Objective To evaluate the treatment results of patients with maxillary protrusion by using self-drilled microscrew implant as strong anchorage． Methods The study comprised 50 patients with maxillary protrusion. All patients were treated with maxillary first premolar extraction by using self-drilled microscrew implant anchorage. Self-drilled microscrew implants were inserted into the bilateral buccal alveolar bone between maxillary second premolar and first molar. 0.98 N force each side was added to the microscrews and retracted anterior teeth until the extraction spaces were closed entirely. The cephalometric films before and after treatment were measured and compared. Results 1）All microscrew implants remained steady throughout the orthodontic treatment． 2）The extraction spaces were closed entirely and the dentition arch protrusions improved greatly． The edges of maxillary incisors were retracted by 7.57 mm at average． The angle between the axis of incisor and SN decreased 13.40° at average． The angle between the axis of incisor and NA decreased 12.82° at average． The back angle between the axis of upper incisor and lower incisor increased 20.56° at average． The anterior overjet decreased 7.94 mm at average． The linear distance between the conflict point of upper lip and aesthetic plane decreased 5.52 mm at average． The differences of upper incisors before and after treatment were statistically significant． Upper first molars moved mesially by 0.01 mm and vertically by 0.09 mm at average． There were no significant changes in anteroposterior and vertical directions for upper first molars． 3）All patients’facial profile were improved greatly. They all set up correct overbite and overjet and good molar relationship. Conclusion Self -drilled microscrew implants were stable，comfortable and efficient and could provide good anchorage control in the maxillary protrusion treatment with no loss of molar anchorage. The maxillary anterior teeth were retracted together effectively by using self-drilled microscrews as strong anchorage and the maxillary protrusions were corrected effectively.
