Skeletal and dental changes after lower posterior tooth extrusion in Class II Division 1 deep bite short-faced growing patients

Abstract

Objectives: The objectives of the study were to investigate the effect of lower posterior tooth extrusion on skeletal and dental changes in Class II division 1 deep bite short-faced growing patients. Materials and Methods: Twenty-two growing patients with Class II/1 malocclusion deep bite/short-face were treated using a pre-adjusted edgewise-fixed appliance. The curve of Spee (COS) was leveled by rectangular wire and posterior vertical elastic. Two consecutive lateral cephalometric radiographs were collected before and after treatment. Changes from the cephalometric analysis were compared with 22 untreated matched subjects during the observation period with independent t-test. Results: The reduction of deep bite from the COS in the treated group was 2.83 mm which was obtained by a greater amount of posterior extrusion (1.37 mm), than anterior intrusion (0.58 mm), and lower facial height significantly increased (3.70 mm). The treated group showed significant forward mandibular position from SNB (1.36°), Pg-Nperp (1.53 mm), and the skeletal relationship improved (ANB = −0.88°). The mandibular plane angles (SN-MP and FMA) showed no significant changes during treatment. Dental changes revealed significant decreases in overjet and overbite, whereas the position and inclination of the upper and lower incisors were not significantly different. Conclusions: The increase of lower facial height in Class II deep bite short-faced growing patients was successfully accomplished by lower posterior tooth extrusion with the use of rectangular wire with posterior vertical elastic. The mandibular plane angle did not change during treatment. Class II skeletal relationship improved by the forward position of the mandible in hypo-and normodivergent pattern subjects.