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

Head Face Med. 2013 Aug 14:9:21. doi: 10.1186/1746-160X-9-21.

Abstract

Introduction: Objective of this study was to investigate the incidence and severity of apical root resorptions (ARR) during orthodontic treatment with aligners.

Materials and methods: The 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.

Results: All 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.

Conclusions: The 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.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Female
  • Humans
  • Incidence
  • Male
  • Malocclusion / diagnostic imaging
  • Malocclusion / therapy*
  • Middle Aged
  • Orthodontic Appliances / adverse effects*
  • Radiography, Panoramic
  • Radiometry / methods*
  • Retrospective Studies
  • Root Resorption / diagnostic imaging
  • Root Resorption / etiology*
  • Tooth Root / diagnostic imaging*
  • Young Adult