Yona Shai, Medina Oded, Shvalb Nir, Sarig Rachel
The Department of Mechanical Engineering, Faculty of Engineering, Ariel University, Israel.
The Goldschleger School of Dental Medicine, Faculty of Medical and Health Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel.
Heliyon. 2024 Jul 5;10(14):e34175. doi: 10.1016/j.heliyon.2024.e34175. eCollection 2024 Jul 30.
The current study aims to explore the stress distribution along the roots of palatally positioned maxillary canines during orthodontic movement using a novel computational spring model.
An experimental analysis based on the spring-model was utilized to calculate Orthodontic Tooth Movement (OTM) and the resulting stresses. Two sets of experiments were conducted: the first set compared stresses on a canine resulting from a single force and a force-couple, while the second set simulated canines' traction during instantaneous movement with varying original tooth angulations using different off-the-shelf orthodontic coils. In total, 130 simulations were performed.
The model provided estimated stress distribution throughout the OTM with the expected movements, producing consistent outcomes with prior findings. In the first set of experiments, the force couple exhibited an average stress of 43 KPa, while a single force yielded 51 KPa on average. The maximum stress observed was 63 KPa for the force couple and 130 KPa for a single force. Note that the stress distribution attributed to the force couple was alleviated in comparison to the stress distribution caused by a single force. Force couples generated higher average stress. In the second experiment, the application of an occlusally-directed inclined force led to reduced stress levels overall. For instance, when a 200 g distal force was exerted on the canine, it generated an average stress of 20 KPa, whereas applying a force of the same magnitude in an occlusal-distal direction resulted in a lower average stress of 15.5 KPa.
Lower average stress levels when using a force couple indicate that larger loads might be safely applied for rotational movements. Given that areas under maximal stress are prone to damage, orthodontic treatment planning should carefully consider stress distribution to minimize potential harm in these high-stress zones. The results also suggest that force couples enable the use of stronger forces than a single force. Additionally, it is advisable to extrude the tooth initially before starting any horizontal movement towards the target position.
Given that orthodontic treatment often relies on virtual planning, incorporating a variety of methods to evaluate stress distribution within the treatment strategy could offer numerous benefits. Such an approach holds the potential to improve both the efficiency and safety of orthodontic treatments, especially in complex cases that require the application of high forces.
本研究旨在使用一种新型计算弹簧模型，探索正畸移动过程中腭侧上颌尖牙牙根周围的应力分布情况。
采用基于弹簧模型的实验分析方法来计算正畸牙齿移动（OTM）及由此产生的应力。进行了两组实验：第一组比较了单力和力偶作用于尖牙时产生的应力，第二组使用不同的现成正畸线圈模拟了不同初始牙角度下尖牙瞬时移动过程中的牵引情况。总共进行了130次模拟。
该模型在整个正畸牙齿移动过程中提供了估计的应力分布及预期的移动情况，产生的结果与先前研究一致。在第一组实验中，力偶的平均应力为43千帕，而单力平均产生51千帕的应力。观察到的最大应力，力偶为63千帕，单力为130千帕。需要注意的是，与单力引起的应力分布相比，力偶引起的应力分布有所减轻。力偶产生的平均应力更高。在第二个实验中，施加向咬合方向的倾斜力总体上导致应力水平降低。例如，当对尖牙施加200克的远中力时，产生的平均应力为20千帕，而在咬合远中方向施加相同大小的力时，平均应力较低，为15.5千帕。
使用力偶时平均应力水平较低，这表明对于旋转移动可以安全地施加更大的负荷。鉴于最大应力区域容易受损，正畸治疗计划应仔细考虑应力分布，以尽量减少这些高应力区域的潜在危害。结果还表明，力偶能够使用比单力更强的力。此外，在开始向目标位置进行任何水平移动之前，建议先对牙齿进行伸长。
鉴于正畸治疗通常依赖于虚拟计划，在治疗策略中纳入多种评估应力分布的方法可能会带来诸多益处。这种方法有可能提高正畸治疗的效率和安全性，特别是在需要施加高力的复杂病例中。
