Abstract
The importance of masticatory muscle function
on the growth and differentiation of condyle was
examined. The aim of this study was to investigate
how reduced masticatory muscle function influences
intrinsic regulatory factors which govern
growth and differentiation of condylar cartilage.
Masseter muscles of 3-week-old Wistar rats were
resected bilaterally. Masseteric resected animals
and corresponding control animals were sacrificed
at 3, 6, 12 and 21 days post-resection. The
condyles were then processed for histological
and immunohistochemical analysis. The expression
patterns of an inhibitory regulator (IL-1β) and
a master regulator (Sox9) of chondrogenesis in
condylar cartilage of growing rats were investigated.
Quantitative analysis shows that masseteric
resection significantly increased the number of
IL-1β positive cells in proliferative layer. In contrast,
the number of Sox9 positive cells was significantly
decreased compared to the control animals. It can
be concluded that the reduced articular function
due to masseteric resection decreased condylar
cartilage cell differentiation which led to the
decrease in the thickness of condylar cartilage.
