Establishment and application of an intact natural model of human dental plaque biofilm

PURPOSE: Human dental plaque is implicated in a number of oral diseases. Collection of its undisturbed intact structure facilitates observing the formation and the effect of treatment. This study established a model in vivo to collect intact natural dental plaque biofilm, and observed the features and evaluated the immediate penetration and bactericidal effect of an essential oil (EO) mouthrinse on it at different periods.METHODS: Three 500 microm wide grooves were cut into hydroxyapatite (HA) discs. The discs were worn by six volunteers for 6, 24 and 48 hours, then broken into halves, one served as control, while the other received a one-minute extra-oral EO mouthrinse treatment. 5, 15 and 30 minutes later, the plaque was visualized with a vitality staining technique to observe the sustained changes of biofilm structure in situ and the effect of EO on intact biofilm. The biofilm thickness and fluorescent density of vital and total bacteria were obtained through diagram analysis, assessing the percentage of thickness and fluorescent density of vital to total bacteria. All data analysis was performed using SPSS 13.0 software package. One-way ANOVA and Student-Neuman-Keuls tests were used.RESULTS: The thickness of 6h, 24h and 48 h biofilm was (11.92 + or - 4.63) microm, (18.63 + or - 4.66)microm, (27.55 + or - 6.35) microm, respectively, which increased significantly within 48 hours (P0.05). For 6-hour samples, plaque vitality for thickness and fluorescent density decreased significantly within 5 minutes after exposure to the EO (PCONCLUSIONS: This study successfully establishes a model for collecting natural undisturbed plaque biofilm in situ, showing the changes constantly within 48 hours. EO mouthrinse has an immediate penetration and antimicrobial effect on the sustained dental plaque biofilm, especially 15 minutes later.