Abstract: Objective: To investigate the expression of connective tissue growth factor (CTGF) in rat mandibular condylar cartilage during functional mandibular forward positioning with immunohistochemical staining. Methods: 45 five-week-old female Sprague-Dawley (SD) rats were randomly divided into five experimental groups (n=25) and five control groups (n=20). The animals in the experimental groups were fitted with modified removable acrylic inclined planes to advance the mandible, while rats in the normal control groups were left intact. The rats were sacrificed on day 3, 7, 14, 21, and 30, respectively, to assess the expression of CTGF with immunohistochemical staining. Results: When compared with the proliferative zone of the same age in the control and experimental groups, higher expression of CTGF was observed in the hypertrophic zone of posterior part of condylar cartilage (P<0.05) . The expression of CTGF in the proliferative zone of posterior part of condylar cartilage in the control groups did not show significant differences during the experiment period, and the hypertrophic zone displayed the same pattern. However, compared with those of the age-matched controls, the positive signals of CTGF in the proliferative zone and hypertrophic zone of the experimental animals were significantly stronger on day 7, 14, and 21, respectively (P<0.05), whereas no statistical differences were found on days 3 and 30. Conclusion: CTGF expression in mandibular condylar cartilage is induced by the mechanical compressive stimuli in vivo. As a cytokine, CTGF may mediate the morphological changes induced by mechanical stimuli in condylar cartilage.

Key words: Connective tissue growth factor, Condylar cartilage cells, Mandibular forward positioning