Oral diseases, such as
periodontal disease and
dental caries, have a high risk of recurrence and are considered to be related to
dysbiosis of the oral microbiome and metabolome. It is, therefore, important to understand the state of the oral microbiome and metabolome after disease treatment to prevent recurrence. The current study sought to clarify whether oral
dysbiosis improves the following remission of symptoms by dental treatment. To this end, the salivary microbiome and metabolome of healthy participants were compared to those with
periodontal disease,
dental caries, or both (concurrent). Saliva was collected as mouth-rinsed water and the microbiome was measured using
16S rRNA gene targeted sequencing and metabolome using capillary electrophoresis-time-of-flight mass spectrometry. Comparisons with healthy participants were performed before and
after treatment, and several months after transition to self-care. Dental treatment significantly improved the oral health condition of each group; several months
after treatment, oral health did not deteriorate. However, even after remission, the salivary microbiome of the two groups (oral disease and healthy) differed significantly. Additionally, after remission, significant differences, compared with healthy participants, remained in the relative abundances of disease-related bacteria and
nitrate-reducing bacteria. After remission, significant differences were observed in the salivary metabolome in the healthy group in terms of
threonate and
pyrimidine metabolism-related component concentrations, which are assumed to reflect the high relative abundance of
periodontal disease-related bacteria in the microbiome. Oral microbiome
dysbiosis persisted even after dental treatment-induced disease remission with a sustained increased risk of disease when compared with healthy participants. IMPORTANCE We characterized the oral conditions, salivary microbiome, and metabolome after dental treatment by investigating the state
after treatment completion and transition to self-care. Dental treatment improved oral health conditions, resulting in oral disease remission; however, the imbalanced state of the salivary microbiome continued even after remission. Although the results of this study are preliminary, owing to the small number of participants in each group when compared to larger cohort studies, they indicate that the risk of disease may remain higher than that of healthy participants, thereby demonstrating the importance of removing
dental plaque containing disease-related bacteria using appropriate care even
after treatment completion. We also identified bacterial species with relative abundances that differed from those of healthy participants even after remission of symptoms, which may indicate that the maturation of certain bacterial species must be controlled to improve the oral microbiome and reduce the risk of disease recurrence.