Effects of different amounts of a low fluoride toothpaste on primary enamel lesion progression: a preliminary study using in vitro pH-cycling system

Aims To evaluate and compare the efficacy of pea and half-pea portions of child formula fluoride (500 ppm) toothpaste on artificially created enamel lesions in primary teeth.Methods Sound primary incisors were painted with nail varnish, leaving a 1 mm wide window and then placed in a demineralising solution for 96 h to produce artificial carious lesions 60-100 microm deep. The teeth were longitudinally sectioned (100 microm thick) and divided into 3 groups. Group A: treated with a pea-sized portion of a non-fluoride containing toothpaste (1:3, toothpaste: deionized water), while Groups B and C were treated with half-pea-sized and pea-sized portions of a 500 ppm fluoride containing toothpaste, respectively. The pH-cycling model was utilized for 7 days.Results Groups A and B lesions increased in depth by 60% while those in Group C increased by 19%. The mineral content of the surface zone decreased significantly in Groups A and B but not in Group C.Conclusion Reduction of the amount of fluoride toothpaste to less than a pea-size in order to minimize the risk of fluorosis should be undertaken with caution because it may compromise the cariostatic effects of the toothpaste.