Effect of denture and soft tissue disinfection on edentulous biofilms

Oral biofilms play a central role in oral and systemic diseases. Periodontal pathogens such as Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans have been detected on dentures and oral mucosa, suggesting denture wearers remain at risk. This study aimed to evaluate whether combined denture and soft tissue disinfection reduces microbial biofilm more effectively than denture cleaning alone. Sixty-one complete-denture wearers were randomly assigned to a test group (n = 31; denture disinfection plus soft tissue chlorhexidine treatment) or a control group (n = 30; denture disinfection only). Biofilm samples from dentures, soft tissues, and saliva were collected before and after treatment and analyzed for 41 bacterial species using checkerboard DNA-DNA hybridization. Both protocols significantly reduced overall bacterial counts, including pathogens of the red complex and Streptococcus mutans. Additional soft tissue disinfection yielded greater reductions on the tongue dorsum but had limited effects at other sites. Professional denture disinfection effectively lowers microbial load in edentulous patients, and adjunctive soft tissue treatment provides added benefit. Regular implementation of this protocol may enhance oral hygiene and contribute to improved systemic health outcomes in the denture-wearing population.IMPORTANCEComplete dentures can harbor harmful bacteria not only on their dentures but also on oral soft tissues, which may contribute to oral inflammation and potentially affect systemic health. This study demonstrates that professional denture disinfection substantially reduces microbial biofilm, while the addition of soft tissue disinfection provides further improvement, particularly on the tongue. These findings support a comprehensive approach to denture hygiene that addresses both the prosthesis and the soft tissues rather than the denture alone. Incorporating combined disinfection into routine care may help improve oral hygiene, reduce the burden of disease-associated bacteria, and promote better long-term oral and systemic health in edentulous patients.