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 (DeltaZ). The results revealed that all the sound samples lost mineral during the three experimental periods; DeltaZ 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; ld for enamel and DeltaZ 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.