Angle Orthod. 2022 Mar 1;92(2):189-196. doi: 10.2319/052221-408.1.
To investigate the effects of long-term use of the lower lingual arch (LLA) on the sagittal and vertical positions of the permanent lower incisors and first molars.
The sample consisted of 98 patients who were treated with an LLA (LLA group) and 39 patients who were treated without an LLA (no-LLA group). The positional changes of the lower incisors and first molars were analyzed after performing mandibular structural superimpositions on lateral cephalometric radiographs taken before treatment (T1) and at the end of LLA therapy (T2). The mean ages at T1 and T2 were 8.5 years and 13.2 years, respectively. Study casts were analyzed to quantify arch dimensional changes.
Mesial movement of the lower molar cusp was similar between the LLA and no-LLA groups, but the vertical position was slightly greater at T2 in the LLA group. In the LLA group, there was a molar tip-back effect, and the lower incisors were proclined 4.2° more than in the no-LLA group. Arch perimeter decreased 3.6 ± 2.6 mm without an LLA and 0.97 ± 3.7 mm with an LLA. Intercanine and intermolar widths both increased about 1 mm more with an LLA (P < .0001).
The LLA does not seem to restrict mesial movement and vertical eruption of the lower incisors and molars in the long term. The LLA effectively preserves the arch perimeter at the expense of a slight lower incisor proclination.
研究长期使用下颌舌弓（LLA）对恒下切牙和第一磨牙矢状和垂直位置的影响。
本研究纳入了 98 例接受 LLA 治疗的患者（LLA 组）和 39 例未接受 LLA 治疗的患者（无 LLA 组）。在治疗前（T1）和 LLA 治疗结束时（T2）的侧位头颅侧位片上进行下颌结构叠加，分析下切牙和第一磨牙的位置变化。T1 和 T2 的平均年龄分别为 8.5 岁和 13.2 岁。研究模型用于分析弓尺寸变化。
LLA 组和无 LLA 组的下颌磨牙牙尖向近中移动相似，但 LLA 组 T2 时的垂直位置略大。LLA 组存在磨牙后倾效应，下切牙前倾 4.2°，明显大于无 LLA 组。无 LLA 时，弓周长减少 3.6 ± 2.6mm，LLA 时减少 0.97 ± 3.7mm。LLA 组的尖牙间和磨牙间宽度均增加约 1mm（P<0.0001）。
长期使用 LLA 似乎不会限制下切牙和磨牙的近中移动和垂直萌出。LLA 有效地保持了弓周长，代价是下切牙略微前倾。
