Submucosal microbiota profile in peri-implant health, peri-implant mucositis, and different severity levels of peri-implantitis

The unique and complex peri-implant microbiota harbors many species, mostly bacteria, and dysbiotic shift in microbiota induces peri-implant diseases. The aim of the study was to investigate the compositions and differences in submucosal microbial profiles in subject with different peri-implant heath statues, from peri-implant healthy (PH) to advanced peri-implantitis (PI). Submucosal plaque samples were obtained from 78 individuals with PH, peri-implant mucositis (PM), early, moderate, and advanced PI (PH:16, PM:16, PI-early: 14, PI-moderate: 16, and PI-advanced:16) and analyzed using sequencing of 16S rRNA gene. Differences of submucosal microbiome profiles between groups were evaluated with taxonomic abundances and microbial diversity using the alpha-diversity metrics (observed features, Shannon index, and Chao1 index), beta-diversity metrics (Bray–Curtis dissimilarity, unweighted, and weighted UniFrac distance), and linear discriminant analysis effect size analysis. According to alpha-diversity and beta-diversity analysis, the submucosal microbiota diversity showed no difference in the PI, PM, and PH sites. Prevotella, Fusobacterium, Bacteroides, Treponema, Porphyromonas, Fretibacterium, and Veillonella genera showed high abundance in the PI groups. At the genus-level, compositional differences between two distinct clinical groups were found. Pseudoramibacter was significantly enriched in PM and PI groups compared to PH. Fretibacterium was the most discriminative taxa between PI-early and PH. Despite similar overall microbial diversity, distinct compositional shifts in the submucosal microbiota were observed across peri-implant health and disease. Specific genera, particularly Fretibacterium and Pseudoramibacter, were associated with disease conditions and may serve as potential candidates for future biomarker research. These findings suggest that microbial composition, in addition to diversity, could be relevant to understanding peri-implant disease processes and may inform the development of diagnostic and preventive strategies.