Structure and Function of the Dental Plaque Microbiome in Eubiosis: A Systematic Review of Ethnic Influences

The human oral microbiome has traditionally been described as universal; however, the influence of genetic ancestry on the structure of supragingival plaque in a healthy state (eubiosis) remains unclear compared to other environmental factors. To this end, a systematic review was conducted following the PRISMA 2020 guidelines. The search was carried out in PubMed, Scopus, ScienceDirect, and Scielo, including literature from the last 20 years. Cross-sectional observational studies that used genomic sequencing (16S rRNA/rDNA) or metagenomics were included. The certainty of primary evidence will be assessed using the GRADE approach. Six studies were included after meeting the eligibility criteria. A universal core microbiome was identified, structurally dominated by Corynebacterium spp. and Streptococcus spp. However, ethnic-specific taxonomic signatures were found, such as the enrichment of Fusobacterium spp. in African Americans (AA) and Corynebacterium spp. in Caucasians (CA), as well as the exclusive presence of the taxon Sneathia spp. in Burmese (BM). These results indicate that although there is a basal microbial architecture necessary for dental homeostasis, ethnicity acts as a biological filter that defines distinctive bacterial profiles and differential susceptibilities. Our findings, also modulated by the host environment, may suggest a shift from standardized care to more personalized care oriented toward the patient's ancestry.