Apical root resorption during orthodontic treatment with aligners? A retrospective radiometric study

Abstract

IntroductionObjective of this study was to investigate the incidence and severity of apical root resorptions (ARR) during orthodontic treatment with aligners.Materials and methodsThe sample comprised 100 patients (17–75 years of age) with a class I occlusion and anterior crowding before treatment, treated exclusively with aligners (Invisalign®, Align Technologies, Santa Clara, CA, USA). The following teeth were assessed: upper and lower anterior teeth and first molars. Root and crown lengths of a total of 1600 teeth were measured twice in pre- and post-treatment panoramic radiographs. Afterwards, relative changes of the root length during treatment were calculated by a root-crown-ratio taking pre- and post-treatment root and crown lengths into consideration. A reduction of this ratio was considered as a shortening of the initial root length. Additionally, tooth movements of the front teeth were assessed by lateral cephalograms and the 3-dimensonal set up of each patient.ResultsAll patients had a reduction of the pre-treatment root length with a minimum of two teeth. On average 7.36 teeth per patient were affected. 54% of 1600 measured teeth showed no measurable root reduction. A reduction of >0%-10% of the pre-treatment root length was found in 27.75%, a distinct reduction of >10%-20% in 11.94%. 6.31% of all teeth were affected with a considerable reduction of >20%. We found no statistically significant correlation between relative root length changes and the individual tooth, gender, age or sagittal and vertical orthodontic tooth movement; except for extrusion of upper front teeth, which was considered as not clinical relevant due to the small amount of mean 4% ARR.ConclusionsThe present study is the first analyzing ARR in patients with a fully implemented orthodontic treatment with aligners (i.e. resolving anterior crowding). The variety was high and no clinical relevant influence factor could be detected. A minimum of two teeth with a root length reduction was found in every patient. On average, 7.36 teeth per patient were affected.

Root resorption during orthodontic treatment with Invisalign®: a radiometric study

“…These values are consistent with those reported by Krieger et al [31] with a minimal RR ranged from 25 to 32%, mild RR from 11 to 18%, and severe RR from 1 to 14% for mandibular incisors.…”

Root Resorption in Mandibular Incisors During Orthodontic Treatment with Invisalign®: A Radiometric Study

“…These values are consistent with those reported in a retrospective study of Krieger et al (29) who examinated the incidence and severity of RR in patients who underwent a fully implemented orthodontic treatment with aligners: 46% of all teeth presented RR; in particular mandibular incisors showed a minimal RR ranged from 25% to 32%, mild RR from 11% to 18% and severe RR from 1% to 14%.…”

“…On the basis of Krieger et al, Fritz et al and Linge and Linge, all root and crown measurements were assessed by one examiner blinded in a stochastic sequence (11,29,30). To evaluate the pre-and post-treatment root length a symmetric cross was defined by two connecting lines: the first from the width of the incisal edge of the tooth to the apex, the second from the mesial and distal edge of cementoenamel-junction.…”

The clinical efficacy of deproteinized bovine bone mineral with 10% collagen in conjunction with localized piezosurgical decortication enhanced orthodontics: A prospective observational study

“…To compensate, the relationship between the vertical root length and crown length was used for examination. This technique has been described in another investigation . Taking under consideration the pre‐ and post‐treatment root and crown lengths, the individual root‐crown‐ratio (RCR) was calculated for each tooth and, therefore, the relative changes of RCR (rRCR).…”