Oral dysbiosis: methodological evolution, the mobile resistome and the future of machine learning in dentistry

The oral microbiome acts as a significant, yet often overlooked, reservoir for antimicrobial resistance genes (ARGs). This review examines the role of the human resistome in oral health, evaluating current knowledge on the composition, function and dissemination of ARGs within the oral cavity. By comparing conventional culture-based methodologies against recent whole-genome sequencing (WGS) studies, we assess the critical role of the oral‒gut axis in resistance dissemination. The current literature indicates that horizontal gene transfer (HGT) facilitates the spread of mobile genetic elements within oral biofilms. Crucially, oral commensals, such as Fusobacterium spp., demonstrate the capacity to disseminate systemically, potentially transferring ARGs to pathogenic species. Recent WGS data further indicates a higher prevalence of ARGs in healthy individuals compared to those with dental caries, alongside an increased potential for ARG mobilisation with age. Ultimately, the dynamic oral resistome plays a vital role in both local and systemic health. Advanced methodologies, including WGS and machine learning, are essential for accurate resistome profiling and predicting antimicrobial susceptibility, which will guide prudent antibiotic prescribing in dentistry and mitigate the spread of antimicrobial resistance.