Three-dimensional analysis of anchorage control in alignment and leveling stage with Nance appliance

Objective To evaluate the anchorage loss in first premolar extraction cases with Nance appliance three-dimensionally during the leveling and alignment stage. Methods Forty-one orthodontic patients were selected. Enrollment criteria included moderate to severe crowding and extraction of upper first premolars. The patients were randomly divided into two groups. Twenty cases without anchorage control served as control group and 21 cases with Nance appliance served as experimental group. Lateral cephalograpms and study casts were collected before treatment and at the end of leveling and alignment stage. The dental casts were scanned with LPX-1200 three-dimensional laser scanner and analyzed using three-dimensional reverse modeling software program (Rapidform 2006(R)). Statistical analysis was performed using software package Spss 10.0. Results No significant difference was found in upper incisor inclination between control group and the experimental group. Significant difference was found in sagittal displacement, transverse movement and the rotation control of upper first molars between experimental and control groups. Conehtsions Nance appliance was effective in controlling sagittal displacement, transverse movement and rotation of the upper first molars. Key words: Nance appliance;  Model measurements;  Three-dimensional analysis; Leveling and alignment;  Anchorage loss