Links Between Tooth Root Shape, Root Length, and Orthodontically Induced Root Apical Resorption

Abstract

Background: The risk factors associated with external apical root resorption can be broadly categorized into patient-related and orthodontic treatment- related factors. Patient-related factors contributing to external apical root resorption include genetic predisposition, systemic conditions, asthma, allergies, chronic alcoholism, the severity of malocclusion, the group of teeth affected by resorption, root shape, alveolar bone density, the proximity of the root to cortical bone, prior endodontic treatment, as well as the patient's age and gender. Orthodontic treatment-related factors encompass the duration of treatment, the magnitude and direction of the applied forces, the degree of apical displacement, and the method of force application. Numerous studies have investigated the potential association between the occurrence of root resorption during orthodontic treatment and abnormal dental morphologies, including agenesis, pipette-shaped, blunt, pointed, short, long, dilacerated, and narrow roots, as well as small and peg-shaped lateral incisors, dental invagination, and taurodontism. Objectives: This study aimed to determine the potential relationship between orthodontic root resorption, abnormal dental root morphology, and root length. It was decided to detect normal, blunt, bent, pointed, pipette-shaped, and short roots from all resorbed teeth from 40 computed tomography (CT) images. Methods: To fulfill the study's objective, patients from the research and control groups underwent cone-beam computed tomography (CBCT) examinations. Results: A detailed analysis of the study groups reveals a significant correlation between root apical morphology in shortened, pointed, and bent root forms. High reliability was found concerning gender, with EAAR being identified predominantly in females. Conclusions: The teeth most susceptible to external apical root resorption are those with shortened roots. Additionally, apical pointed and bent morphology exhibits a higher resorption risk than petite-shaped and long roots. In contrast, blunt roots demonstrate a high resistance to EAAR.