A study of root resorption during the initial stages of orthodontic treatment

Objective The purpose of this study was to measure the amount of external apical root resorption (EARR) by using cone beam computed tomography (CBCT) and to determine which factors were clinically relevant in predicting the extent of EARR at the initial stage of orthodontic treatment. Methods CBCT radiographs were taken before treatment (T1) and at the stage of (6.9±1.24) months of treatment (T2) in 432 teeth of 108 patients. Parameters about patient information such as gender, age at the beginning of treatment, extraction pattern, root shape and duration of follow-up were recorded. More than 1 mm of root resorption was considered to be clinically significant. Results Average root resorption of upper incisors was (0.45±0.49) mm, whereas the maximum amount of resorption was 4.58 mm. Clinically significant resorption was found in 13.8% of the incisors and 27.8% of the patients, only 2% of the incisors and 6.5% of the patients had the severe root resorption. Multivariate linear regression showed that the parameters recorded were not identified as risk factors to root resorption. Conclusions Root resorption of upper incisors is common at the initial stage of orthodontic treatment, but the resorption is usually slight. Individual susceptibility might be a major cause related with root resorption at the initial stage of treatment Key words: Cone beam computed tomography (CBCT);  Orthodontic tooth movement;  External apical root resorption