Histological Validation of Clinical Caries Scoring in Exfoliating Primary Molars

Objective: The aim of this study was to use microscopic examination of exfoliated deciduous molars to determine the effectiveness of prior in vivo dfs scoring of deciduous molars in young children. Methods: 120 primary first molars in children between 9 and 10½ years of age that had been scored in vivo using the dfs index, were examined microscopically after exfoliation and scored for caries lesions. The method of Acevedo et al (2005 J. Clin. Res. 16, 1-8, 2005) was used for the dfs scoring in vivo and were performed by a single calibrated examiner. As teeth exfoliated, they were re-scored in vitro and then transferred to a 0.5% Chloramine T solution until time of sectioning. Each tooth was then imbedded in a cylinder of clear acrylic and sectioned mesio-distally with a diamond disc and a low speed Isomet microtome. Thickness of slices was between 150 and 200 µm. Microscopic diagnoses were done by a calibrated examiner who examined each slice under a light microscope. Statistical analyses for comparison of the results from the various examinations were by the Student T test. Results: Not surprisingly, the microscopic method detected three times more lesions than did the in vivo visual-tactile method. Lesions both clinically and microscopically were mostly on the occlusal surfaces. Next most frequent by both methods were the distal approximal surfaces. Interestingly, no lesions were seen clinically on mesial surfaces but were readily seen in this location when exfoliated and by microscopic examination. Conclusion: In vitro validation by microscopic examination clearly demonstrated that there is a large difference in the number of lesions that one can detect by microscopic than by clinical examination. It appears that detection of occlusal lesions differs because of clinical probing deficiencies whereas mesial and distal lesion detection differs because of poor accessibility clinically.