The correlation between neovascularization and bone formation in the condyle during forward mandibular positioning.

Area of Science:

• Orthodontics
• Developmental Biology
• Regenerative Medicine

Background:

• Understanding condylar growth mechanisms is crucial for treating mandibular deficiencies.
• Functional appliance therapy aims to modify mandibular growth, but cellular responses require detailed investigation.

Purpose of the Study:

• To investigate the temporal expression of Vascular Endothelial Growth Factor (VEGF) and new bone formation in the mandibular condyle during forward positioning.
• To compare vascularization and bone growth during natural condylar development versus induced growth via forward mandibular positioning.

Main Methods:

• Utilized Sprague-Dawley rats, with 100 fitted with a bite-jumping appliance and 50 controls.
• Analyzed sagittal sections stained for VEGF and new bone formation (PAS) across multiple time points (days 3-60).
• Quantitatively assessed VEGF expression and bone formation using computer-assisted analysis.

Main Results:

• Forward mandibular positioning significantly increased both vascularization and mandibular bone growth.
• The posterior region of the condyle showed the highest expression of both VEGF and new bone formation.
• The acceleration of vascularization consistently preceded the acceleration of new bone formation.

Conclusions:

• Forward mandibular positioning initiates a sequence of cellular events involving increased vascularization, leading to enhanced new bone formation and condylar growth.
• VEGF plays a critical role in mediating the vascular response to functional appliance therapy.
• Findings provide insights into cellular mechanisms underlying orthodontic treatment for mandibular advancement.