 Materials and Methods. Forty volunteers were selected among students of dental medicine and assigned into two experimental groups. Each group used regular non-fluoride toothpaste for initial two months, followed by the use of fluoride toothpaste of the same brand for the next two months. The buccal epithelial cells were sampled at baseline and 30, 60, 90 and 120 days after the beginning of the research. Chromosomal damages were analyzed by micronucleus assay. 