title: Total reconstruction of mandible by transport distraction after complete resection for benign and malignant tumors.
abstract: BACKGROUND
  Distraction osteogenesis (DO) is a recognized technique for the bone lengthening and correction of various mandibular deformities. It has an aided advantage of both osteogenesis and histiogenesis in achieving a bone supported mandibular ridge covered with attached gingiva, forming an appropriate vestibule.
  
  
  OBJECTIVE
  The aim of this study was to present our clinical experience in using transport DO technique (TDO) for treating mandibular bony defects following tumor ablation in both benign and malignant tumor cases.
  
  
  METHODS
  This is a retrospective analysis of patients who underwent mandibular TDO for the correction of mandibular segmental defect at authors' center from 2000 to 2014 with the inclusion criteria of segmental bony defect in the mandible with moderate soft tissue defect. After the latency period of 10 days, the distraction was initiated at a rate of 0.25-1 mm/day. The distraction period continued until the segment with the transport disc reached the distal base. The total consolidation periods ranged from 6 to 14 weeks.
  
  
  RESULTS
  The study group consists of 9 cases of TDO for reconstruction of segmental defect following tumor resection, of which 5 cases of benign and 4 cases of malignant tumor resection. The mean (standard deviation [SD]) bony defect length was 48 mm (9.8). The mean (SD) distracted bone lengthening was 43 mm (9.7), with a mean (SD) consolidation period of 17.9 (3.4) weeks. The bony defect involved the hemimandibular angle in four patients, hemimandibular body in three patients, with greater involvement of the body, symphysis in two patients, and of the bilateral mandibular body in two patients. Except for two patients who required additional bone grafting to complete union with the residual bone, other seven patients in the distraction zone showed the complete ossification by radiological evaluation. The mean (SD) consolidation period of 13.56 (1.5) weeks ranging from 12-15 weeks with the mean (SD) follow-up years is about 8.7 years (2.95) for the cases. Out of the 9 cases, one case had recurrence in the follow-up period and underwent resection with reconstruction using reconstruction plate in the created bone. The overall success rate of TDO was 88.9% (8 out of 9) in spite of adequate case selection and TDO protocol.
  
  
  CONCLUSIONS
  TDO potentially benefits patients with segmental bony defects following tumor ablation in mandible. It is an unswerving tool to achieve sufficient bone in mandible in patients who cannot undergo aggressive surgery or poor general health. Bone resorption remains a critical issue for this reconstruction technique, though blood supply is continuously maintained in TDO.
authors.affiliation: Director and Consultant, Balaji Dental and Craniofacial Hospital, Chennai, Tamil Nadu, India.
authors.forename: S M
authors.initials: SM
authors.lastname: Balaji
mesh_terms: D000368:Aged; D016025:Bone Transplantation; D005260:Female; D006801:Humans; D008297:Male; D008339:Mandibular Neoplasms / Q000601:surgery*; D063175:Mandibular Reconstruction; D008875:Middle Aged; D019857:Osteogenesis, Distraction; D012189:Retrospective Studies; D016896:Treatment Outcome