Evaluation of the Effectiveness of Chemical Cleaning of Dentures Using a Plaque Model Consisting of Dominant Bacterial Species of Complete Denture Plaque

Abstract

　Keeping dentures clean is essential for maintaining the health of denture wearers. There are several reports on evaluating the plaque removal effect of cleaning using a plaque model in vitro. However, a plaque model that reflects the bacterial species of practical denture plaque has not been developed yet. In this study, we analyzed the flora of complete denture plaque by comprehensively sequencing the 16S rRNA gene using a next-generation sequencer. A new plaque model was built using the major constituent bacterial species and the effectiveness of the removal effect of denture cleanser was assessed. All plaques were collected from the denture base part and analyzed using the next-generation sequencer. It was clarified that Streptococcus salivarius, Veillonella dispar, Actinomyces meyeri, and Rothia mucilaginosa were dominant in complete denture plaque. A new plaque model was reconstructed on resin using the abovementioned four bacteria and a fungus, Candida albicans. When the viable cell count was measured after washing the plaque model, the cleaning agent achieved about a 4 log reduction against microorganisms in the plaque model. Additionally, confocal laser scanning microscopy observation of the plaque model with the LIVE/DEAD BacLight Bacterial Viability Kit suggested that the cleanser peeled plaque from resin and killed almost all bacterial strains in the plaque remaining on the resin. In this study, we created a new denture plaque model and constructed a basis for evaluating complete denture cleanser.