Prevalence and severity of apical root resorption of maxillary anterior teeth in adult orthodontic patients.

The purpose of this study was to evaluate prevalence and severity of apical root resorption of maxillary anterior teeth in a large sample of adult orthodontic patients, to analyse any difference between subgroups of patients with and without a history of earlier orthodontic treatment, and to test the hypothesis that endodontically treated teeth are less likely to experience apical root resorption. Differences in tooth length measurements of standardized periapical radiographs made before and after treatment of 343 adults, representing groups of consecutively treated patients from four orthodontic practices, were calculated. Sample means of averaged root resorption of all six anterior teeth and of the most severely resorbed tooth per patient were 0.94 mm (SD 0.88) and 2.39 mm (SD 1.43), respectively. Forty per cent of the adults had one or more teeth with 2.5 mm resorption or greater. The subsample of 31 patients with a history of earlier orthodontic treatment had less root resorption than the remaining patients (P < 0.001). Evaluation of the 39 contralateral pairs of teeth with and without endodontic treatment in 36 of the patients revealed less resorption of the endodontically treated teeth (P < 0.05).