Oral and Maxillofacial Surgery

• Mandible lever mechanics:
  • Class III lever: Tensile forces at upper surface, compressive forces at lower border.
  • Finite element analysis: Bite force anterior/posterior to fracture → compressive forces at superior border.
• Lag screw fixation: Provides highest rigidity (2000 – 4000 N compressive force).
• Titanium plates: Least deflection under MRI; heat production is a concern.
• Stress shielding: Metallic plates cause atrophic changes due to lack of functional stimuli.
• Resorbable plates: Made of polydioxanone, polyglycolic acid, polylactic acid; degrade into CO₂ & H₂O via citric acid cycle.