Candida-bacteria interactions in peri-implantitis: A narrative review of evidence, mechanisms, and clinical...

To critically synthesize clinical, molecular, and mechanistic evidence on the contribution of the oral mycobiome, particularly Candida albicans, to peri-implantitis, and to evaluate how fungal-bacterial interactions influence biofilm pathogenicity, host responses, and potential therapeutic implications.

Narrative review of peer-reviewed studies including clinical and epidemiological investigations, molecular analyses (quantitative polymerase chain reaction [qPCR] and next-generation sequencing [NGS] targeting the internal transcribed spacer [ITS] region for fungal profiling and the 16S ribosomal RNA [16S rRNA] gene for bacterial profiling), in vitro and in vivo interkingdom biofilm models, and immunological mechanistic studies. Evidence was evaluated qualitatively, with emphasis on detection methods, study design, and translational relevance.

Molecular studies detect Candida spp. in a notable fraction of peri-implantitis sites, with higher detection by qPCR/NGS than by culture. Co-occurrence of C. albicans with periodontopathogens (e.g., Porphyromonas gingivalis, Fusobacterium nucleatum) is frequently reported. Mechanistic studies show that C. albicans forms hyphal scaffolds, consumes oxygen to create microanaerobic niches, mediates bacterial adhesion via Als adhesins, and participates in metabolic exchange and cooperative proteolysis. These processes enhance biofilm resilience, promote inflammatory signalling pathways (nuclear factor kappa B [NF-κB] and mitogen-activated protein kinase [MAPK]), activate the NLRP3 inflammasome, and increase antimicrobial tolerance. No randomized controlled trials of antifungal or interkingdom-directed therapies are currently available.

Evidence supports an interkingdom, polymicrobial model of peri-implantitis in which fungi contribute to biofilm stability and inflammation. However, heterogeneity in definitions, sampling, and detection methods limits causal inference. Longitudinal and interventional studies are required before mycobiome-directed therapies can be recommended.