Developmental defects in the primary teeth of children with FD

Objectives: The purpose of this study was to reconstruct the pattern of tooth development from serial microCT scans of exfoliated primary teeth of healthy controls and to compare it with that of children with Familial disautonomia (FD). Methods: the sample consisted of 10 healthy upper primary second molars (E) and 7 FD E's. Serial microCT imaging was used to differentiate between dentin and enamel and provide accurate three-dimensional reconstructions. These were used to quantify height of enamel and dentin of individual cusps at coalescence, basal crown height and total crown height. Results: Crown height tended to be greater in FD teeth .In both FD and normal teeth the palatinal cusps were taller than the buccal cusps, and had thicker enamel. The shortest cusp in the normal teeth was the MB cusp, which develops first. The tallest cusp was the DP cusp, which is the last to coalesce. In the FD teeth the DB cusp was the shortest cusp, and these differences were expressed both at the DEJ and in enamel thickness. In the normal sample the DB cusp fused first in 60%, compared to 86% in the FD sample. Since growth of any cusp is completed when it fuses with adjacent cusps the earlier fusion of the DB cusp in FD teeth may be responsible for its shorter size. Conclusions: this study represents the first attempt to differentiate between the contribution of growth reflected by the DEJ and matrix formation shown by enamel thickness in upper second deciduous molars. As cusps are initiated sequentially along a mesio-distal axis, they represent successive stages of development. The preliminary results shown here indicate that early development reflected in growth of the DB cusp may be affected in children with FD.

Acknowledgments: this research was supported by ISF grant number 032-5302.