Initial caries diagnosis in rat molars, using laser fluorescence

Scoring of enamel caries in rat molars in ordinary light and in laser fluorescence was compared. Fifty rats were infected with Streptococcus mutans; 5 served as control rats, and the other 45 were fed a cariogenic diet for 15-20 days. With Keyes's system, the total enamel caries score for 35 of the test rats was 29.1 lesions per rat (l/r) in ordinary light and 39.6 l/r in laser fluorescence. The corresponding scores for fissure caries were 15.9 l/r and 21.6 l/r, respectively. Fissure caries scores of thin, longitudinal, central sections from the molars of the 10 remaining test rats were 18.0 l/r in ordinary light, 21.4 l/r in laser fluorescence, and 17.1 l/r in microradiographic analysis. In conclusion, the use of laser fluorescence improves scoring of early enamel carious lesions in rat molars, offering potential reductions in test time and/or sucrose load in animal caries research.