Three-dimensional zone of the centers of resistance of the mandibular incisors and canines: A novel approach by finite element analysis

IF 1.8 Q2 DENTISTRY, ORAL SURGERY & MEDICINE

International Orthodontics Pub Date : 2024-10-29 DOI:10.1016/j.ortho.2024.100933

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引用次数: 0

Abstract

Objectives

The distribution and size of the zone of the centres of resistance (ZCR) are critical for accurate orthodontic treatments and minimizing unexpected tooth movements. However, this information remains unclear for mandibular incisors and canines. This study aims to address these gaps in knowledge.

Methods

Finite element models of four incisors and canines from four individuals were created. Four centres of resistance (CRs) under four orthodontic directions (0° ∼ 45° ∼ 90° ∼ 135° to the sagittal plane in the horizontal plane) were assessed by a novel method. The height of the CRs was normalized to a percentage of the long axis, and the offsets were expressed as a distance value after normalization. The ZCR was obtained by fitting a 90% confidence sphere of the CR distribution. Validation was conducted to find the perturbations when the positions out of the zone were applied.

Results

The maximum variation of CR in the heights under four directions was 5.17% and 3.70% for the incisors and canines, respectively. The maximum offset between the CR and long axis was 0.14 mm in incisors and 0.99 mm in canines. The height of the zone in the incisor and canine was 57.75% and 59.72%, and the radius of the zone was 0.60 mm and 0.65 mm, respectively. The force-acting point outside the zone produced a large rotation, which was unexpected.

Conclusions

The ZCR of mandibular incisors located slightly lower than that of canines, but they were almost the same size. The ZCR was recommended as the “gold reference” for orthodontics to reduce unexpected movement.

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下颌切牙和犬齿阻力中心的三维区域：有限元分析的新方法

目的阻力中心区（ZCR）的分布和大小对于准确的正畸治疗和减少牙齿意外移动至关重要。然而，下颌切牙和犬齿的这一信息仍不清楚。本研究旨在填补这些知识空白。方法创建了四个人的四颗门牙和犬齿的有限元模型。采用一种新方法评估了四个正畸方向（水平面与矢状面成 0° ∼ 45° ∼ 90° ∼ 135°）下的四个阻力中心（CRs）。CR 的高度归一化为长轴的百分比，偏移量以归一化后的距离值表示。ZCR 是通过拟合 CR 分布的 90% 置信球来获得的。结果切牙和犬齿在四个方向下高度的 CR 最大变化率分别为 5.17% 和 3.70%。门牙 CR 与长轴之间的最大偏差为 0.14 毫米，犬齿为 0.99 毫米。门牙和犬齿的区域高度分别为 57.75% 和 59.72%，区域半径分别为 0.60 毫米和 0.65 毫米。结论下颌切牙的ZCR略低于犬齿，但两者的大小几乎相同。建议将 ZCR 作为正畸的 "黄金参考值"，以减少意外移动。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

International Orthodontics DENTISTRY, ORAL SURGERY & MEDICINE-

CiteScore

2.50

自引率

13.30%

发文量

审稿时长

26 days

期刊介绍： Une revue de référence dans le domaine de orthodontie et des disciplines frontières Your reference in dentofacial orthopedics International Orthodontics adresse aux orthodontistes, aux dentistes, aux stomatologistes, aux chirurgiens maxillo-faciaux et aux plasticiens de la face, ainsi quà leurs assistant(e)s. International Orthodontics is addressed to orthodontists, dentists, stomatologists, maxillofacial surgeons and facial plastic surgeons, as well as their assistants.