How effective is a thick plate on stabilisation in 10 mm mandibular advancement?

Area of Science:

• Oral and Maxillofacial Surgery
• Biomechanical Engineering
• Orthodontic Research

Background:

• Sagittal split ramus osteotomy (SSRO) is a common procedure in orthognathic surgery.
• Stability of fixation is crucial for successful SSRO outcomes.
• Various fixation methods exist, each with potential advantages and disadvantages.

Purpose of the Study:

• To compare the biomechanical stability and stress distribution of four distinct fixation techniques following SSRO in mandibular models.
• To evaluate the efficacy of different plate and screw configurations under simulated occlusal loading.

Main Methods:

• Four fixation methods were tested on mandibular models: single plate/single screw (1P1B), double plate (2P), three bicortical screws (3B), and reinforced plate/single screw (1RP1B).
• A static vertical load of 200 N was applied to the first molar region of each model.
• Finite element analysis was used to measure von Mises stress and displacement at the osteotomy site.

Main Results:

• The three bicortical screws (3B) group exhibited the lowest maximum von Mises stress (1121.4 MPa) and displacement (0.79 mm), indicating superior stability.
• The single plate/single screw (1P1B) group showed the highest stress (2705.21 MPa) and displacement (1.92 mm).
• The double plate (2P) and reinforced plate (1RP1B) groups showed intermediate results, with the reinforced plate not being as effective as the 3B or 2P methods.

Conclusions:

• Fixation with three inverted L-shaped bicortical screws provides the greatest biomechanical stability for SSRO compared to the tested plate configurations.
• Double plating also offers significant stability, superior to single plating or a single reinforced plate.
• These findings suggest that fixation choice significantly impacts SSRO stability, with bicortical screw constructs being highly effective.