title: Midline correction by asymmetric reciprocal torque: a pilot study.
abstract: OBJECTIVE
  Can we correct dental midline discrepancies by systematic torque bends on all canines and premolars without extraction and mesiodistal tooth movement?
  
  
  METHODS
  Eight orthodontic patients (4 males, 4 emales, mean age 31 years) presented a dental midline discrepancy of 2-4 mm, moderate deviation of the chin, no skeletal asymmetry, and a horizontal orientation of the occlusal plane in the frontal aspect. On the side where the mandible was shifted medially, asymmetric torque bends moved the antagonist canine and both premolar crowns buccally, while palatal crown torque was used on the maxillary canine and premolars on the other side. Lingual crown torque corrected the medially shifted canine and premolars in the mandibular dental arch, and buccal crown torque the laterally shifted lower canine and premolars.
  
  
  RESULTS
  On average, torque effects altered the canine guidance by 6.5 ± 4.7°, the first premolar guidance by 7 ± 4.1°, and the second premolar guidance by 6.3 ± 3.7°. Correction of the dental midline shift averaged 1.6 ± 0.8 mm after the torque, and eliminated the midline discrepancy completely (n = 2) or partly (n = 6).
  
  
  CONCLUSIONS
  In this pilot study, asymmetric reciprocal torque represented a treatment option for midline corrections of approximately 2-4 mm and improvement in the chin position without mesiodistal tooth movement or extraction.
authors: Department of Craniofacial Growth and Developmental Dentistry, Research Institute of Occlusion Medicine, Research Center of Brain and Oral Science, Division of Orthodontics, Kanagawa Dental College, Yokosuka, Japan.
authors: Kanji
authors: K
authors: Onodera
authors: Aleš
authors: A
authors: Celar
mesh_terms: D000293:Adolescent; D000328:Adult; D001641:Bicuspid; D003481:Cuspid; D005146:Facial Asymmetry / Q000175:diagnosis / Q000628:therapy*; D005260:Female; D005459:Fluorides; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008312:Malocclusion, Angle Class II / Q000628:therapy*; D003765:Models, Dental; D009969:Orthodontic Wires; D009971:Orthodontics, Corrective / Q000379:methods*; D010865:Pilot Projects; D011862:Radiography, Panoramic; D013706:Temporomandibular Joint Dysfunction Syndrome / Q000175:diagnosis / Q000628:therapy; D014081:Tooth Extraction; D014087:Tooth Movement Techniques; D019415:Torque; D014520:Urethane; D055815:Young Adult
chemical_list: C073962:Orthodontic Cement VP 862; D014520:Urethane; D005459:Fluorides