MEDLINE Journals

    Alterations of morphology and microdensity in the condyle after mandibular osteodistraction in the rat.


    Liu ZJ, King GJ, Herring SW 


    J Oral Maxillofac Surg 2003 Aug; 61(8) :918-27.


    In this study, we examined the effects of mandibular distraction osteogenesis on the morphology and the microdensity of the rat condyle. Materials and Methods: One hundred twenty-nine rats were allocated to 4 experimental groups (n = 32 or 33). Each received unilateral mandibular ramus osteotomy and distraction device placement. After a 3-day latency, these were distracted once a day for 5 days. The slow distraction group was distracted a total of 1 mm (0.2 mm/d); the moderate group, 2 mm (0.4 mm/d); the rapid group, 3 mm (0.6 mm/d); and the sham group, no distraction (0.0 mm/d). Eight to 9 rats in each group were sacrificed at each of 4 time points after device placement (6, 10, 24, and 38 days). Baseline data were obtained 3 days after osteotomy and device placement without distraction from an additional 10 rats. Radiographs of the hemimandibles were scanned and measured to evaluate changes in condylar size (height, width, and area), angulation, and bone microdensity converted to equivalent bone thickness using a stepwedge. The wet weights of masseter muscle were measured at the time of harvest.
    1) Muscle weight gains over time were significantly lower in the treated than the untreated sides throughout the consolidation period (P <.001). 2) Condylar size and angulation on the untreated side increased postoperatively, whereas there was a significant reduction of these parameters (P <.01 to.001) on the treated side at 24 and/or 38 days. 3) Condylar microdensity significantly increased on the untreated side at 24 and 38 days (P <.05 to.01) but not on the treated side. 4) Faster or larger distraction caused more severe size reduction and more upright condylar angulation, prevented an increase in bone microdensity on the treated side, especially during the consolidation periods (P <.05 to.01), and retarded increase in muscle weight, whereas a slower distraction rate showed few negative, and even some positive effects. 5) Correlations in size, angulation, and microdensity between right and left condyles became less significant over time. 6) There were positive correlations between muscle weight and condylar size, angulation, and microdensity.
    An increased rate of mandibular distraction has significant negative effects on condylar morphology and microdensity.


    Analysis of Variance
    Bone Density
    Mandibular Condyle
    Masseter Muscle
    Matched-Pair Analysis
    Organ Size
    Osteogenesis, Distraction
    Random Allocation
    Rats, Sprague-Dawley
    Time Factors



    Pub Type(s)

    Journal Article Research Support, U.S. Gov't, P.H.S.

    PubMed ID


    Content Manager
    Related Content

    Effect of distraction rate and consolidation period on bone density following mandibular osteodistraction in rats.

    Trabecular organization in mandibular osteodistraction in growing and maturing rats.

    Changes in parathyroid hormone-related protein and 3-dimensional trabecular bone structure of the mandibular condyle following mandibular distraction osteogenesis in growing rats.

    Changes in growth and morphology of the condyle following mandibular distraction in minipigs: overloading or underloading?

    Primary study of the use of a shape-memory alloy distraction device in the dog mandible for alveolar ridge distraction: determination of osteotomy techniques and evaluation of osteogenesis outcome.

    Condylar cartilaginous changes after mandibular distraction osteogenesis in rabbits.

    Sequential histomorphometric analysis of regenerate osteogenesis following mandibular distraction in the rat.

    Proliferation of masseter myocytes after distraction osteogenesis of the porcine mandible.