OBJECTIVETo investigate the expression of TGF-beta 1 mRNA in pubescent Rhesus monkeys' condylar under Class III intermaxillary functional orthopedic force for different lengths of time.

METHODSSix pubescent Rhesus monkey were divided into two test groups and a control group. Monkeys in the test groups were TMAIII while the control groups did not. Histological method (HE staining) and in situ hybridization were employed in this study.

RESULTS1. The histological results showed that, compared with the control group, the anterior part of the condyle became thicker while the median part and the posterior part became thinner in 3 months group. However, in 6 months group, the change was similar to 3 months group. 2. The results of in situ hybridization showed that, in control group, TGF-beta 1 mRNA mildly expressed in the anterior part of the condyle while extensively in the median and posterior parts. In 3 months group, TGF-beta 1 mRNA expressed in all parts of condyle; the most intensive expression was in the anterior part. Compared with 3 months group, the expression of TGF-beta 1 mRNA decreased in 6 months group, but the expression in anterior part was stronger than in median and posterior parts.

CONCLUSIONUnder Class III Orthopedic therapy, TGF-beta 1 mRNA probably participated in the endochrondral bone remodeling in the condyle, and the expression was closely related to loading time. In 3 months group, the expression of TGF-beta 1 mRNA was stronger than that in 6 months group. It was inferred that the remodeling of endochrondral bone was more active in 3 months group.