下顎缺損腓骨重建與牙根支撐式局部義齒之生物力學分析

Biomechanical analysis of fibular reconstruction and implant-supported partial denture in mandibular defects

洪君豪(Jun-Hao Hung)

指導教授 ： 劉保興

義守大學/醫學院/生物醫學工程學系/碩士(2016年)

摘要

下顎缺損重建最大目的是恢復病患顏面缺陷以及矯正發音與恢復咀嚼等功能。臨床醫師使用重建骨板、骨釘及腓骨塊進行手術，最後再使用人工牙根搭配假牙完成重建手術。由於下顎缺損搭配牙根假牙重建後之生物力學影響並不明確，加上牙根數量、牙根分佈、下顎缺損範圍、腓骨數量與咬合力位置的參數影響也不清楚。因此，本研究的主要目的是利用三維有限元素分析探討八種下顎骨缺損範圍依照不同腓骨重建形式(數量)、不同咬合施力位置以及牙根植體的數量與分佈進行比較，以了解整體下顎骨的穩定度以及應力分佈之生物力學影響。有限元素模型包含下顎骨、腓骨、重建骨板、骨釘、牙根植體以及假牙，其中下顎骨與腓骨包含皮質骨與海綿骨，植體包含根部與支台結構。腓骨重建形式分為工程規劃與臨床規劃，咬合施力位置分為門齒區及臼齒區。邊界條件設為下顎髁狀突頸部區域為固定設定，咬合負載在大臼齒向內側中心線夾15 度角咬合力300N 以及門齒向外側中心線夾50 度角咬合力150N。
結果顯示隨著缺損範圍從小至大時，植入牙根植體的數量與位置分布的差異會隨著缺損範圍越大而越具有影響，並且缺損範圍較小時，須先考量植入植體的位置分布，缺損範圍較大時，則須先考量植入植體的數量大小。探討植入植體數量與缺損範圍關係時，發現牙根植體與假牙應力值呈現正比關係，增加植體數量對於應力傳遞較良好；腓骨應變值則呈現反比關係，缺損範圍增大時植體數量增加使得骨頭穩定度下降。選擇植入植體位置時，整體而言植體分布若較分散能降低牙根植體與假牙應力集中情形，以及提高骨頭穩定性。除此之外，探討植體位置於不同咬合施力位置的結果，發現植入植體位置越靠近咬合力位置時，對於假牙上產生的力矩較小，能減少蹺蹺板效應發生。比較門齒咬合施力與臼齒咬合施力結果時，整體發現門齒施力的結果較好，原因為人體咀嚼運動主要使用牙齒區域為臼齒區，因此相對在門齒的咬合力較小；且牙弓形狀為一個馬蹄形形狀，施力在單側邊臼齒對於假牙應力傳遞較不連續。探討不同腓骨重建方式結果，發現不論比較缺損範圍、咬合力位置、植體數量與位置之差異下，兩種腓骨重建方式對於植體與假牙的應力集中影響不大；但考量骨頭穩定度時，選擇臨床腓骨排列方式顯示較好趨勢。

關鍵字

有限元素分析 ； 下顎骨缺損 ； 人工牙根 ； 腓骨移植

並列摘要

Reconstruction of the mandibular defects is the main purpose of the correction of facial defects, the restoration of the pronunciation and the recovery of masticatory functions. Reconstruction plate, bone screws and fibular blocks were used in first stage surgery by clinicians, and then the dental implants combination with denture were also applied to accomplish the surgery of the mandibular defects. The biomechanical effects of the mandibular defect reconstruction by dental implant supported with denture were not clear. Furthermore, the distribution and number of the dental implant, defect regions, fibula blocks and points of the biting force were not also understood. Therefore, the main purpose of this study is to investigate biomechanical effects of the stability and stress distribution of the mandibular defect reconstruction to compare eight kinds of mandibular defect ranges, different layouts of fibular blocks, biting force positions as well as the number and distribution of dental implants using three-dimensional finite element analysis. The finite element model was consisted of defected mandible, fibula block, bone plate, screw, dental implant and denture, in addition to the mandible and fibula of the FE model contained cortical and cancellous structure, in the dental implant had two parts of abutment and root structures. Fibular layouts were divided into engineer and clinical considerations, and occlusal forces were applied at the two positions of incisor and molar. Boundary condition was fixed on the mandibular condylar neck regions, occlusal forces were 300N and 150N at the 15 degree with axis toward medial side in the molar and 50 degree with axis toward lateral side in the incisor respectively.
The results showed that based on defected ranges from small to large changes biomechanical effects of the number and distribution of the dental implant were more significant by accompanying increase of the defected range, moreover, the distribution of dental implant revealed important for reconstruction if defect range was small, on the other hand, the number of the dental implant was considered important if defect range of the mandible was large. To investigate relationship between implant number and defected ranges, increase of the implant number showed a better tendency in the stress distribution, but the strain index in the fibula was inversely proportional to the increase of the defected range, increasing defected range the stability showed decrease tendency when dental implant were increase. Consideration in the implant distribution, the stress concentration effect in the both implant and denture could be reduced if implant insertion were more separated and to enhance the stability of the mandibular defect reconstruction. In addition, to investigate the effect of the implant distribution in different occlusal forces, the results found that the implant insertion near to biting point could produce a smaller moment arm in the denture in order to reduce the seesaw effect. Further comparing different occlusal forces in the incisor and molar, a biting force in the incisor showed a better performance due to less magnitude in the biting force, moreover, a horseshoe shape of the dentition arch was not suitable for transfer and balance stress effect when unilateral biting force was occluded. For different layout types in the fibular blocks investigation, there were not significantly different in the stress concentration influence of the implant and the denture by comparing engineer and clinic fibular layouts in the parameters of defected ranges, biting points, implant number and implant distribution, but considering the bone stability, clinical fibular arrangement revealed a respectable tendency for the mandibular defect reconstruction.

並列關鍵字

Finite element analysis ； Mandibular defect ； Dental implant ； Fibular transplantation

參考文獻

[2] Available：

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[4] Available：

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