Early onset of enamel formation in Baka pygmy’s deciduous canines

Abstract

Objective

Our aim was to evaluate by enamel microstructure analysis two hypotheses that would explain the early dental eruption in the Bakaparticularity, a shorter crown formation time and/or earlier onset of crown formation.

Design

Deciduous canines corresponds to the best teeth to perform the analysis of enamel microstructure. Longitudinal ground sections of 21 deciduous canines from 12 individuals were studied with transmitted light microscopy. Cross-striations, striaes of Retzius (SR) and the neonatal line (NNL) enable to establish the prenatal crown formation time (preCFT), the postnatal crown formation time (postCFT), the crown formation time (CFT) as well as the daily secretion rate (DSR) and the enamel extension rate (EER) and their variation along crown formation.

Results

The DSR and the EER in the Baka are similar than in other populations with an average DSR of 3.26 µm and EER of 18.18 µm. The preCFT was 154 days, the postCFT 265 days and CFT 419 days. Comparison with other population does not show difference in CFT. However, the preCFT and the postCFT differ, the first is higher and the second lower in the Baka than in other populations. Furthermore, the number of prenatal areas of enamel was greater in the Baka.

Conclusion

Our analysis suggests that the Baka does not distinguish by a different CFT but the onset of crown formation is earlier than in other groups. Therefore, the early dental eruption in the Baka results from an earlier onset of crown formation.