微螺钉种植支抗稳定性的临床研究

Clinical study of stability of miniscrew implant used as Onthodontic Anchorage

目的:研究微螺钉加载正畸负荷后的稳定性。方法:本研究包括了15例成年患者,以植入上颌颧突的微螺钉作为前牙内收的颌内支抗。微螺钉植入2周后施力。加力前及加力后9个月分别拍摄X线头颅定位片,将头影测量片进行重叠,测量微螺钉的移位变化。结果:15例中6例患者的微螺钉伸出并移位(-0.5～1.5mm)。微螺钉头部平均向前移位0.4mm,有统计学意义(P<0.05)。结论:微螺钉是一种稳定的支抗装置,但是在承载正畸负荷的过程中,并不保持绝对的稳定,部分微螺钉在正畸力作用下有移位。为了防止因微螺钉移位伤及临近的重要组织结构,建议微螺钉应植入在没有主要神经、血管通过的非齿槽骨区,或植入在齿槽间隔区,但微螺钉与牙根之间应留出2mm的安全距离。

Objective To study the stability of miniscrew anchorage under orthodontic force. Methods Fifteen adult patients with miniscrews as the maxillary anchorage were included in this study.Miniscrews were inserted on the maxillary zygomatic buttress as a direct anchorage for anterior teeth etraction.Nicket-titaniun closed-coil springs were placed for the retraction 2 weeks after insertion of the miniscrews.Cephalometric radiographs were taken immediately before force application and 9 months later.The cephalometric tracings were superimposed to determine any movement of the miniscrews. Results The miniscrews were extruded and tipped forward （-0.5 to 1.5mm）in 6 of the 15 patients.On average,the miniscrews tipped forward significantly,by 0.4mm at the screws head. Conclusion Miniscrews are a stable anchorage but do not remain absolutely stationary throughout orthodontic loading.They might move according to the orthodontic loading in some patients.To prevent miniscrews hitting any vital organs because of displacement,it is recommended that they be placed in a non-tooth-bearing area that has no foramen,major nerves,or blood vessel pathways,or in a tooth-bearing area allowing 2mm of safety clearance between the miniscrew and dental root.