Advisory Committee Chair
Advisory Committee Members
Chung H Kau
Date of Award
Degree Name by School
Master of Dentistry (MDent) School of Dentistry
External Apical Root Resorption (EARR) is a side effect of orthodontic treatment that results in root shortening in about one-third of orthodontic patients. Great variability among patients exists in their susceptibility to this multifactorial condition, and both treatment and patient specific factors contribute to EARR. Root resorption values were found to be higher in Hispanics compared to Asians and Caucasians (1). However, the prevalence of EARR is not well documented in all populations. Since African Americans represent the largest minority group in the United States, establishing the prevalence and risk factors for EARR within this ethnicity is important. Objective: To determine the prevalence of EARR in African Americans and to evaluate the effects of patient and treatment related factors. Methods: The records of 336 African Americans treated orthodontically at the University of Alabama at Birmingham Department of Orthodontics were retrospectively analyzed. We excluded patients with histories of craniofacial syndromes, dental trauma, or prior orthodontic treatment. Additionally, patients with evidence of open apexes and lack of visible radiographic landmarks were excluded. Crown-to-root ratios were measured by a technique developed by Lind (2) and modified by Holtta et al. (3). Dolphin Imaging software (Chatsworth, CA) was used to digitize pre-treatment and post-treatment panoramic radiographs for each patient. Moderate and severe EARR was recorded when 20% and 50% or more of the root structure was lost for any of the four incisors, respectively. Additionally, we recorded averall root resorption of equal or greater than to 2 mm. The Pearson chi-square test was used to calculate the effects of individual patient (age, gender, skeletal and dental classification, incisor proclination and overjet) and treatment-related (type and time) factors on EARR. Results: The prevalence of moderate and severe EARR was 29.8% and 0.3%, respectively. The prevalence of root resorption when 2 mm or greater amount of the root structure is lost was 51.8%. The prevelance of EARR for upper central incisors was 10.5%. The prevalence of EARR for upper lateral incisors was 10%. The associations between the patient specific and treatment specific variables and moderate EARR were not statistically significant. Conclusions: About a third of the African American patients will exhibit EARR with orthodontic treatment. While EARR is a multifactorial condition, in this minority there are no significant associations with treatment related factors. Furthermore, patient related factors such as age, gender, dental malocclusion and skeletal classifications do not indicate a significant correlation with the risk of developing EARR. This suggests that other factors such as genetic influences may be more significant in predisposing patients to EARR.
Litchfield, Frank Earl, "External Root Resorption In The Orthodontic Patients" (2019). All ETDs from UAB. 2304.