Is Short Root Anomaly (SRA) a risk factor for increased external apical root resorption in orthodontic patients? A retrospective case control study using cone beam computerized tomography

To evaluate the amount of external apical root resorption (EARR) secondary to orthodontic treatment in patients with Short Root Anomaly (SRA) compared to patients with average root lengths using Cone Beam Computed Tomography (CBCT).Cone beam computed tomography scans of 23 SRA and 26 control patients were selected from 232 pretreatment scans from a single private practice.Cone beam computed tomography scans before (T1) and after orthodontic treatment (T2) were evaluated for differences in the change in tooth and root length of the maxillary incisors between both groups. Gender, treatment duration and age were examined as covariates.The mean values for root and tooth length of the maxillary incisors decreased by a range of 0.6 to 1.3 mm after orthodontic treatment. There was no significant difference between the groups for the majority of the measurements although there was a trend for less EARR in the SRA group. The maxillary left central incisor had significantly less proportional and non-proportional loss in tooth length in the SRA group. Age, gender and treatment duration were not associated with change in the proportional and non-proportional lengths for both groups.Patients with SRA did not exhibit a significant difference in the proportional and non-proportional change of length after orthodontic treatment when compared to the controls for most measurements. Only tooth length for the maxillary left central incisor had significantly less reduction after orthodontic treatment for both the proportional and non-proportional measurements in the SRA group compared to the control group.