title: An orthodontic technique for minimally invasive extraction of impacted lower third molar.
abstract: OBJECTIVE
  To present a novel orthodontic approach for minimally invasive extraction of impacted mandibular third molars (M3s) close to the inferior alveolar nerve (IAN).
  
  
  METHODS
  Eight patients (8 M3s) requiring extraction of M3s were included in this study; there were 2 cases of horizontal impaction, 4 of mesioangular impaction, and 2 of vertical impaction. Cone-beam computed tomogram showed that the roots of impacted M3s in 2 cases interrupted the cortices of the mandibular canal, and those in the other 6 cases were very close to the IAN. Orthodontic treatment was performed in this study. The crowns of 5 impacted teeth were surgically exposed before the application of the orthodontic device, whereas bonding was performed directly to the occlusal surface of the other 3 M3s, which had partially erupted. The opposing maxillary M3s were removed in 3 cases. One-step orthodontic extraction was applied to vertically impacted M3s and 2-step treatment was applied to horizontally or mesioangularly impacted M3s. Success was defined as the separation of the impacted tooth from the IAN as visualized on cone-beam computed tomogram.
  
  
  RESULTS
  After orthodontic treatment, all impacted M3s were extruded and separated from the IAN (mean, 6.6 months; range, 4 to 10 months), without any neurologic consequences. The average time of extraction was 5 minutes. In all 8 cases, new bone formation occurred distal to the adjacent second molar.
  
  
  CONCLUSIONS
  This orthodontic technique may be a minimally invasive approach for the extraction of impacted M3s adjacent to the IAN, with a decreased risk of paresthesias and with osteoperiodontal advantages.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Shanghai Ninth People's Hospital affiliated with Shanghai Jiaotong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China.
authors.forename: Zhi-Gui
authors.initials: ZG
authors.lastname: Ma
authors.forename: Qian-Yang
authors.initials: QY
authors.lastname: Xie
authors.forename: Chi
authors.initials: C
authors.lastname: Yang
authors.forename: Guang-Zhou
authors.initials: GZ
authors.lastname: Xu
authors.forename: Xie-Yi
authors.initials: XY
authors.lastname: Cai
authors.forename: Jie-Yan
authors.initials: JY
authors.lastname: Li
mesh_terms: D000328:Adult; D054893:Cone-Beam Computed Tomography; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible; D008340:Mandibular Nerve / Q000000981:diagnostic imaging; D019060:Minimally Invasive Surgical Procedures; D008964:Molar, Third / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D050793:Orthodontic Extrusion / Q000295:instrumentation / Q000379:methods*; D014081:Tooth Extraction / Q000295:instrumentation / Q000379:methods*; D014095:Tooth, Impacted / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D055815:Young Adult