A possible association between early apical resorption of primary teeth and ectodermal characteristics of the permanent dentition.

The hypothesis of this study is that children with unexpected early apical resorption of the primary teeth are also predisposed to resorption in the permanent dentition. Accordingly, the aim was to perform a longitudinal study focussing on the permanent teeth in children with unexpected early apical resorption in the primary dentition. Panoramic radiographs of 12 children (7 boys and 5 girls) aged 6 years 4 months to 8 years 9 months with unexpected early apical resorption of primary teeth were identified from a dental archive of 588 patients. After written request, follow-up radiographs were obtained (2-15 year interval between early and follow-up radiographs). The radiographs were examined in order to verify the abnormal resorption pattern of the primary teeth and dental deviations in the permanent teeth, known to predispose for root resorption (i.e. invaginations, narrow crowns, abrupt root deflections, slender roots, short roots, taurodontia, agenesis, deviant pattern of eruption). Primary dentition: Two phenotypically different resorption groups were identified: group I, eight patients (resorption of the roots only), and group II, four patients (resorption of root and crown). Permanent dentition: In all 12 children, dental deviations in the permanent dentition were observed. Additionally, idiopathic external apical resorption of the permanent teeth was seen in three children, two of whom had received orthodontic treatment.

Unexpected early apical resorption of primary molars and canines.

AIM: This was to examine the resorption pattern of primary molars and canines in dentitions with advanced apical resorption even though the permanent successor had barely begun root formation and to verify the resorption process histologically. STUDY DESIGN: Panoramic or bite-wing radiographs were selected from a dentition archive of radiographs from 142 children with deviant resorption patterns. METHODS: There were 14 patients (10 boys, 4 girls) aged 6 years 2 months to 8 years 1 month selected. In 11 patients abnormal resorption occurred only in the roots (group I). In 3 patients resorption occurred in the roots as well as in the crown (group II). The degree of resorption was evaluated using Haavikko's five resorption stages, and the degree of development of the permanent successor was evaluated using Haavikko's ten formation stages [Haavikko, 1973]. For histologic study 7 teeth were decalcified, paraffin-embedded, sectioned and stained with hematoxylin and eosin and examined microscopically. RESULTS: Group I: in 5 patients severe root resorption occurred before crown formation of the permanent successor was completed. In 6 children the abnormal resorption pattern was less severe. Group II: in 3 subjects full resorption of the root complex was observed as well as partial resorption of the crown. A histological analysis confirmed the resorption process. CONCLUSION: This is the first study focussing on unexpected early resorption of primary molars and canines in 14 patients without agenesis. The study showed an abnormal resorption pattern of roots and crown of primary teeth before the permanent successor had barely begun root formation. This indicates that resorption of primary molars and canines may occur independently from eruptional processes in the succeeding permanent tooth.