Microbial signatures of dental caries in the incarcerated elderly: a salivary microbiota study in a restricted environment

Background Dental caries is driven by microbial dysbiosis and influenced by diet and lifestyle. Incarcerated populations living under regulated regimens offer a unique model to study the oral microbiota in older adults by minimising environmental confounding variables.Objectives This study aimed to characterise the salivary microbiota of older incarcerated adults and identify bacterial taxa associated with caries status and severity.Design Twenty-eight incarcerated men (aged ≥ 50 years) were stratified into caries-active (CA) and caries-free (CF) groups (n = 14 each). The salivary microbiota was profiled using 16S rRNA gene sequencing to assess diversity and differential taxonomic abundance.Results CA subjects exhibited higher genus richness and beta-dispersion compared to CF controls. The CF group was enriched with Haemophilus parainfluenzae, Aggregatibacter sp. HMT-949 and Riemerella sp. HMT-322. Conversely, the CA group harboured elevated levels of Dialister invisus, Megasphaera micronuciformis, Prevotella intermedia, Selenomonas sputigena, Capnocytophaga ochracea and Gemella haemolysans. Furthermore, G. haemolysans, Solobacterium moorei and Streptococcus were positively correlated with caries severity, whereas Veillonella rogosae and Streptococcus koreensis and Peptostreptococcusexhibited negative correlation.Conclusion This study elucidates salivary dysbiotic signatures in older adults within a controlled environment. The identified bacterial profiles provide biomarkers for caries risk, underscoring the need for targeted oral health surveillance and preventative strategies in institutionalised populations.