Changes in the condyle and disc in response to distraction osteogenesis of the minipig mandible.
OBJECTIVE
Distraction osteogenesis (DO) is a commonly used technique for mandibular lengthening, but changes in the temporomandibular joint have not been well documented. The purpose of this study was to evaluate the effect of DO, at varying rates, on the mandibular condyle and articular disc.


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/d for a 12-mm gap. After the animals were killed (0, 24, or 90 days), ipsilateral and contralateral condyles and discs were harvested and evaluated to determine changes in 1) condylar form and size, 2) condylar surface, and 3) the articular disc.


RESULTS
Articular surfaces of the condyles in control animals were smooth, with no irregularities or erosions. In animals undergoing distraction, ipsilateral condyles showed increasing changes in morphology and AP dimension, and surface contour irregularities as the DO rate increased. These changes were present, but to a lesser degree, in the contralateral condyles. Articular discs of both ipsilateral and contralateral sides showed variable thinning at the medial aspect at end DO. After 90 days, changes in the condyles and discs were reduced by remodeling except in the 4 mm/d DO groups.


CONCLUSIONS
Results of this preliminary study indicate that gross changes occur in condyles and discs after unilateral mandibular DO. These changes are more severe at faster distraction rates (4 mm/d) and tend to resolve during neutral fixation when a rate of 1 mm/d is used.
Thurmüller
Petra
P
Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital, Harvard School of Dental Medicine and Harvard Medical School, Boston, MA 02114, USA.
Troulis
Maria J
MJ
Rosenberg
Andrew
A
Kaban
Leonard B
LB
D000222:Adaptation, Physiological; D000818:Animals; D016723:Bone Remodeling; D005260:Female; D008334:Mandible / Q000601:surgery*; D019186:Mandibular Advancement / Q000379:methods; D008335:Mandibular Condyle / Q000473:pathology* / Q000502:physiology; D019647:Oral Surgical Procedures / Q000009:adverse effects*; D019857:Osteogenesis, Distraction / Q000009:adverse effects*; D013552:Swine; D013556:Swine, Miniature; D019224:Temporomandibular Joint Disc / Q000473:pathology* / Q000502:physiology; D013997:Time Factors