Effects of accentuated and reversed curve of Spee on apical root resorption

Introduction: In this study, we evaluated the influence of intrusion mechanics with accentuated and reversed curve of Spee on root resorption of the maxillary and mandibular incisors. Methods: A sample of 60 patients with Class I and Class II Division 1 malocclusions having nonextraction treatment was divided into 2 groups with the following characteristics: group 1 comprised 30 deepbite patients, treated with accentuated and reversed curve of Spee intrusion mechanics, with an initial mean age of 12.8 ± 1.23 years (range, 10.01-15.32 years), and group 2 comprised 30 patients with normal overbite treated without intrusion mechanics, with an initial mean age of 12.87 ± 1.43 years (range, 10.02-15.36 years). Pretreatment and posttreatment periapical radiographs were used to evaluate root resorption. The groups were compared by using the Mann-Whitney U test. Correlation between root resorption and tooth movement was investigated with the Spearman correlation coefficient. Results: The deepbite group treated with accentuated and reversed curve of Spee had statistically greater root resorption (1.87) than the normal overbite group (1.54), at P = .017. Changes in overbite and vertical displacements of the maxillary central incisor apices had significant correlations to root resorption (r = 0.30, P = .019; r = 0.27, P = .037, respectively). Conclusions: Accentuating and reversing the curve of Spee in the archwires to correct deep overbite causes more root resorption than nonintrusive mechanics.