The Effect Of Class â…¢ Inter-maxillary Orthopedic Force On The Position And Sutures Of Maxilla: An Animal Experimental Study

Angle's Class Ⅲ malocclusion is common in orthodontic clinics, which severely degrade the craniofacial development, oral function and facial aesthetics. Orthopedics force is commonly used to correct skeletal abnormality at early stage, and the orthopedic mechanism is the primary subject for the researchers. The forward growth of maxilla affected by orthopedic force may play important role in the correction of class III skeletal abnormality. Specially, for those abnormalities with deficient growth in the maxilla, the protrusion of maxilla is the main therapy subject. But in the orthopedic therapy, what happened in maxilla? Did maxillary sutures participated in the growth remolding? How did the maxillary sutures remodel? Is the orthopedic force safe for clinic use? All the questions are not solved yet.[Material and method] The animal model on pubescent Rhesus monkey was established in our study by the use of TMA Ⅲ. Lateral cephalograms was taken to observe the maxillary development in different stages. Histological method (HE staining) and histomorphometric technology were used to observe the changes in maxilla. In situ hybridization was employed to detect the expression of TGF-β1 mRNA.[Results and conclusion ] (1) Under class Ⅲ inter-maxillary orthopedic force, the maxillary position of test group were markedly forward changed and the maxillary length increased. (2)During the treat period, relative changes of cellular density and suture width were observed in test groups. (3) In different treat period, the expression intensities of TGF- β 1 were significant in different sutures. Three months group expressed more intensely than in six months group, which indicated that the remolding in three months group was more actively than in six months group. Maybe, TGF-βl participated in the regulationof the maxillary sutures' adapted remodeling through multiple approaches. (4)Our study proved that the proper inter-maxillary orthopedic force accelerated the remodeling of maxilla and no pathological changes were found. The orthopedics treatment of maxilla is safe and effective.