity. Dual-species biofilms of Streptococcus mutans (Sm) and Streptococcus sanguinis (Ss) on saliva-coated enamel slabs were inoculated in different sequences: Sm followed by Ss (Sm-Ss), Ss followed by Sm (Ss-Sm), Sm and Ss inoculated at the same time (Sm=Ss) and the single-species controls Sm followed by Sm (Sm-Sm) and Ss followed by Ss (Ss-Ss). Biofilms were exposed to 10% sucrose, 3x/day for 5 days and the slabs/biofilms were retrieved to assess demineralization, viable cells, biomass, proteins, polysaccharides and H₂O₂ production. When compared with Sm-Sm, primary inoculation with Ss reduced demineralization (p<0.05). Both Ss-Sm and Sm=Ss sequences showed reduction in biomass, protein and polysaccharide content (p<0.05). The highest S. sanguinis viable cells and H₂O₂ production and the lowest acidogenicity were observed when Ss colonized enamel before Sm (p<0.05). Initial enamel adherence with commensal biofilms seems to induce more intense competition against more typically cariogenic species, reducing cariogenicity.

中文翻译：

---

变形链球菌和血链球菌的双物种生物膜模型在牙釉质上的竞争和龋齿。

牙齿生物膜内的失衡会触发龋齿，目前认为龋齿是一种病，是最常见的非传染性疾病。关于龋齿中来自牙齿生物膜的细菌在牙釉质定植动力学方面的知识仍然存在差距。因此，目的是测试通常由共生和致癌物质引起的牙釉质定植的顺序是否改变了生物膜的致龋性。唾液包被的牙釉质平板上的变形链球菌（Sm）和血链球菌（Ss）的双物种生物膜按不同顺序接种：Sm然后是Ss（Sm-Ss），Ss然后是Sm（Ss-Sm），Sm和同时接种Ss（Sm = Ss），单种对照先接种Sm，再接种Sm（Sm-Sm），再接种Ss，再接种Ss（Ss-Ss）。生物膜暴露于10％的蔗糖中₂ O ₂生产。与Sm-Sm相比，Ss的初次接种减少了脱矿质（p <0.05）。Ss-Sm和Sm = Ss序列均显示出生物量，蛋白质和多糖含量的减少（p <0.05）。当Ss在Sm之前定居搪瓷时，观察到最高的Sanguinis血红细胞活细胞和H ₂ O ₂产生和最低的产酸性（p <0.05）。最初的珐琅质与共生生物膜的粘附似乎诱导了与更典型的致龋物种的更激烈竞争，从而降低了致龋性。