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Simulation of miniscrew-root distance available for molar distalization depending on the miniscrew insertion angle and vertical facial type
PLOS ONE ( IF 3.7 ) Pub Date : 2020-09-24 , DOI: 10.1371/journal.pone.0239759
Ju-Hyun Yoon , Jung-Yul Cha , Yoon Jeong Choi , Won-Se Park , Sang-Sun Han , Kee-Joon Lee

Objective

The purpose of this study was to evaluate the effects of miniscrew insertion angle and vertical facial type on the interradicular miniscrew–root distance available for molar distalization.

Materials and methods

Cone-beam computed tomography images of 60 adults with skeletal Class I occlusion exhibiting hyperdivergent (n = 20), normodivergent (n = 20), and hypodivergent (n = 20) facial types were used. Placement of a 6-mm long, 1.5-mm diameter, tapered miniscrew was simulated at a site 4 mm apical to the cementoenamel junction, with insertion angles of 0°, 30°, 45°, and 60° relative to the transverse occlusal plane. The shortest linear distance between the miniscrew and anterior root at four interradicular sites was measured: maxillary second premolar and first molar (Mx 5–6), maxillary first and second molars (Mx 6–7), mandibular second premolar and first molar (Mn 5–6), and mandibular first and second molars (Mn 6–7).

Results

Miniscrew–root distance significantly increased as the insertion angle increased from 0° to 60°. In the mandible, the distances significantly differed among vertical facial types, increasing in the following order: hyperdivergent, normodivergent, and hypodivergent. The minimum mean distance was found in the Mx 6–7 (30°; 0.86±0.35 mm), and the maximum mean distance was found in the Mn 5–6 (60°; 2.64±0.56 mm). The rates of miniscrews located buccally outside the root distalization path were up to 70% and 55% when the miniscrews were placed at 60° insertion angles in the Mx 5–6 and Mn 5–6 regions, respectively.

Conclusions

Miniscrew–root distance increased significantly with the increased insertion angle, and the amount of increase was affected by the miniscrew placement site and vertical facial type. To ensure adequate distalization of the posterior segment, the miniscrew should be inserted at an angle in the interradicular area between the second premolar and first molar.



中文翻译:

根据微螺钉插入角度和垂直面部类型,模拟可用于磨牙远侧的微螺钉牙根距离

目的

这项研究的目的是评估微螺钉插入角度和垂直面部类型对可用于磨牙远侧手术的小梁间微螺钉-牙根距离的影响。

材料和方法

使用60位成年人的I类骨骼阻塞的锥形束计算机断层扫描图像,这些面部表现出过度发散(n = 20),正发散(n = 20)和低发散(n = 20)面部类型。在水泥牙釉质结的顶端4 mm处模拟了6 mm长,直径1.5 mm的锥形微型螺钉的放置,相对于横向咬合面的插入角度为0°,30°,45°和60° 。测量了四个根尖之间的微螺钉与前牙根之间的最短线性距离:上颌第二前磨牙和第一磨牙(Mx 5–6),上颌第一和第二磨牙(Mx 6–7),下颌第二前磨牙和第一磨牙(Mn 5-6),以及下颌第一和第二磨牙(Mn 6-7)。

结果

当插入角度从0°增大到60°时,微螺钉-根部距离会明显增加。在下颌骨中,垂直面部类型之间的距离显着不同,并按以下顺序增加:超散,正散和低散。在Mx 6–7(30°; 0.86±0.35 mm)中找到最小平均距离,在Mn 5–6(60°; 2.64±0.56 mm)中找到最大平均距离。当将微型螺钉以60°插入角放置在Mx 5-6和Mn 5-6区域中时,微型螺钉在根部远侧路径之外的颊侧比率分别高达70%和55%。

结论

微型螺钉的根部距离随着插入角度的增加而显着增加,并且增加的数量受到微型螺钉放置位置和垂直面部类型的影响。为确保后段足够远侧,应将微螺钉以一定角度插入第二前磨牙与第一磨牙之间的根尖区域。

更新日期:2020-09-24
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