Agenesis of permanent teeth in 8138 Danish schoolchildren: prevalence and intra-oral distribution according to gender.

OBJECTIVE: The purpose of this study was to describe agenesis of permanent teeth in children with respect to prevalence and intra-oral distribution according to gender. METHODS AND SUBJECTS: The study was population based and included all children in one district of the municipality of Aarhus, Denmark, in 1974-1979 (1657 girls and 1668 boys) and 1992-2002 (2409 girls and 2404 boys). The children underwent systematical clinical and radiographic examination. RESULTS: The period prevalence rates were almost identical for the two time periods (1972-1979: 7.8%; 1992-2002: 7.1%). Girls were affected more frequently than boys, and affected girls had more congenitally missing teeth than affected boys. Unilateral agenesis of the second premolars was more frequent than bilateral agenesis. In children with only one congenitally missing tooth, agenesis of the upper lateral incisors was asymmetrical in girls, but not in boys, whereas the opposite was true for the lower second premolars in boys. CONCLUSION: The prevalence of agenesis of permanent teeth in Danish schoolchildren seems to be constant over time, and similar to that found in other large, population-based studies. Intra-oral distributions of congenitally missing teeth indicate gender-specific patterns.

Unilateral primary or secondary retention of permanent teeth, and dental malformations.

The purpose of the present investigation was to describe the dentition in subjects with local primary or secondary unilateral retention of two or more permanent teeth, and to elucidate the aetiology by comparing the regions of retention with the innervation pattern of the jaws. The material comprised radiographic dental orthopantomograms (OTP) from 12 patients with an age range of 6-18 years (six females and six males). The locations of retention and the dental morphology in the affected regions were analysed. Comparison with contralateral teeth was undertaken and the innervation pattern of the affected field was considered. Varying degrees of dental root malformation were found to be associated with primary and secondary retention. More pronounced root malformations were observed in subjects with several affected teeth. A connection between unilateral retained permanent teeth and temporary or permanent disruption of the nerve supply to the affected region is suggested.