Condylar Resorption Following Compressive Mechanical Stress in Rabbit Model - Association of Matrix...

Area of Science:

• Orthodontics and Maxillofacial Surgery
• Biomechanical Engineering
• Skeletal Biology

Background:

• Idiopathic condylar resorption (ICR) is a condition affecting the condylar head, often occurring after orthodontic or orthognathic procedures.
• ICR can lead to relapse in patients undergoing mandibular treatment.
• Understanding the mechanism of ICR is crucial for preventing post-treatment complications.

Purpose of the Study:

• To investigate the mechanism by which condylar resorption influences compressive mechanical stress in the temporomandibular joint.
• To evaluate the effects of mandibular advancement on condylar head morphology and cellular activity.
• To elucidate the role of specific matrix metalloproteinases (MMPs) in condylar degradation.

Main Methods:

• Mandibular osteotomy and advancement (3.5 mm) were performed on 15 rabbits.
• Micro-computed tomography, histological staining (TRAP), and immunohistochemistry (MMP-3, MMP-13) were used for analysis.
• Samples were analyzed at one and two weeks post-surgery.

Main Results:

• Significant increases in the area and depth of anterior condylar resorption were observed at two weeks compared to one week.
• Tartrate-resistant acid phosphatase (TRAP)-positive cells, indicative of osteoclast activity, were significantly higher at two weeks.
• High levels of MMP-3 and MMP-13 were detected in the condylar head cartilage, suggesting active degradation.

Conclusions:

• Compressive mechanical stress from mandibular advancement induces bone resorption on the anterior condylar surface.
• This process is associated with increased osteoclast activity and the upregulation of MMP-3 and MMP-13.
• These findings highlight a mechanism for ICR and cartilage degradation in the temporomandibular joint following mandibular repositioning.