Abstract: Objective  To explore the mechanism of phospholipase C-γ1(PLC-γ1) in cartilage ossification of the posterior condyle of rats after functional mandibular protrusion. 
Methods  Sixty four-week-old male Sprague-Dawley(SD) rats were adaptively fed for one week. The mandibular protrusion model of SD rats was established, and then the rats were divided into experimental group and control group equally and randomly. The experimental group was treated with self-made inclined plane appliance for mandibular protrusion(24 h /d), while the control group was not treated. Five rats in each group were sacrificed at 1, 3, 7, 14, 21, 28 d respectively after using inclined plane appliance. The bilateral condyles were fixed, decalcified, dehyded, and then embedded. The histological changes of the paraffin sections were observed by HE staining, and the expression of PLC-γ1 in posterior condylar cartilage was detected by immunohistochemistry combined with image analysis. 
Results  The IHS value of PLC-γ1 expression in the posterior condyle cartilage of the experimental group was higher than that in the control group at 7, 14, 21, 28 d, and the difference was statistically significant(P＜0.05). The IHS value of PLC-γ1 expression was not significantly different between two groups at different time points(P＞0.05). 
Conclusion  PLC-γ1 may be involved in the process of condylar cartilage ossification of rats after functional mandibular protrusion, and the detection of its level has important reference value for the study of cartilage ossification in condylar process.

Key words: mandibular diseases, cartilage ossification, phospholipase C-γ1