Changes in the temporomandibular joint after mandibular setback surgery in monkeys: intraoral vertical versus sagittal split ramus osteotomy.
OBJECTIVE
This study was to investigate the changes in condylar position and structure of the temporomandibular joint (TMJ) after mandibular setback using 2 forms of the ramus osteotomy.


METHODS
Twelve adult male rhesus monkeys were randomly divided into groups A (n = 6) and B (n = 6) for mandibular setback surgical procedure. An intraoral vertical ramus osteotomy (IVRO) was performed in group A, whereas a sagittal split ramus osteotomy (SSRO) was performed in group B. Changes in condylar position were quantified by computed tomography (CT) preoperatively and postoperatively. All animals in groups A and B were killed at 12 weeks after surgical procedure. The TMJ specimens were harvested and processed for histological examination.


RESULTS
In group A, the CT examinations showed a significant anteroinferior displacement of the condyle after surgical procedure. In group B, slight posterior displacement and lateral tilting of the condyle were noted after surgical procedure. Thickened cartilage layer and endochondral ossification were seen in the condyles of group A, but only minimal alteration in articular cartilage was found in group B.


CONCLUSIONS
Both SSRO and IVRO can be biologically sound procedures for correction of mandibular prognathism. Intraoral vertical ramus osteotomy procedure leads to condylar adaptive remodeling, which may have favorable effects on TMJ, and it could be considered as a preferred surgical treatment for those patients with preoperative TMJ disorders.
Zhao
Qiang
Q
Key Laboratory of Biomedical Engineering, Sichuan University, Chengdu, Sichuan, China.
Hu
Jing
J
Wang
Dazhang
D
Zhu
Songsong
S
D000818:Animals; D000882:Haplorhini; D007091:Image Processing, Computer-Assisted; D008297:Male; D008334:Mandible / Q000601:surgery*; D008335:Mandibular Condyle / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D023421:Models, Animal; D010027:Osteotomy / Q000379:methods*; D011378:Prognathism / Q000601:surgery*; D011859:Radiography; D011897:Random Allocation; D013704:Temporomandibular Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*