Effect of toothpicks with and without fluoride on de- and remineralization of enamel and dentine in situ

The aim of this investigation was to study the effect of the interproximal use of fluoride (F)-impregnated and non-impregnated birch toothpicks on the degree of de- and remineralization of enamel and dentine in situ. Ten volunteers with complete dentures in the upper jaw participated. Each subject had four specimens: (1) sound enamel, (2) demineralized enamel, (3) sound dentine and (4) demineralized dentine; placed pairwise at two approximal sites (15/16 and 25/26) of the maxillary prosthesis. The study involved three test periods (A, B and C), each lasting 4 weeks. In A, the subjects used F toothpicks (impregnated in 4% NaF) and, in B, nonimpregnated toothpicks 3 times daily. During period C, no toothpicks were used. Dentifrice or other F-containing products were not allowed during the 4-week periods. Transversal microradiography was used to determine lesion depth (ld) and mineral loss (Delta Z). The results revealed that all the sound samples lost mineral during the three experimental periods; Delta Z for both enamel and dentine was less for A and B compared with C (p < 0.01) and less for A compared with B and C for dentine (p < 0.05, p < 0.01). The demineralized samples also lost mineral, apart from dentine, during periods A and B, i.e. when F-impregnated and non-impregnated toothpicks were used; Id for enamel and Delta Z for dentine were less for A compared with C (p < 0.05). Four weeks' use of toothpicks, especially F-impregnated toothpicks, thus reduces the demineralization of enamel and dentine at approximal sites in situ.