Comparative study of the rate of tooth movement between corticotomy and piezocision to facilitate en masse retraction in bimaxillary protrusion

Abstract

Objective: The aim of this study was to evaluate the rate of orthodontic tooth movement and the time needed for extraction space closure when corticotomy and piezocision were used to facilitate en-masse retraction in bimaxillary protrusion cases. Subjects and Methods: The sample of this study consisted of twenty subjects having Class I malocclusion with bimaxillary protrusion and requiring extraction of four first premolars and en-masse retraction of the anterior segments on both arches. The sample was randomly divided into two equal groups; group I:corticotomy was performed by using piezosurgery through flap reflection and group II: corticotomy was performed by using piezocision (flapless corticotomy). Study models were obtained just before surgery and in every month for 6 months after surgery to measure the rate of orthodontic tooth movement in both groups. After completing the en-masse retraction, the retraction time in months was recorded for the right and left sides and averaged. Results: Group I showed a statistically significant shorter retraction time than group II. Group I showed a statistically significant increase in the rate of tooth movement from the 2nd to the 5th month in the upper arch. For the lower arch, group I exhibited a significant increase in the rate of tooth movement in the 4th month. Conclusion: Corticotomy involving flap reflection showed a shorter retraction time and higher rates of tooth movement than piezocision during en-masse retraction.