Jiang Feifei, Kula Katherine, Chen Jie
a PhD Candidate, Department of Mechanical Engineering, Indiana University Purdue University Indianapolis (IUPUI), Indianapolis, Ind.
b Professor and Chair, Department of Oral Facial Development, Indiana University, Indianapolis, Ind.
Angle Orthod. 2016 May;86(3):365-71. doi: 10.2319/051215-322.1. Epub 2015 Sep 24.
To develop a method to quickly estimate the location of center of resistance (CR) in mesial-distal (MD) and buccal-lingual (BL) directions from the tooth's image.
The maxillary cone-beam computed tomography (CBCT) scans of 18 patients were used. Finite element (FE) models of the canines and their surrounding tissues were built based on their CBCT scans to calculate the locations of CR. Root length, centroid of the contact surface (CCS), and centroid of projection of the contact surface (CPCS) were also obtained from the images. The CCS and CPCS locations were projected on the tooth's long axis, which were represented as percentages of the root length measured from the root's apex.
Using the FE results as the standards, the errors of using CCS or CPCS to estimate CR were calculated. The average location of CR calculated using the FE method was 60.2% measured from the root's apex in the MD direction and 58.4% in the BL direction. The location of the CCS was 60.9%. The difference in CR was 0.7% in the MD direction and 2.5% in the BL direction. The location of CPCS was 60.2% in the MD direction and 59.1% in the BL direction, which resulted in a 0.1% and 0.8% difference with the reference CR, respectively. The average difference of CR in the MD and BL directions was small but statistically significant (P < .05).
The locations of the CR of a human canine in the MD and BL directions can be estimated by finding the CPCSs in those directions.
开发一种从牙齿图像快速估计近远中（MD）和颊舌（BL）方向阻力中心（CR）位置的方法。
使用18例患者的上颌锥形束计算机断层扫描（CBCT）图像。基于CBCT扫描构建犬齿及其周围组织的有限元（FE）模型，以计算CR的位置。还从图像中获取根长、接触面质心（CCS）和接触面投影质心（CPCS）。将CCS和CPCS的位置投影到牙齿长轴上，以从根尖测量的根长百分比表示。
以FE结果为标准，计算使用CCS或CPCS估计CR的误差。使用FE方法计算的CR平均位置在MD方向上从根尖测量为60.2%，在BL方向上为58.4%。CCS的位置为60.9%。CR在MD方向上的差异为0.7%，在BL方向上为2.5%。CPCS在MD方向上的位置为60.2%，在BL方向上为59.1%，与参考CR的差异分别为0.1%和0.8%。CR在MD和BL方向上的平均差异较小，但具有统计学意义（P <.05）。
通过找到人犬齿在MD和BL方向上的CPCSs，可以估计其CR位置。
