Department of Orthodontics, Faculty of Dental Medicine, The Hebrew University and Hadassah, Jerusalem.
Orthodontic and Craniofacial Center, Graduate School of Dentistry, Rambam Health Care Campus, Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa.
Eur J Orthod. 2021 Dec 1;43(6):665-671. doi: 10.1093/ejo/cjaa081.
Basic research in orthodontics is commonly conducted in rodents. However, experimental studies on orthodontic tooth movement (OTM) lack a standard method to examine OTM and periodontal changes. This study describes a unifying protocol for the analysis of OTM and associated bone microarchitectural changes in mice using microcomputed tomography (µCT).
Mice (10 animals/group) were divided into control and OTM groups. OTM was generated by anchoring a nickel-titanium closed-coil spring to the upper incisors to pull the upper left first molar. A third group of TNFα -/- mice was added since these are known to have slower OTM. Using µCT, we implemented and tested a number of methods to measure OTM distance and examine 3D bone morphometric parameters associated with OTM in mice.
In total, we tested five methods to measure the OTM distance in mice. The results indicated that measuring the intermolar diastema, and assessing tooth movement relative to the anterior root of the zygomatic arch, displayed the lowest standard deviation and enabled optimal detection of intergroup differences. We also developed two protocols for µCT analysis of the periradicular bone that yielded no false-positive results. Our results revealed that including the width of the periodontal ligament rather than excluding it from the region of interest in mice detected more statistically significant differences in the morphometric parameters between the OTM and control sides and between WT and TNFα -/- mice despite more subtle differences.
We, therefore, propose new guidelines for a standardized μCT-based method to analyse OTM and the extent of the periradicular bone structural changes in mice.
口腔正畸学的基础研究通常在啮齿动物中进行。然而，关于正畸牙齿移动（OTM）的实验研究缺乏一种标准方法来检查 OTM 和牙周变化。本研究描述了一种使用微计算机断层扫描（µCT）分析小鼠 OTM 及其相关骨微观结构变化的统一方案。
将小鼠（每组 10 只）分为对照组和 OTM 组。通过将镍钛闭圈弹簧固定在上切牙上来产生 OTM，以拉动左上第一磨牙。由于 TNFα-/- 小鼠的 OTM 较慢，因此添加了第三组 TNFα-/- 小鼠。使用 µCT，我们实施并测试了多种方法来测量 OTM 距离，并检查与小鼠 OTM 相关的 3D 骨形态计量参数。
总共测试了五种方法来测量小鼠的 OTM 距离。结果表明，测量磨牙间间隙，并相对于颧骨弓的前根评估牙齿移动，显示出最低的标准偏差，并能够最佳地检测组间差异。我们还开发了两种用于分析牙周骨的 µCT 方案，这些方案没有产生假阳性结果。我们的结果表明，包括牙周韧带的宽度而不是将其排除在小鼠的感兴趣区域之外，在 OTM 和对照组之间以及 WT 和 TNFα-/- 小鼠之间检测到更多在形态计量参数上具有统计学意义的差异，尽管差异更细微。
因此，我们提出了一种基于标准化 μCT 的新方法，用于分析小鼠的 OTM 和牙周骨结构变化的程度。
