Prospective study of the effect of post-brushing rinsing behaviour on dental caries.

Previous studies have indicated that rinsing the mouth with a beaker of water after toothbrushing may compromise the caries reducing effect of fluoride toothpaste. A 3-year clinical trial of daily supervised brushing with fluoride toothpaste at school was used to test the effect of post-brushing rinsing with water on caries increment. A total of 407 children, mean age 11.8 years, attending three schools in Kaunas, Lithuania were enrolled following informed consent of the children and their parents. Caries was recorded at baseline and annually for 3 years. During the study, children in two schools (A and B) performed daily supervised brushing with a 1,500-ppm fluoride toothpaste. Children in school A rinsed their mouths thoroughly with a beaker of water after toothbrushing whereas children in school B were only permitted to spit out once after brushing. Furthermore, the children in these schools were supplied with toothpaste and toothbrushes for use at home and in school. A third school (C), without daily brushing and without supply of toothpaste, served as control. Compliance with the protocol was consistently better in school B. After 3 years 276 children were available for examination. Three-year DMFS increments, including non-cavitated lesions (mean, 95% CI), were: school A, 6.8 (5.3; 8.3); school B, 6.2 (4.6; 7.8), and school C, 12.4 (10.6; 14.1). Mean increments for schools A and B did not differ significantly but were both significantly lower than those of school C (p< 0.001). It is concluded that post-brushing rinsing with water, under the conditions of this study, does not significantly affect the caries reducing effect of a fluoride toothpaste.