Evaluation of root resorption after open bite treatment with and without extractions.

INTRODUCTION: In this study, we evaluated the root resorption degree in open bite and normal overbite patients, treated with and without premolar extractions.

METHODS: A sample of 120 patients was selected and divided into 4 groups. Group 1 comprised 32 patients treated with premolar extractions with an initial mean age of 14.01 +/- 2.58 years and an initial mean overbite of -3.45 +/- 0.23 mm. Group 2 included 28 open bite patients treated without extractions, with an initial mean age of 13.27 +/- 2.75 years and an initial mean overbite of -3.10 +/- 0.24 mm. Group 3 comprised 30 patients with normal overbite, treated with premolar extractions, having a mean age of 13.28 +/- 1.79 years and a mean overbite of 1.09 +/- 0.24 mm at the beginning of treatment. Group 4 consisted of 30 patients with normal overbite, treated without extractions, at a mean age of 12.87 +/- 1.43 years and a mean overbite of 1.67 +/- 0.24 mm at the beginning of treatment. The groups were matched by initial age, treatment time, and malocclusion type. Pretreatment and posttreatment periapical radiographs were used to evaluate the amount of root resorption. The groups were compared by using the Kruskal-Wallis and Dunn nonparametric tests. Correlations between the degree of root resorption and amount of tooth movement, usage time of anterior vertical elastics, and treatment time were investigated with the Spearman correlation coefficient.

RESULTS: No statistically significant difference was found between the root resorption degrees of open bite vs normal overbite groups, but the extraction groups had statistically significant greater root resorption than the nonextraction groups. Significant correlations were observed in the extraction groups between root resorption degree and amount of overjet correction and retraction of maxillary incisor apex.

CONCLUSIONS: Root resorption was similar between open bite and normal overbite treatment protocols, but extraction treatment showed greater root resorption than nonextraction treatment. There was a statistically significant correlation of overjet correction and retraction of maxillary central incisor apices with the degree of root resorption.