Department of Orthodontics, Gangnam Severance Hospital, Institute of Craniofacial Deformity, Yonsei University College of Dentistry, Seoul, Korea.
Department of Orthodontics, University of North Carolina at Chapel Hill School of Dentistry, Chapel Hill, NC, USA.
Orthod Craniofac Res. 2021 Mar;24 Suppl 1:59-65. doi: 10.1111/ocr.12464. Epub 2021 Jan 10.
The objectives were to visualize the incisive canal (IC) remodelling following maximum incisor retraction and to evaluate its impact on canal-invasion-associated apical root resorption.
Pre- and post-treatment CBCT images of 34 adult orthodontic patients (age 18-47 years) with a large amount of maxillary incisor retraction (>4 mm) using temporary anchorage devices (TADs) were retrospectively evaluated. Maxillary regional superimpositions and 3D models of the IC along with central incisors were used to measure the changes in IC dimension, IC invasion by the roots and IC remodelling. In addition, the association of the amount of apical root resorption with the root-IC relationship and IC remodelling were evaluated.
IC invasion by the incisor roots following maximum retraction was seen in 53% (18 out of 34) of the cases. IC with larger volume and area showed more invasions compared with those with smaller volume and area (P < .01). The amount of root resorption was significantly higher with IC invasion than without invasion (2.39 mm vs 0.82 mm, P < .0001). IC remodelling following maximum retraction was seen in 24% of the subjects. IC remodelling group demonstrated less apical root resorption than the non-remodelling group (0.98 mm vs 3.27 mm, P < .0001).
IC with larger volume and surface area before treatment were more likely to show canal invasion by the incisor roots after maximum retraction. IC invasion resulted in apical root resorption. However, approximately one-fourth of cases showed remodelling of the IC, which reduced the amount of root resorption.
本研究旨在可视化最大程度内收切牙后切牙管（IC）的改建，并评估其对与管内侵犯相关的根尖根吸收的影响。
回顾性分析了 34 名成人正畸患者（年龄 18-47 岁）的 CBCT 图像，这些患者使用临时锚固装置（TADs）进行了大量上颌切牙内收（>4mm）。上颌区域叠加和 IC 以及中切牙的 3D 模型用于测量 IC 尺寸、IC 根侵犯和 IC 改建的变化。此外，还评估了根尖根吸收的量与根-IC 关系和 IC 改建的关系。
在 34 例患者中，有 53%（18 例）可见最大内收后切牙根对 IC 的侵犯。与体积和面积较小的 IC 相比，体积和面积较大的 IC 更易发生侵犯（P<.01）。与无侵犯相比，有侵犯的 IC 根吸收量显著更高（2.39mm 比 0.82mm，P<.0001）。在最大内收后，有 24%的患者出现了 IC 改建。与非改建组相比，改建组的根尖根吸收量更少（0.98mm 比 3.27mm，P<.0001）。
治疗前体积和表面积较大的 IC 更有可能在最大内收后显示切牙根对 IC 的侵犯。IC 侵犯导致根尖根吸收。然而，约四分之一的病例出现了 IC 的改建，从而减少了根吸收的量。
