Liao Zhipeng, Elekdag-Turk Selma, Turk Tamer, Grove Johnathan, Dalci Oyku, Chen Junning, Zheng Keke, Ali Darendeliler M, Swain Michael, Li Qing
School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006, Australia.
Department of Orthodontics, Faculty of Dentistry, Ondokuz Mayis University, Atakum, Samsun, Turkey.
J Biomech. 2017 Jul 26;60:57-64. doi: 10.1016/j.jbiomech.2017.06.012. Epub 2017 Jun 21.
The aim of this study is to investigate the biomechanics for orthodontic tooth movement (OTM) subjected to concurrent single-tooth vibration (50Hz) with conventional orthodontic force application, via a clinical study and computational simulation. Thirteen patients were recruited in the clinical study, which involved distal retraction of maxillary canines with 1.5N (150g) force for 12weeks. In a split mouth study, vibration and non-vibration sides were randomly assigned to each subject. Vibration of 50Hz, of approximately 0.2N (20g) of magnitude, was applied on the buccal surface of maxillary canine for the vibration group. A mode-based steady-state dynamic finite element analysis (FEA) was conducted based on an anatomically detailed model, complying with the clinical protocol. Both the amounts of space closure and canine distalization of the vibration group were significantly higher than those of the control group, as measured intra-orally or on models (p<0.05). Therefore it is indicated that a 50Hz and 20g single-tooth vibration can accelerate maxillary canine retraction. The volume-average hydrostatic stress (VHS) in the periodontal ligament (PDL) was computationally calculated to be higher with vibration compared with the control group for maxillary teeth and for both linguo-buccal and mesial-distal directions. An increase in vibratory frequency further amplified the PDL response before reaching a local natural frequency. An amplification of PDL response was also shown to be induced by vibration based on computational simulation. The vibration-enhanced OTM can be described by mild, vigorous and diminishing zones among which the mild zone is considered to be clinically beneficial.
本研究旨在通过临床研究和计算机模拟，研究在传统正畸力施加的同时进行单颗牙齿振动（50Hz）时正畸牙齿移动（OTM）的生物力学。临床研究招募了13名患者，该研究涉及使用1.5N（150g）的力使上颌尖牙远中移动12周。在一项双侧对照研究中，为每个受试者随机分配振动侧和非振动侧。对于振动组，在上颌尖牙的颊面施加频率为50Hz、幅值约为0.2N（20g）的振动。基于符合临床方案的详细解剖模型进行了基于模态的稳态动态有限元分析（FEA）。通过口腔内测量或模型测量，振动组的间隙关闭量和尖牙远中移动量均显著高于对照组（p<0.05）。因此表明，50Hz和20g的单颗牙齿振动可加速上颌尖牙的远中移动。计算得出，与对照组相比，上颌牙齿在牙周膜（PDL）中的体积平均静水应力（VHS）在舌颊向和近远中向均因振动而更高。在达到局部固有频率之前，振动频率的增加进一步放大了牙周膜的反应。基于计算机模拟也显示振动可诱导牙周膜反应的放大。振动增强的OTM可分为轻度、剧烈和减弱区，其中轻度区被认为在临床上是有益的。
