- 學位論文
人類單根牙牙周韌帶生物力學行為模式之研究
Investigation of Biomechanical Behavior of Periodontal Ligament of Human Single Rooted Tooth
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摘要
人類牙周韌帶不僅扮演著支持自然牙齒穩定位於齒槽骨的重要角色，也能做為緩衝過強力量以減緩牙齒受到外傷的重要生物構造。現今人工植牙於缺牙區域重建已為相當普遍之治療方式；然而，由於人工牙根缺乏做為緩衝能力的構造，而衍生了諸多植牙長期使用之後的問題。例如：補綴物斷裂，植體斷裂、周圍齒槽骨喪失、螺絲鬆脫、咬合創傷…等。因此探究生物體牙周韌帶的生物力學模式，研發新式具備緩衝能力設計的人工牙根以達增進廣大缺牙病患生活品質的目標刻不容緩。由於過往的研究多著重於有關牙周韌帶離體實驗，活體測量的文獻及研究成果較為缺乏。因此，本研究的目的在於探究人類活體中牙周韌帶的生物力學模式。 本研究係以精密測量裝置，利用安全且非侵入性的方式測量，取得人類單根牙之牙周韌帶受力時的資料。受試者來源取自台大醫院口腔顎面外科門診病患，採隨機抽樣方式，收集十位符合資格之臨床受試者(四位男性，六位女性)。口內量測儀器透過控制不同施力大小、速率及施力時間長短來模擬不同受力狀態，並精準地量測牙齒位移。研究目標為探討牙周韌帶的彈性係數以及其受力時的生物力學模式，透過進行應力-位移、潛變、應力鬆弛以及遲滯等測試來驗證人類牙周韌帶是否具有黏彈性材料的性質。 研究結果顯示人類單根牙牙周韌帶經施力後具有潛變，應力鬆弛，以及遲滯現象等黏彈性材料之特性，可以使用Maxwell-Voigt elements模型來說明其力學模型。本實驗將下顎區門牙依照壓入量分為25 μm、50 μm及75 μm三個組別，其平均消散能量分別為1.61±0.71、3.98±2.14及11.29±4.12 (單位：1×10-2 mJ)且呈現指數關係往上增加的趨勢。人類自然牙牙周韌帶楊氏模數範圍介於0.068 MPa至0.491 MPa，平均為0.231 MPa，標準差為0.137 MPa。 受試牙的Periotest M value與壓入位移25 μm組別的消散能量以卡方檢定檢測。結果得分為0.667(大於0.05)。故Periotest M value與25 μm遲滯線圈的消散能量沒有統計上的顯著差異。自然牙在垂直位移25 μm、50 μm及75 μm組別平均形變量分別為8.60±3.90 μm、19.12±11.17 μm及24.06±14.97 μm，顯示隨著壓入位移增加牙周韌帶平均形變量以二次函數關係增加；但其平均形變率(deformation rate)分別為44.56±18.74%、47.06±26.96%及43.30±20.65%，範圍落在43.3%到44.56%之間，不受壓入位移增減所影響。 綜合以上實驗結果指出人類牙周韌帶具有黏彈性材料的性質。本實驗建立了標準化量測人類下顎前牙區域的儀器以及測量方法，並且透過蒐集相當數量的人體牙周韌帶相關數據，可利用於未來人類牙齒有限元素分析之數值模擬的實驗驗證。
並列摘要
The periodontal ligament not only plays an important role in supporting the natural teeth in the alveolar bone, but also acts as an important structure to buffer excessive force to avoid the trauma of the teeth. Nowadays, dental implants used in the edentulous patients has become a fairly common treatment; however, due to the lack of a cushioning structure like periodontal ligament, many morbidities or even failure of dental implants had occurred after the long-term clinical follow up, for example: fixture fracture, prosthesis fracture, peri-implantitis, screw loosening, occlusal trauma, etc. Therefore, it is needed to investigate the biomechanical model of the periodontal ligament o and to develop new type of dental implants with a cushioning structure. Since the past literature have focused on the measurement of in vitro, the research results of in vivo measurement are lacking, so, the purpose of present study was to investigate the biomechanical behavior of the periodontal ligament of human tooth. The present study using precision measuring devices in a safe and non-invasive way to obtain the PDL of single-rooted tooth of the human. The source of the subjects was taken from the outpatient department of the Oral and maxillofacial surgery department of National Taiwan University Hospital. A random sampling method was used to collect ten eligible clinical subjects. A total of ten clinical subjects (males: 4, females: 6) with healthy periodontal condition were included. The research goal was to investigate the elastic modulus of the periodontal ligament and its biomechanical behavior model, and to verify whether the human PDL has the viscoelastic properties by performing load-displacement, creep, stress relaxation and hysteresis tests. The results show that the PDL has the characteristics of viscoelastic materials such as creep, stress relaxation, and hysteresis after the application of force, and it can be explained by Maxwell-Voigt model. In present study, we divided the natural teeth into three groups of 25 μm, 50 μm and 75 μm, and the average dissipated energy was 1.61±0.71, 3.98±2.14 and 11.29±4.12 (1×10-2 mJ). It shows that the average dissipated energy of the three groups shows a trend of increasing exponential relationship. The Young's modulus of PDL of the human single rooted tooth ranged from 0.068 MPa to 0.491 MPa, with an average of 0.231 MPa and a SD of 0.137 MPa. We use Chi-Square analysis for the Periotest M value(PTV) and the dissipated energy of the tested teeth in the 25 μm displacement group, and the score was 0.667 (>0.05) which indicated that there is no statistically significant difference between the PTV and the dissipated energy of the PDL. The PDL average deformation in the hysteresis loop after vertical displacement of 25 μm, 50 μm and 75 μm were 8.60±3.90 μm, 19.12±11.17 μm and 24.06±14.97 μm, respectively, indicating that the average deformation of the PDL presents upwards and is a quadratic function relationship. However, the average deformation rate is 44.56±18.74%, 47.06±26.96% and 43.30±20.65%, and the range falls between 43.3% and 44.56%, which is not affected by the magnitude of vertical displacement. Based on the results, it is pointed out that the human PDL has the properties of a viscoelastic material. The present study establishes a measuring devices and a measurement method for standardized measurement of the human lower anterior teeth, and we collects a considerable amount of data on the human PDL, which can be applied to the experimental verification of numerical simulation of EF model.
並列關鍵字
Periodontal Ligament ； Elastic Modulus ； Ligaments ； Human ； Lower incisors ； Viscoelasticity ； Dissipated Energy參考文獻
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