The influence of toothbrushing frequency and post-brushing rinsing on caries experience in a caries clinical trial

Objective: To examine the effect of reported toothbrushing frequency and method of rinsing after brushing on caries experience and increment. Methods: Data are presented from 2621 adolescents (mean age 12.5 years at outset) participating in a 3-year double-blind caries clinical trial. At baseline, examiners questioned each participant about their toothbrushing habits, and at subsequent examinations, this information was obtained using a self-administered computer-based questionnaire. participants used a fluoride-containing dentifrice throughout and clinical examinations were conducted using a mirror, CPITN probe and fibre-optic transillumination. Results: The reported brushing frequency increased throughout the trial. Caries experience at baseline was inversely related to toothbrushing frequency with mean DMFS=9.66, 8.12 and 7.63 respectively for <1/day 1/day and >1/day brushers (P<0.001). Mean 3-year DMFS increments of 8.90, 6.63 and 5.48 (P<0.01) were observed in those reporting to brush <1/day, 1/day or >1/day on not less than two of the three clinical examinations during the trial. Caries increment was also significantly related to the claimed method used to rinse post-brushing. Overall frequency of brushing and rinsing method accounted for over 50% of the explained variance in the ANOVA model used to analyse the DMFS increments. Conclusions: Stated toothbrushing frequency and rinsing method after brushing were found to be strongly correlated with caries experience and caries increment. These factors should be reflected in the design of oral health education material and taken into account in the design and analysis of caries clinical trials.