[Compensation of upper first molar in skeletal class Ⅲ patients treated with orthodontic-surgical treatment].

Objectives

To investigate the compensation of upper first molar in adult skeletal class Ⅲ patients.

Methods

The sample consisted of 48 skeletal class Ⅲ patients with orthodontic-surgical treatment from February 2011 to January 2015 in Peking University School and Hospital of Stomatology. They were allocated into 2 groups based on extraction, 28 patients in extraction group and 22 patients in non-extraction group. Dental casts were taken before and after treatment, and all the casts were scanned with a computer-assisted three-dimensional (3D) scanning system. Acquired 3D data were analyzed by Rapidform 2006. The tip and torque of the upper first molar were measured and analyzed.

Results

The tip and torque of the upper first molar in the skeletal class Ⅲ patients after treatment had no difference between extraction group and non-extraction group (P=0.150, P=0.144). The torque of upper first molar in extraction group [-3.32° (-5.10°, 1.16°)] before treatment was bigger than that in non-extraction group [-6.94° (-13.06°, -0.42°)] (P=0.005), and the inclination of upper first molar in extraction group was more obvious.

Conclusions

In skeletal class Ⅲ patients, the upper first molar inclined buccally to compensate the discrepancy and extraction was usually necessary for decompensation.