External Root Resorption after Orthodontic Treatment with Invisalign®: A Retrospective Study

AIM- To measure the incidence and severity of root resorption after orthodontic treatment with Invisalign. MATERIAL AND METHODS- This retrospective study was conducted at Riyadh, Saudi Arabia from June 2017 to January 2018. Pre- treatment and post-treatment Orthopantographs were obtained from orthodontic records of 29 patients managed with aligners (Invisalign®, Align Technologies, Santa Clara, CA, USA) at different dental clinics in Riyadh City. The selected sample was fulfilled the following criteria- (1) Class I malocclusion, (2) Mild to moderate crowding, (3) Non-extraction orthodontic treatment, (3) No evidence of root resorption before orthodontic treatment, (4) No root abnormalities or dilaceration, and (5) Good quality of pre- and post-treatment Orthopantographs. One examiner performed the measurements directly on the Orthopantographs using electronic digital caliper (Mitutoyo Manufacturing Co. Ltd., Tokyo, Japan) with an accuracy of 0.01mm. The measurements were performed on maxillary and mandibular central incisors, lateral incisors, and canines pre- and post-operatively, resulting in a total of 696 measurements. The crown length was measured from incisal edge to cemento- enamel-junction, while the root length from cemento-enamel-junction to root apex. RESULTS- In our study, 72% of the teeth demonstrated root resorption, in regard to the severity of root resorption, we found that mild root resorption > 0% up to 2% in all the affected teeth. Upper Anterior teeth have more significant resorption rate than lower anterior teeth P<0.05. CONCLUSION- The present study showed that incidence of root resorption was high after orthodontic treatment with Invisalign®, however the severity is very low and it is limited to the surface resorption only.