Despite a relatively low force to deflection rate for initial archwires, the highest risk for external apical root resorption (EAAR) is during the first 6 months of treatment (initial alignment). Relative to biomechanics, the major risk factors for EARR are genetic predisposition, occlusal trauma, root flexure, PDL inflammation and cell necrosis.
Recognize the role of PDL necrosis in the biomechanics of applied loads.
Analyze the relationship between occlusal trauma and root flexure.
Compare the interactive biomechanics of PDL necrosis, occlusal trauma, and root flexure on the expression of root resorption.