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B. Ma, Wayne J. Sampson, O. W. Wiebkin, D. F. Wilson, N. L. Fazzalari
Trabecular anisotropy and collagen fibre orientationin the mandibular condyle followingexperimental functional appliance treatmentusing sheep
Keywords: Sheep mandibular condyle, growth modification, collagen fibre orientation, trabecular anisotropy
In order to study the modifying effects of functional applianceson the mechanical environment of the temporomandibularjoint (TMJ), we characterised the structureof the mandibular condyle subsequent to an experimentalfunctional appliance intervention. Eight,four-month-old, castrated male Merino sheep, wererandomly allocated to experimental and control groups(n = 4 in each group). Forward mandibular displacementwas induced with an intraoral appliance. Thestudy period was 15 weeks, during which time fluorochromeswere administered to all of the animals. Midsagittalsections of the TMJ were selected for analysisand trabecular anisotropy was estimated using bonehistomorphometry. Only the experimental group demonstratedthat the trabecular bone in the central condylarregion was less anisotropic when compared to thesubchondral region. Also, the variation in trabecularanisotropy of the central condylar region was found tobe smaller in the experimental group. The collagenfibre orientation was analysed under polarised light asthe proportion of the dark or bright fibres observed inregions which existed before, and regions which formedduring the experiment, as determined by the fluorochromelabels. In the experimental group, more brightcollagen fibres were found in the most superior regionof the mandibular condyle when compared with thecontrols. These results suggested that the experimentalfunctional appliances changed the orientation and patternof the mechanical forces acting on the mandibularcondyle, and possibly increased the magnitude of thelateral functional forces applied to the most superiorpart of the condyle during such treatments.
Veterinary and Comparative Orthopaedics and Traumatology, Schattauer
Print ISSN: 0932-0814
Volume: 19
Pages: 35 - 42