Evaluation of the Stability after Surgical–Orthodontic Correction of Skeletal Open-Bite with Mandibular Counterclockwise Rotation using Modified Inverted L Osteotomy

  • Dr Zaher Aymach, Tohoku University, Japan
  • Dr Jyunichi Hara, Tohoku University,Graduate school of Dentistry,Department of maxillofacial surgery and orthognathics, Japan
  • Dr Hitoshi Nei, Tohoku University,Graduate school of Dentistry,Department of maxillofacial surgery and orthognathics, Japan
  • Prof Hiroshi Kawamura, Tohoku University,Graduate school of Dentistry,Department of maxillofacial surgery and orthognathics, Japan
  • Prof Junji Sugawara, Department of Orthodontics ,school of Dentistry ,University of Connecticut USA, Japan

Introduction: Surgical-orthodontic treatment for skeletal open bite is among the most challenging for both orthodontists and surgeons. Correcting the open bite with a mandible-dependent surgery and counterclockwise rotation reported to increase the posterior facial height and to stretch the associated muscles and ligaments, leading to less stability and subsequent relapse. Therefore, maxillary impaction was frequently included in the treatment plan.
In our university, we are demonstrating Modified Inverted L ostetotomy (M-ILO) that allows stable mandibular counterclockwise rotation with respect to anatomical structures.
Purpose: The purpose of this study is to evaluate the stability of skeletal open bite treated with M-ILO.
Materials and methods: In a retrospective prospect, we included 12 patients with skeletal open bites (8 femals, 4 males) who received mandibular M-ILO in the period 2004-2007 at Tohoku University Hospital. Lateral cephalograms were taken immediate before surgery T1, immediate post surgey T2, and at 1 year after surgery T3. Cephalometric analysis with reference to Nasion and SN were obtained for Pogonion, Menton and mandibular plane angle at the designated spans.
Results: Mandibular counterclockwise rotation showed stability for Pg and Me points referred linearly to Nasion .However, mandibular plane angle showed increase at T3 compared to T2.Statistically the increase wasn’t significant between the two times.
Conclusion: Skeletal open bite can be successfully treated using M-ILO. Mandibular counterclockwise rotation showed stability at one year after surgery. However, further evaluation will be needed at a long term. The collaboration between orthodontists and surgeons is highly ensured for maintaining treatment progress.