MEDLINE Journals

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

    Authors

    Liu ZJ, King GJ, Herring SW 

    Source

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

    Abstract

    PURPOSE
    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.
    RESULTS
    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.
    CONCLUSION
    An increased rate of mandibular distraction has significant negative effects on condylar morphology and microdensity.

    Mesh

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

    Language

    eng

    Pub Type(s)

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

    PubMed ID

    12905445

    Content Manager
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