Root exposure in the primary dentition studied in human skulls.

The aims of the present study were to examine, on the primary dentition of 75 human dried skulls, the distance from the cemento-enamel junction (CEJ) to the alveolar bone crest, and to evaluate its relation to developmental age, bone morphology and attrition. The measurements from the CEJ to the alveolar crest were longer for the maxillary teeth, the second molars showed the shortest measurements, while the cuspids showed the longest. Significant positive partial correlations were found between age and the distance from the CEJ to the alveolar crest when controlling for attrition (r = 0.64), and between age and attrition when controlling for the distance from the CEJ to the alveolar bone crest (r = 0.54). The partial correlation between migration and attrition when controlling for age proved to be not significant (r = 0.13). Significant correlations were found between age and the distances from the mental foramen to: the alveolar crest (r = 0.90), and to the lower border of the mandible (r = 0.97). These findings suggest that root exposure takes place in the primary dentition, as the result of continuous eruption at a faster rate than formation of alveolar bone, presumably to compensate for facial growth.