Malocclusion with highest risk for root resorption of the maxillary incisors

 # Which specific malocclusion, due to its inherent nature, presents the highest mechanical risk for palatal root resorption of the maxillary incisors during orthodontic alignment?

A. Skeletal Class III with severe reverse overjet

B. Deep Bite Class I with severe mandibular crowding

C. Impacting a maxillary canine horizontally near the central incisor root

D. Severe Class II Division 1

The correct answer is D. Severe Class II Division 1

In severe Class II Division 1 malocclusion, the proclined maxillary incisors necessitate substantial labial-to-lingual retraction during alignment (typically 4–7 mm bodily movement), which approximates the incisor roots to the lingual (palatal) cortical plate—reducing the root-to-cortex distance to <1 mm and imposing sustained compressive forces that elevate the risk of orthodontically induced inflammatory root resorption (OIIRR) on the palatal aspect by 1.5–2.5 times compared to Class I or III cases. Cephalometric and CBCT studies confirm this inherent biomechanical vulnerability, with resorption volumes up to 20–30% greater in retracted incisors due to limited PDL buffering against the denser palatal bone, independent of treatment duration or extractions. In contrast, skeletal Class III (A) often involves labial proclination away from the palatal plate; deep bite Class I (B) rarely requires such retraction; and canine impaction (C), while locally risky, lacks inherent malocclusal predisposition and shows no significant association when surgically distanced pre-alignment.