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Temporal bone adaptations in response to protrusive function in juvenile and young adult rhesus monkeys (Macaca mulatta)

1984; Oxford University Press; Volume: 6; Issue: 3 Linguagem: Inglês

10.1093/ejo/6.3.155

1460-2210

Robert J. Hinton, J. A McNamara,

Amphibian and Reptile Biology

Temporal bone adaptations to protrusive function are described in both growing and non-growing animals. In juvenile monkeys fitted with a functional protrusive appliance, a discrete sequence of microanatomical changes in the temporal joint component is described. The most pronounced of these involved the deposition of new bone in the posterior region of the mandibular fossa (fossa roof and postglenoid spine). In a sequence which paralleled in time that of the condylar cartilage response to protrusion, new bone continued to be deposited in weeks 2–6 following appliance placement, was consolidated into layers in weeks 8–12, and had ceased by 24 weeks. The response in young adult animals was much more variable, possibly of reduced magnitude, and occurred at a slower pace. However, a response qualitatively similar to that in juveniles was observed in one-third of the experimental sample. It is suggested that the osteogenic response may be triggered by periosteal tension transmitted by fibres of the posterior portion of the articular disc. As skeletal adaptations reduce the need for habitual anterior posturing of the lower jaw by the lateral pterygoid muscles (after 8 weeks), tension in the disc fibres diminishes to levels present during normal jaw excursions and the stimulus for further osteogenesis is eliminated.