RISK-FACTORS FOR APICAL ROOT RESORPTION OF MAXILLARY ANTERIOR TEETH IN ADULT ORTHODONTIC PATIENTS

The purpose of this study was to identify risk factors for apical root resorption in adult orthodontic patients. Standardized periapical rad iographs of maxillary anterior teeth and cephalograms made before and after treatment and treatment charts of 343 adults, representing group s of consecutively treated patients from four orthodontic practices, w ere examined. Apical root resorption was calculated by subtracting pos ttreatment tooth length measurements from the corresponding pretreatme nt measurements. Root width was measured from the mesial to the distal outline of the roots 4 mm from the apex. Root form was scored subject ively as normal, pointed, eroded, blunt, bent, and bottle shaped. Root movement was calculated from measurements of superimposed tracings of pretreatment and posttreatment cephalograms. Proximity of the central incisor roots to the palatal cortical bone was scored subjectively as present or absent. Severity of initial malocclusion and treatment var iables were collected from the charts. Multiple linear regression anal yses revealed that amount of root movement, long roots, narrow roots, abnormal root shape, and use of Class II elastics were significant ris k factors. However, the statistical model had a low explained variance , strongly suggesting a weak prediction power. No association was foun d between type of initial malocclusion, treatment time, use of rectang ular arch wires, proximity of the root to the palate or treatment with maxillary osteotomy, and root resorption. Endodontic treatment was a preventive factor.