Enamel development in primary molars from children with familial dysautonomia

Familial dysautonomia (FD) is an autosomal recessive disorder, classified as a hereditary sensory and autonomic neuropathy type III, associated with growth defects affecting postnatal development. This study analysed prenatal and postnatal enamel development and postnatal calcification in upper second primary molars from FD children in comparison with healthy controls. The postnatal enamel of FD was also examined histologically for manifestation of growth insults.

The analyses were carried out on two ground sections, connecting buccal and palatinal cusp tips of mesial and distal cusps. The measurements included apical location of neonatal line, width and percentage of prenatal enamel. Chemical analyses were performed using an energy dispersive X-ray spectrometer.

The prenatal proliferative phase and prenatal apposition rate of enamel were faster on the distal cusps in FD. The postnatal enamel thickness was similar in both groups. The phosphate content of FD teeth was significantly higher and the Ca/P ratio was significantly lower. Postnatal traumatic lines were observed in all FD children and in only one healthy child.

FD upper primary second molars showed thicker prenatal enamel formation in comparison to healthy and other syndromes and better mineralisation. All FD primary molars showed large number of postnatal traumatic lines, implicating severe traumatic episodes during the first year of life.