Predictor of increased idiopathic external apical root resorption (EARR) during fixed orthodontic treatment

 # Which pre-treatment occlusal factor is considered a significant, independent predictor of increased idiopathic external apical root resorption (EARR) during fixed orthodontic treatment?

A. Deep, traumatic overbite with incisor contact

B. Mild Class III Malocclusion with reverse overjet

C. Severe Mandibular Anterior Crowding

D. Pre Treatment history of TMD pain

The correct answer is A. Deep, traumatic overbite with incisor contact

Deep, traumatic overbite—where mandibular incisors impinge on maxillary incisor edges or palatal gingiva—necessitates corrective mechanics like incisor intrusion or torque adjustments during fixed orthodontic treatment, which exert sustained compressive forces on the periodontal ligament and cementum, elevating idiopathic EARR risk by 1.5–2.5 times compared to non-traumatic deep bites (p < 0.05). Multivariate analyses confirm this as an independent pre-treatment predictor, distinct from treatment duration or extractions, due to the heightened biomechanical stress on apical regions during bite opening. In contrast, mild Class III (B) often involves proclined lowers with less intrusive needs; severe mandibular crowding (C) correlates modestly via root-cortical proximity but not independently for incisor EARR; and TMD history (D) shows no significant association in prospective cohorts.