| Objective: The purpose of this study is to evaluate the efficiency of mini-implant in adultpatients with bimaxillary protrusion.Methods: Based on the selective criteria, 24 patients with bimaxillary protrusion wereselected and divided into 2 groups: Experimental group(used by mini-implantanchorage)and control group(used by strong anchorage). Upper and lower first premolarson both left and right were extracted and mini-implants were inserted into buccal alveolarbone between second premolar and first molar in experimental group, meanwhilehead-gear and lingual holding arch in control group. Sliding mechanics with 50-150gforce was used to retract anterior teeth(from canine to canine). The cephalometric filmsbefore and after treatments were measured.Results:①Mini-implants remained stable during treatment except one losing and threeloosen.②The soft tissue around implant remained healthy except two cases in whichhyperplasia of soft tissue happened. All patients had good adaptability.③In experimentalgroup, dental protrusion and facial profile were improved significantly. The average oflingual movements of upper and lower incisors were 6.74 and 5.46mm in experimentalgroup respectively and 5.53 and 4.04mm in control group respectively, and there werestatistically significant differences between the two groups(p＜0.01, p＜0.001 respectively).The average of mesial movements of upper and lower first molars were 0.36 and 0.67mmin experimental group respectively, and 1.92 and 2.48mm in control group respectively,and there were statistically significant differences between the two groups(p＜0.001).④The average of reduction of Angle SNA and Angle ANB were 0.42°and 0.74°inexperimental group respectively,and 0.24°and 0.51°in control group respectively,and there were statistically significant differences between the two groups(p＜0.05, p＜0.01respectively). The average of increasing of Angle SNB was 0.32°in experimentalgroup, and 0.27°in control group, and there were no statistically significant differences between the two groups(p＞0.05).⑤The average of reduction of UL—E Plane,and LL—E Plane were 4.27 and 4.58mm in experimental group respectively and 3.90 and 4.11mmin control group respectively, and there were statistically significant differences betweenthe two groups(p＜0.01).Conclusion: Mini-implant can provide enough anchorage to retract the anterior teeth foradult bimaxillary protrusion; meanwhile, it can create clinically superior results whencompared with traditional strong anchorage systems.
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