Longitudinal effects of antiretroviral therapy on the oral microbiota in people living with HIV: A systematic review

People living with HIV frequently experience oral microbial dysbiosis, contributing to oral disease burden and reduced quality of life. Although antiretroviral therapy (ART) effectively suppresses viral replication and promotes immune recovery, its longitudinal effects on the oral microbiota remain incompletely understood. This systematic review aimed to evaluate longitudinal changes in oral microbiota composition and diversity in people living with HIV before and after ART initiation. A systematic review was conducted in accordance with PRISMA guidelines and registered in PROSPERO (CRD420251164326). Electronic searches were performed in PubMed, ScienceDirect, Wiley Online Library, DOAJ, and Google Scholar for studies published between 2015 and 2024. Eligible studies included longitudinal human studies reporting pre- and post-ART oral microbiota data using 16S rRNA gene sequencing or metagenomic approaches. Methodological quality was assessed using Joanna Briggs Institute critical appraisal tools. Due to substantial heterogeneity, findings were synthesized narratively. Six longitudinal studies met the inclusion criteria. ART was associated with partial and non-uniform modulation of the oral microbiota. Changes in beta diversity and selective taxonomic shifts were commonly reported, whereas changes in alpha diversity were inconsistent. Taxonomic alterations were more evident at the genus level, while several dominant oral genera remained stable before and after ART. Evidence linking oral microbiota changes with immune recovery was limited. Longitudinal evidence indicates that ART induces selective and heterogeneous changes in the oral microbiota without consistent normalization toward a non-HIV microbial profile, underscoring the importance of integrating oral health into long-term HIV care.