- 學位論文
下顎後牙區不同角度植體咬合功能時的應力分布之影響 --有限元素法
Stress Analysis of Angulated Dental Implant Installation— Finite Element Method
摘要
根據傳統的觀念，植體要相互平行且垂直咬合面的植入。因為臨床上的限制，常常發現有非相互平行的植體出現。本篇實驗主要是研究在咀嚼力下不同角度植體植入的骨應力分布。進而推論出更理想的植入角度。 我們使用三維有限元素模型來模擬下顎骨在第一、第二大臼齒區缺牙並植入植體的情形。根據單顆植體角度15°的偏差來做角度變化總計模擬九組模型，施力200N在贗復物牙橋的中心咬合窩上，方向分為垂直力、水平力（頰舌向）及斜向力45°(頰舌向及近遠心向)。 植體植入的角度有所傾斜並不一定都是壞的結果，就力量的分布而言，有些設計還優於平行植入的植體 ；就垂直施力而言，植體根尖稍微分開的組別（Model 2、 5、6)其應力表現是接近或更優於平行植入的組別（Model 1）；而在水平力的施予下，除了在第二大臼齒區遠心傾斜植入植體的組別（Model 4、9）表現出較高的壓應力值外，其餘各組的表現各組都差別不大。頰舌向45°斜向力的應力表現與水平力近似，而近遠心向45°斜向力的應力表現以植體根間分開的組別表現較佳（Model 2、5、6），其餘各組的表現都比平行植入的植體還差。 在臨床上常常有許多的理由來解釋植體角度的差異，特別是在後牙區。事實上，植體植入時在根尖的部分有稍微的外展也許是一個不錯的選擇，建議臨床醫師在手術板引導下先植入第二大臼齒區植體，確認角度的差異後再來植入第一大臼齒，並可由X ray知道預後情況。
並列摘要
According to the conventional concept, implants were installed to parallel with each other and perpendicular to occlusion plane. Due to clinical limitations, non-parallel implants occurred at times. The purpose of this study was focused on the bony stress distribution of different implant tilting under masticatory load. Furthermore, attempted to find the desirable installation angle of implant. The three-dimensional finite element models were constructed to simulate when mandibular first and second molar missing restored with implants. According to different angulation designs (15?a), nine solid models were built up. A simulating load (200N) was applied vertically、 horizontally(buccal-lingual direction) and obliquely45°（B-L direction and mesial-distal direction) on the occlusal central fossa of the bridge prostheses. Implant bodies tilting with the bridge prostheses not all got bad results. For stress distribution, some designs will be better than parallel installation. From the peak stress values , slightly divergent installed implants have near(model 2) or lower values (model 5&6); slightly convergent installed implants got higher values under vertical force. Under horizontal force, the peak values were close to each other, except the 2nd implant incline distally (model 4&9) .Under the oblique force of buccal-lingual direction, the results were similar to the horizontal force; the oblique force of mesial and distal direction, slightly divergent installed implants had lower values (model 2,5&6),the others had worse results than parallel installed implants (model 1). Clinically, there are many reasons to explain why implant tilting occur, especially over posterior area. Slightly non-parallel installation of implant bodies is may be a better choice. We suggested the clinician to install the implant over the second molar area first and check X ray first to decide the next step, and check another X ray after installing the other implant over the first molar area to get prognosis.