title: [Experimental study about osteotomy of mandibular outer cortex].
abstract: OBJECTIVE
  To investigate the change of morphology, biomechanics and histology after osteotomy of mandibular outer cortex.
  
  
  METHODS
  The mandibular outer cortex that involves angle and part of body was removed at one side in 8 minitype pigs aged 8-12 months. 2 pigs were selected randomly for histologic examination 12 weeks after operation. The other 6 animals were killed 24 weeks after operation. The thickness of new-formed mandibular outer cortex was measured and compared with that of operated side. Biomechanical test was performed in bilateral angles. Histological observation was made in the operated side.
  
  
  RESULTS
  The thickness of outer cortex was (2.1 +/- 0.3) mm and (2.5 +/- 0.4) mm in the operated side and opposite side, respectively, showing a significant difference between them (P < 0.01). The maximum load was (401.76 +/- 204.91) N and (585.42 +/- 413.07) N in the operated side and opposite side, respectively (P > 0.05). The Rigidity was (2172.19 +/- 1174.73) N/mm and (2363.90 +/- 1547.48) N/mm (P > 0.05). There was no statistical difference in biomechanics between the two sides. The histologic study showed histologically complete regeneration of outer cortex 24 weeks after mandibular outer cortex osteotomy.
  
  
  CONCLUSIONS
  After resection of mandibular outer cortex, the histologic restoration is complete, but the new-formed outer cortex is thinner with local depression. Bone tubercle can be seen at the angle after bone regeneration. There is no obvious change in biomechanics after outer cortex osteotomy.
authors.affiliation: Department of Maxillofacial Surgery, Dalian City Central Hospital, Dalian 116033, China.
authors.forename: Yan-Feng
authors.initials: YF
authors.lastname: Zhao
authors.forename: Lai
authors.initials: L
authors.lastname: Gui
authors.forename: Ping
authors.initials: P
authors.lastname: Lu
authors.forename: Xiao-Nan
authors.initials: XN
authors.lastname: Zhou
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D005260:Female; D008297:Male; D008334:Mandible / Q000601:surgery*; D010027:Osteotomy / Q000379:methods*; D013552:Swine; D013556:Swine, Miniature