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 and analyzed using sequencing of 16S ribosomal RNA gene. Differences of submucosal microbiota profiles between groups were evaluated with the alpha-diversity, beta-diversity, 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 biomarkers for disease progression. These findings highlight the importance of microbial composition, rather than diversity alone, in the pathogenesis of peri-implant diseases and may contribute to developing diagnostic and preventive strategies.