Abstract
BackgroundThe pathogenesis of traumatic TMJ ankylosis remains unclear. This study aimed to verify the role of the lateral pterygoid muscle in the pathogenesis of traumatic temporomandibular joint (TMJ) bony ankylosis.MethodsEight 6-month-old male sheep were used in this study. Bilateral TMJ osteotomies were performed to induce sagittal fractures of the mandibular condyle. The lateral one-fourth segment of the disc was removed to establish a model of TMJ bony ankylosis. Subsequently, the function of the left and right lateral pterygoid muscles was blocked (experimental group) or maintained (control group), respectively. At 12 weeks postoperatively, animals were sacrificed and TMJ complex samples were evaluated by gross observation, spiral computed tomography (CT), micro-CT, and histological examinations.ResultsGross observation revealed bony ankylosis in the control TMJs and fibrous adhesions in the experimental TMJs. Spiral CT and micro-CT demonstrated that, compared to the experimental group, the control group showed calcified callus formation in the joint space and roughened articular surfaces after new bone formation, which protruded into the joint space. Maximum mediolateral and anteroposterior condylar diameters were significantly larger in the control group than in the experimental group. Micro-CT also showed that the primary growth orientation of new trabeculae was consistent with the direction of lateral pterygoid traction in the control group, but not in the experimental group. Histological examination showed fibro-osseous ankylosis in the control group, but not in the experimental group.ConclusionsThe lateral pterygoid simulates the effects of distraction osteogenesis, which is an important factor in the pathogenesis of TMJ bony ankylosis during the healing of sagittal condylar fractures.
Highlights
The pathogenesis of traumatic temporomandibular joint (TMJ) ankylosis remains unclear
TMJ bony ankylosis at the lateral articular surface and Y-shaped bifid condyles could be observed by the naked eye during dissection (Fig. 2a)
We found that blockade of the function of the lateral pterygoid muscle prevented the development of traumatic TMJ bony ankylosis, while maintaining the function of this muscle successfully established an animal model of traumatic TMJ bony ankylosis
Summary
This study aimed to verify the role of the lateral pterygoid muscle in the pathogenesis of traumatic temporomandibular joint (TMJ) bony ankylosis. Temporomandibular joint (TMJ) ankylosis is characterized by stiffening of the joint due to abnormal adhesion and rigidity of the relevant bones after injury or disease. This condition has significant effects on physical and mental health and results in a poor quality of life, with. In 1982, Rowe found that TMJ ankylosis can result from SFMC [10], while Duan et al reported that type III sagittal fractures were associated with disc displacement, indicating a high risk of TMJ ankylosis [11]. The relationship between traction of the lateral pterygoid muscle and traumatic TMJ ankylosis is not well understood
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