OBJECTIVETo investigate the position change of upper molars and incisors in order to evaluate the stability of posterior anchorage with the application of micro-screw implant.

METHODSEight adult patients with severe maxillary protrusion were included. Upper first premolars were extracted and upper posterior anchorage was reinforced with micro-screw implant in all patients. Cephalometric and cast analyses were carried out to record the position change of molar and micro-screw.

RESULTSDuring treatment the micro-screw implants kept stable in sagittal and vertical plane. Neither the mesial-distal movement nor the tipping of the upper molars during the treatment was statistically significant (P > 0.05). The edge of upper incisors was retracted by 6.86 mm and the tipping was reduced by 18.03 degrees . The center of resistance was intruded by 3.28 mm on average. Significant change was observed (P < 0.01).

CONCLUSIONSMicro-screw implant could provide good anchorage control in the orthodontic treatment.