Bridging of mandibular defects with two different reconstruction systems: an experimental study

Area of Science:

• Oral and Maxillofacial Surgery
• Biomaterials Science
• Orthopedic Biomechanics

Background:

• Mandibular defects pose significant reconstruction challenges.
• Traditional AO plates offer limited stability, especially with bone resorption.
• Novel reconstruction systems are needed to improve fixation and long-term stability.

Purpose of the Study:

• To compare the fixation stability of the classic AO plate versus the AO-THORP reconstruction system for mandibular defects.
• To evaluate the histological and microradiographical outcomes of these reconstruction systems in a sheep model.
• To assess the biomechanical advantages of the AO-THORP system's screw-plate locking principle.

Main Methods:

• A 5-cm angular resection was performed in nine adult sheep.
• Defects were reconstructed using either a classic AO plate or the AO-THORP system.
• Histological, microradiographical, and fluorescence microscopy analyses were conducted at 5, 9, and 14 weeks post-operation.

Main Results:

• Adequate fixation was achieved in 26% of classic AO cortical screws.
• Adequate fixation was achieved in 73% of AO-THORP hollow screws.
• The AO-THORP system's locking principle maintained plate stability despite bone resorption.

Conclusions:

• The AO-THORP reconstruction system offers significantly improved screw fixation compared to the classic AO plate.
• The screw-plate locking mechanism of the AO-THORP system enhances stability in the presence of bone resorption.
• Further research is needed to determine the clinical benefit of the hollow screw design in the AO-THORP system.