effect of chewing gums with xylitol, sorbitol and xylitol-sorbitol on the remineralization and hardness of initial enamel lesions in situ

background: the purpose of this study was to determine the effect of three chewing gums and paraffi n on the remineralization and the hardness of demineralized enamel. materials and methods: a total of 12 subjects wore intraoral palatal appliances with two demineralized bovine enamel slabs. the study consisted of four experimental periods each lasting 21-days, during which subjects were assigned to one of three gum-chewing regimens: gum containing sorbitol, xylitol and a mixture of sorbitol and xylitol and with paraffi n as control. the appliances were worn during gum-chewing for 20 min and then retained for 20 min 4 times/ day. the slabs were subjected to energy dispersive x-ray spectroscopy analysis and surface microhardness measurements before in setting into the appliance and after the experimental period. the data were subjected to analysis of variance for repeated measures. a p < 0.05 was considered statistically signifi cant. results: mineral analysis revealed no signifi cant difference between the baseline and after chewing periods for all groups (p > 0.05). no signifi cant difference was found among the groups either for the baseline measurements or after chewing periods (p > 0.05). all groups showed higher microhardness values after the chewing periods than the baseline except for the vivident xylit group (p < 0.05). conclusion: the chewing of gum had no effect on the ca/p ratio of demineralized enamel surfaces. the hardening of the demineralized enamel surfaces may vary according to the type of chewing gum. key words: chewing gum, enamel, energy dispersive x-ray spectroscopy, microhardness