豬隻牙周膜韌帶整體生物力學行為之體外實驗

近年來齒顎矯正普及，在矯正時給予牙齒外力刺激下顎骨破壞與增生，使牙齒位置移動。牙周膜韌帶(Periodontal ligament，PDL)為介於牙齒與下顎骨之間的纖維結締組織，具有支持牙齒、組織更新、分散咀嚼時牙齒所產生的應力等功能，在生物力學研究中扮演相當重要的角色。由於牙周膜韌帶幾何形狀複雜且位於齒槽骨中，活體生理位置下製備實驗試片困難，致使牙周膜韌帶之力學特性尚未清楚完整定義。本研究使用豬牙齒試件，包括牙齒、牙周膜韌帶、下顎骨，以裝載夾置具與量測統於高解析度電腦斷層掃描(MicroCT，μCT)進行拉伸力學測試並同步記錄影像，再經由電腦斷層影像分析牙周膜韌帶拉伸前後牙齒位移情形，並另外在 MicroCT拍攝儀器外使用位移感測計(LVDT)架設於同一夾具上精準量測牙齒受拉力與位移情形之實驗，作為對照，最後重建三維有限元素牙齒與下顎骨模型，藉由實驗數據推導出牙周膜韌帶之材料力學特性。　　由目前初步實驗結果顯示牙周膜韌帶雖具有非線性性質，基於實驗限制，本研究將不討論與時間相關的黏彈性質，而將牙周膜韌帶假設為超彈性材料力學特性，進而找出超彈性模型之力學參數。本研究將生物力學測試與MicroCT結合，再利用有限元素模擬驗證，討論牙周膜韌帶受力時之生物力學反應及其力學特性。

關鍵字

牙周膜韌帶；高解析度電腦斷層掃描；位移感測計；有限元素分析

並列摘要

In recent years, the orthodontic treatment becomes more popular. Orthodontic force, which causes the absorption and deposition of the alveolar bone, would be applied through bracket and teeth in order to move the teeth to the expected position. Periodontal ligament (PDL) is composed of the fibrous connective tissue and located between the teeth and alveolar bone. The function of PDL includes teeth support, tissue regeneration and stress dissipation caused by chewing or occlusion. Due to the complex anatomy and geometry of the periodontal ligament, it is difficult to appropriately define the holistic mechanical property of PDL. 　　In this study, the porcine premolar, including tooth, periodontal ligament and alveolar bone, was harvested. A custom-made measurement apparatus was designed to install into the high-resolution computer tomography (MicroCT system, μCT) for acquiring the sectional image and reaction force at the same time. Three-dimensional model would be reconstructed by these sectional images and the displacement of the tooth could be calculated by comparison of loaded and unloaded models. Displacement sensor which was compatible to the custom-made measurement system would directly measure load-displacement relation of the PDL. Hence, the mechanical property of the PDL could be obtained. 　　The results showed that the PDL revealed the nonlinear biomechanical behavior. Due to the limitation of the experiment, the visoelastic characteristic couldn’t be accessed. This study would integrate the biomechanical experiment and finite element analysis to validate the biomechanical property of the PDL. In this study, hyperelastic model would be suitable to simulate the nonlinear behavior of the PDL and the numerical result was similar to the experimental one.

並列關鍵字

Periodontal ligament ； MicroCT ； Finite element analysis

參考文獻

1. Komatsu, K., Mechanical strength and viscoelastic response of the periodontal ligament in relation to structure. J Dent Biomech, 2010. 2010.

2. Komatsu, K. and M. Chiba, The effect of velocity of loading on the biomechanical responses of the periodontal ligament in transverse sections of the rat molar in vitro. Archives of Oral Biology, 1993. 38(5): p. 369-375.

3. Wills, D.J., D.C.A. Picton, and W.I.R. Davies, A study of the fluid systems of the periodontium in macaque monkeys. Archives of Oral Biology, 1976. 21(3): p. 175-185.

4. Pini, M., et al., Mechanical characterization of bovine periodontal ligament. J Periodontal Res, 2002. 37(4): p. 237-44.

6. Mühlemann, H.R., Periodontometry, a method for measuring tooth mobility. Oral Surgery, Oral Medicine, Oral Pathology, 1951. 4(10): p. 1220-1233.

國際替代計量

豬隻牙周膜韌帶整體生物力學行為之體外實驗

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