微种植钉压低下颌切牙的临床效果观察

Applicatioin of micro-screw for mandibular incisors intrusion： a clinical and cephalometric study

目的观察在正畸过程中，微种植钉对于压低下颌切牙、整平Spee曲线的临床效果。方法选取15例深覆颌病例，男5例，女10例，年龄11．3～28．8岁。平均17．2岁，均为安氏Ⅱ类1分类错精。采用拔牙矫治方式．并分别在下颌牙弓纳入平整的0．457mm×0．635ram（0．018英寸×0．025英寸）镍钛方丝时，于下颌两侧侧切牙与尖牙的牙根间置人微种植钉。微种植钉加力前及下颌切牙已充分压入时拍摄X线头颅侧位片．通过头影测量分析评价微种植钉压低下前牙的治疗效果。结果得出下颌切牙平均压入（4．10±0．98）mm；下颌磨牙平均伸长（0．91±0．69）mm；下颌切牙压入的量与磨牙伸长的量之比是4．5：1．0；下颌切牙长轴与下颌平面的交角（IMPA）变化平均值是（-0。09±4．12）°；下颌平面角（FMA）变化平均值是（0．25±0．70）°。结论临床上使用微种植钉配合镍钛丝整平Spee曲线时。不但能有效地加速下颌切牙的压人，同时也有效减少下颌磨牙过多伸长。

Objective To evaluate the effects of micro-screw on the intrusion of lower incisors and the leveling of curve of Spee in the process of orthotherapy. Methods Fifteen patients （5 males, 10 females） with deep-bite were selected, aged from 11.3 to 28.8 years, with average of 17.2 years. All of them were Angle Class Ⅱ Classification 1 malocclusion and had a curve of Spee larger than 3 ram. Orthotherapy of extraction was adopted for the first premolars of two upper mandible and see- ond premolars of two lower mandihle. All these patients had micro-screws implanted at root apex area between lower lateral incisor and canine bilaterally, and when the 0. d57 min×0. 635 mm （0. 018 in ×4 0. 025 in） Ni-Tisquare wire was internalized, the strength of intrusion from micro-screws was used. Lateral cephalometric radiographs were taken before loading the micro-screw and immediately when the curve of Spee was leveled. Two linear and two angular measurements were selected for cephalo- metric analysis. Results The following results were noted： the lower incisors were significantly intru- ded for a mean of （4. 10±0. 98） ram; the mandibular molars were not significantly extruded for a mean of （0.91±0.69） ram; some lower incisors proclined and some lower incisors retroclined for a mean of （-0.09±4. 12）°. After bite opening, the mandibular plane angle was minimally altered fora mean of （0. 25±0. 70）°; the ratio of lower incisor intrusioin to lower molar extrusion was 4.5 ： 1.0. Conclusions The combined use of micro-screw with Ni-Ti wire is capable of enhancing the intrusion of lower incisors and leveling the curve of Spee, and it has minimal side effects on the posterior teeth.