Department of Orthodontics and Dentofacial Orthopedics, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, 162, Ponnamallee High Road, 600077, Chennai, Tamil Nadu, India.
J Orofac Orthop. 2024 Jan;85(1):13-29. doi: 10.1007/s00056-022-00394-7. Epub 2022 Apr 28.
The primary objective of this study was to compare the magnitude of incisor intrusion and retraction between two different treatment protocols and the secondary objective was to evaluate overall treatment effects.
Thirty-four patients with proclined upper anterior teeth, increased overbite, and incisal show were randomly assigned to two treatment groups (G1 and G2). Upper first premolar extractions were performed in all cases. In G1, space closure was performed with conventional straight-wire friction mechanics with NiTi (nickel titanium) coil springs placed on 0.019″ × 0.025″ stainless steel wires in a 0.022 slot system with an additional intrusive force via a midline mini-implant. In G2, NiTi coil springs were placed from buccal mini-implants placed onto 0.016″ × 0.022″ SS wires in a 0.022 slot system bilaterally. Lateral cephalograms and study models taken at the beginning and at the end of 6 months of treatment were assessed.
Both groups showed a statistically significant mild maxillary incisor intrusion, reduction in overjet, overbite, incisal show and a reduction in lower anterior facial height. There was a mild intrusion of the maxillary first permanent molar in G2 (not significant). Mesial movement of the maxillary first permanent molar was noted in G1 but distal movement occurred in G2. Constriction of the entire maxillary arch was noted in G1, whereas constriction was seen in the molar region only in G2. Root resorption was noticed in both groups.
Both groups produced comparable results. Except for molar control, all the results obtained were comparable between the two mechanics. Application of an intrusive force in the midline may be beneficial in patients treated with conventional straight-wire mechanics to treat increased overbite when anchorage requirement is not high.
本研究的主要目的是比较两种不同治疗方案上前牙内收和内倾的程度，次要目的是评估整体治疗效果。
34 名上颌前牙前倾、覆合增加、切牙外露的患者被随机分为两组（G1 和 G2）。所有病例均行上颌第一前磨牙拔牙。G1 组采用传统直丝弓摩擦力机械，在 0.022 槽系统中用 0.019"×0.025"不锈钢丝上的镍钛（镍钛）圈簧配合中线微型种植体施加内收力来关闭间隙。G2 组则在双侧颊侧微型种植体上放置镍钛圈簧，置于 0.016"×0.022"SS 丝的 0.022 槽系统中。在治疗的 6 个月开始和结束时拍摄侧位头颅侧位片和研究模型。
两组均显示上颌切牙有统计学意义的轻度内倾，覆合、覆盖减少，切牙外露减少，下前面部高度降低。G2 组上颌第一磨牙有轻度内倾（无统计学意义）。G1 组上颌第一磨牙发生近中移动，G2 组发生远中移动。G1 组整个上颌弓发生缩窄，而 G2 组仅磨牙区发生缩窄。两组均出现牙根吸收。
两组均取得了相似的结果。除磨牙控制外，两种力学方法的所有结果均相似。在常规直丝弓力学治疗中，当支抗要求不高时，在中线施加内收力可能对治疗覆合增加有益。
