OBJECTIVEThe purpose of the study is to detect the expression of TGF-beta1 mRNA in the maxillary sutures of puberty rhesus during different periods of the loading of intermaxillary class III orthopedic force.

METHODSThe animal model was established with 6 puberty female rhesus, which were randomly divided into experimental group (wearing class III twin-block magnet appliance, each 2 rhesus for 3 and 6 month respectively) and control group (not wearing any appliance, each 1 rhesus for 3 and 6 month respectively). Tissue sections were obtained perpendicular to the sutures. In situ hybridization was used to the expression of TGF-beta1 mRNA, and the expression intensity was measured and statistics was performed by SPSS 11.0.

RESULTSThere were no statistic differences of cellular density between palatomaxillary suture in vertical group and pterygomaxillary suture in horizontal group, but statistic differences were found between other groups. The expression of TGF-beta1 mRNA was detected in the control group, but the expression intensity was obviously increased after the load of intermaxillary class III orthopedic force. Statistically significant differences were found among all groups except the six months experimental group and control group of temporozygomatic sutures and pterygomaxillary sutures. Experimental groups were more intensive than the control group and three months group was more intensive than the six months group.

CONCLUSIONThe active tissue remodeling happened in the circummaxillary sutures by the effect of class III intermaxillary orthopedic force. Cell proliferation, extracellular matrix synthesis and bone formation were accelerated. During the different remodeling periods, the expression intensities were different, which may be related to the different force loading manners, the different reaction of sutures to the orthopedic force and the different biological function of TGF-beta1 in the different periods.