title: Microscopic changes in the condyle and disc in response to distraction osteogenesis of the minipig mandible.
abstract: OBJECTIVE
  Unilateral mandibular distraction osteogenesis (DO) has been shown to cause gross changes in the mandibular condyle and articular disc. The purpose of this study was to correlate histologic findings with these gross changes in a minipig distraction model.
  
  
  METHODS
  Semiburied distractors were placed via submandibular incisions in 15 minipigs. Two unoperated animals served as controls. The protocol consisted of 0-day latency and rates of 1, 2, or 4 mm/day for a 12-mm gap. After the minipigs were killed (at 0, 24, or 90 days), ipsilateral and contralateral condyles and discs were harvested, decalcified, prepared for standard paraffin embedding, and evaluated to determine changes in 1) morphology and thickness of the articular cartilage and subchondral bone and 2) morphology of the disc.
  
  
  RESULTS
  In control animals, there were no degenerative changes in the articular cartilage and underlying condylar bone; there were no significant differences in the mean articular cartilage thickness. The temporomandibular joint discs were normal. In experimental animals, distracted condyles showed increasing degenerative changes and mean articular cartilage thickness as the DO rate increased. The discs were thinner. These changes were present, but to a lesser degree, in the contralateral condyles. After 90 days, degenerative changes in the condyles and discs were reduced, after remodeling, except in the 4 mm/day DO group.
  
  
  CONCLUSIONS
  Histologic changes in the condyles and temporomandibular joint discs in response to mandibular DO correlated with previously reported gross changes. These changes were greater at higher distraction rates and remodeling back to normal occurred in mandibular condyles distracted at 1 mm/day.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital, Harvard School of Dental Medicine, and Harvard Medical School, Boston, MA 02114, USA.
authors.forename: Petra
authors.initials: P
authors.lastname: Thurmüller
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Troulis
authors.forename: Andrew
authors.initials: A
authors.lastname: Rosenberg
authors.forename: Sung-Kiang
authors.initials: SK
authors.lastname: Chuang
authors.forename: Leonard B
authors.initials: LB
authors.lastname: Kaban
mesh_terms: D000818:Animals; D002356:Cartilage / Q000033:anatomy & histology; D005260:Female; D008334:Mandible / Q000601:surgery*; D008335:Mandibular Condyle / Q000033:anatomy & histology*; D019857:Osteogenesis, Distraction / Q000379:methods*; D013552:Swine; D013556:Swine, Miniature; D019224:Temporomandibular Joint Disc / Q000033:anatomy & histology*