title: Effect of clear aligner therapy on the buccolingual inclination of mandibular canines and the intercanine distance.
abstract: OBJECTIVE
  To compare the changes in buccolinugal inclination of mandibular canines and intercanine distance in patients treated with clear aligners to those treated with preadjusted edgewise appliances.
  
  
  METHODS
  The buccolingual inclination of mandibular canines and the intercanine distance were measured on pre- and posttreatment cone-beam computed tomograms of 30 patients who had been treated with clear aligners and 30 patients who had been treated with fixed preadjusted edgewise appliances. Differences between the aligner and fixed appliance groups and between pre- and posttreatment measurements were tested for statistical significance.
  
  
  RESULTS
  In both groups, most of the mandibular canines had positive buccolingual inclinations (ie, their crowns were positioned lateral to their roots) both before and after treatment. While there was no difference between the groups pretreatment, the posttreatment buccolingual inclination was significantly greater in the aligner group. In the fixed appliance group, the canines became more upright with treatment, while the buccolingual inclination did not change significantly in the clear aligner group. The intercanine distance did not differ between the groups either before or after treatment. However, it increased significantly over the course of treatment in the aligner group, whereas it did not change significantly in the fixed appliance group.
  
  
  CONCLUSIONS
  Orthodontic treatment with clear aligners tends to increase the mandibular intercanine distance with little change in inclination in contrast to treatment with fixed appliances, which leaves the intercanine distance unchanged but leads to more upright mandibular canines.
authors.affiliation: a  Assistant Professor, Division of Orthodontics, School of Dentistry, University of Minnesota, Minneapolis, Minn.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Grünheid
authors.affiliation: b  Dental Student, School of Dentistry, University of Minnesota, Minneapolis, Minn.
authors.forename: Sara
authors.initials: S
authors.lastname: Gaalaas
authors.affiliation: c  Dentist in Private Practice, Lakeville, Minn.
authors.forename: Hani
authors.initials: H
authors.lastname: Hamdan
authors.affiliation: d  Associate Professor and Director, Division of Orthodontics, School of Dentistry, University of Minnesota, Minneapolis, Minn.
authors.forename: Brent E
authors.initials: BE
authors.lastname: Larson
mesh_terms: D003481:Cuspid; D006801:Humans; D008310:Malocclusion / Q000628:therapy*; D008334:Mandible; D009967:Orthodontic Appliances
keywords: Aligner; Buccolingual inclination; Cone-beam computed tomography; Intercanine distance; Mandibular canine