Development of a mechanical testing system for a mandibular distraction wound

Area of Science:

• Biomechanical Engineering
• Regenerative Medicine
• Oral and Maxillofacial Surgery

Background:

• Distraction osteogenesis (DO) is crucial for mandibular reconstruction.
• Accurate assessment of bone healing and stiffness is vital for successful DO outcomes.
• Existing methods may alter the morphology of the healing mandible, complicating evaluation.

Purpose of the Study:

• To develop and validate a mechanical testing system for estimating the stiffness of experimental porcine mandibular distraction osteogenesis (DO) wounds.
• To ensure the testing system functions without causing morphological changes to the healing mandible.
• To assess the stiffness of mandibular bone regenerate at various stages of healing.

Main Methods:

• A customized jig was designed for cantilever-bending tests on Yucatan mini-pig hemi-mandibles.
• A material testing unit applied controlled force to the hemi-mandible, measuring displacement.
• Stiffness was calculated as the slope of the force-displacement curve.
• Radiographs were used to detect any morphologic changes or fractures post-testing.

Main Results:

• Control hemi-mandibles exhibited a stiffness range of 0.018–0.317 kN/mm (mean 0.099 kN/mm).
• Experimental DO hemi-mandibles showed significantly lower stiffness, ranging from 0–0.025 kN/mm (mean 0.005 kN/mm).
• Radiographic analysis confirmed no gross morphologic changes or fractures after mechanical testing.

Conclusions:

• The developed cantilever-bending model is effective for assessing the stiffness of mandibular DO wounds.
• This non-destructive method allows for reliable biomechanical evaluation of bone regeneration.
• The system provides valuable data for understanding mandibular healing dynamics after DO.