Inhibition of enamel lesion formation by fluoridated milk assessed by laser fluorescence--an in vitro study

The aim of this study was to investigate the effect of fluoridated milk on enamel lesion formation as assessed by laser fluorescence (LF). The material consisted of 18 extracted premolar teeth that were cut in mesial-distal direction and pairwise assigned to either test or control samples in an experimental caries model. The teeth were exposed to a low-pH 5% cellulose gel for 4 h, 5 days per week immediately followed by a 4-h period in either fluoridated (5 ppm, test) or nonfluoridated milk (control). In the meantime, the specimens were stored in pooled human-stimulated whole saliva in room temperature. All teeth were examined by visual inspection with a magnifying glass and by LF readings (DIAGNOdent) at baseline and after 2 and 4 weeks. The baseline LF readings ranged from 3 to 7 with a mean value of 5.6+/-0.9. The mean values increased with time in both groups but the increase was more marked in the control teeth, 8.7+/-2.3 vs 12.8+/-3.3 after 4 weeks, this difference being statistically significant (p<0.01). The visual examination could not distinguish between the test or control samples after 2 and 4 weeks, respectively. The findings indicated that fluoride added to milk may to some extent counteract enamel lesion formation as assessed by LF in an experimental caries model.