ABSTRACT

Aim: This in vivo experimental study investigated bacterial microbiome and metabolome longitudinal changes associated with enamel caries lesion progression and arrest.

Methods: We induced natural caries activity in three caries-free volunteers prior to four premolar extractions for orthodontic reasons. The experimental model included placement of a modified orthodontic band on smooth surfaces and a mesh on occlusal surfaces. We applied the caries-inducing protocol for 4- and 6-weeks, and subsequently promoted caries lesion arrest via a 2-week toothbrushing period. Lesions were verified clinically and quantitated via micro-CT enamel density measurements. The biofilm microbial composition was determined via 16S rRNA gene Illumina sequencing and NMR spectrometry was used for metabolomics.

Results: Biofilm maturation and caries lesion progression were characterized by an increase in Gram-negative anaerobes, including Veillonella and Prevotella. Streptococcus was associated caries lesion progression, while a more equal distribution of Streptococcus, Bifidobacterium, Atopobium, Prevotella, Veillonella, and Saccharibacteria (TM7) characterized arrest. Lactate, acetate, pyruvate, alanine, valine, and sugars were more abundant in mature biofilms compared to newly formed biofilms.

Conclusions: These longitudinal bacterial microbiome and metabolome results provide novel mechanistic insights into the role of the biofilm in caries progression and arrest and offer promising candidate biomarkers for validation in future studies.

摘要

目的：这项体内实验研究调查了与牙釉质龋齿病变进展和停滞相关的细菌微生物组和代谢组纵向变化。

方法：在出于正畸原因拔除四颗前磨牙之前，我们在三名无龋齿志愿者中诱导自然龋齿活动。实验模型包括在光滑表面上放置改良的正畸带，在咬合面上放置网格。我们应用了 4 周和 6 周的龋齿诱导方案，随后通过 2 周的刷牙期促进龋齿病变的抑制。通过显微 CT 牙釉质密度测量对病变进行临床验证和定量。通过 16S rRNA 基因 Illumina 测序确定生物膜微生物组成，并使用 NMR 光谱法进行代谢组学。

结果：生物膜成熟和龋齿病变进展的特点是革兰氏阴性厌氧菌（包括韦荣球菌和普雷沃菌）的增加。链球菌与龋齿病变进展相关，而链球菌、双歧杆菌、Atopobium、普雷沃氏菌、韦荣氏菌和糖杆菌 (TM7)的更均匀分布则表现为停滞。与新形成的生物膜相比，成熟生物膜中的乳酸、乙酸盐、丙酮酸、丙氨酸、缬氨酸和糖更丰富。

结论：这些纵向细菌微生物组和代谢组结果为生物膜在龋齿进展和阻止中的作用提供了新的机制见解，并为未来研究中的验证提供了有希望的候选生物标志物。