Effect of fluoride dentifrices on the microhardness of deciduous enamel surfaces.

To evaluate the changes in the enamel surface microhardness following the application of various suspensions of Crest and Pooneh toothpastes with and without fluoride. Fifty-six enamel blocks of primary incisors were exposed to a pH-cycling regime consisting of demineralisation and remineralisation solution, then suspensions of the dentifrices Crest 1100, Crest 500, Pooneh 500, Pooneh without fluoride. Changes of the enamel surface microhardness in pre-demineralisation (initial), post-demineralisation (demineralised) and post-remineralisation (final) stages were measured for four groups and were analysed using the Student t test and one-way ANOVA. The percentages of changes in surface microhardness for Crest 1100, Crest 500, Pooneh 500 and Pooneh without fluoride were 45.4, 35.4, 28.6 and 23.7, respectively. Average changes of surface microhardness for Crest 1100 were significantly higher than Crest 500, Pooneh 500 and Pooneh without fluoride.