American Board of Orthodontics (ABO) Practice Exam

Maxillary incisors are the teeth most commonly affected by external resorption due to several factors inherent to orthodontic treatment and their anatomical features. During orthodontic treatment, the application of forces on teeth can lead to changes in the periodontal ligament and surrounding bone, possibly resulting in resorption of the tooth root.

Maxillary incisors are particularly susceptible for a few reasons. Their relatively thin roots, combined with the proximity of the roots to the labial and lingual plates of bone, may facilitate resorption. Additionally, these teeth are often subject to significant forces during orthodontic treatment, especially in cases where space closure or retraction is involved.

Moreover, maxillary incisors are also commonly involved in trauma cases where external resorption may occur as a response to injury, which could further increase their predisposition to this condition. Understanding the factors that lead to resorption, especially in maxillary incisors, is crucial for orthodontic practitioners to prevent and manage potential complications during treatment.