MICROBIOME MODULATION THERAPY IN ORAL DISEASES: A NARRATIVE REVIEW

Abstract

Background: The major oral diseases are no longer understood as infections by single pathogens but as ecological disorders, in which a resident microbial community shifts from a symbiotic to a dysbiotic state under environmental pressure. This reframing implies that therapy might restore the community rather than eliminate it, and has produced a large literature on probiotics, prebiotics, postbiotics, targeted antimicrobials and microbiota transplantation. Objective: To evaluate microbiome modulation therapy across the spectrum of oral disease according to the level of evidence each strategy has attained, and to identify why a field with abundant randomised trials has produced so little that has changed practice. Methods: A narrative review was conducted. PubMed, Embase, the Cochrane Library and ClinicalTrials.gov were searched on microbiota-modulating interventions in dental caries, periodontitis, peri-implant disease, oral candidiasis, halitosis and cancer therapy-induced oral mucositis. Randomised trials, meta-analyses, observational studies, preclinical work and trial registrations were eligible. Findings: Evidence is extensive but varies in quality and strength. Probiotics reduce caries in children, but not adults; improve periodontitis short-term when added to mechanical debridement; reduce bleeding, but not probing depth, in peri-implant mucositis; and lessen severe mucositis during cancer therapy. An 8% arginine dentifrice reduced caries increment versus fluoride in a 6,000-child phase 3 trial, making substrate modification the strongest-supported ecological strategy. Postbiotics, synbiotics, and nitrate approaches remain largely limited to surrogate microbiological outcomes, while C16G2 completed phase 2 without published efficacy data. Replacement therapy, phage therapy, and oral microbiota transplantation remain preclinical or early-stage. Conclusions: The obstacle in this field is not a shortage of trials but a shortage of trials that measure disease. Reliance on microbiological surrogates, the transience of exogenous colonisation, and the regulation of most products as foods rather than medicines have together produced a literature that is large, positive and largely unable to support clinical recommendation.