下顎第一小臼齒近心鄰接面齒質缺損裝置牙根柱時之應力研究－有限元素法

Biomechanical analysis of post and core for mandibular first premolar with different proximal decay－ finite element method

戴晸昆(Chen-Kung Tai)

指導教授 ： 王兆祥

高雄醫學大學/口腔醫學院/牙醫學研究所/碩士(2008年)

https://doi.org/10.6832/KMU.2008.00085

摘要

根管治療後的牙齒常常使用牙根柱(post)強化對牙齒抗斷裂強度(fracture resistance)，其中牙齒殘存齒質多寡是影響齒質強度的主要因素。鄰接面齲齒(proximal caries)是導致牙齒需要進行根管治療的原因之一。因為鄰接面齲齒而進行治療的牙齒往往會在近心側(mesial side)或是遠心側(distal side)造成大範圍的齒質缺損，局部齒質缺損對牙齒影響的探討是較少的。本研究目的主要是利用電腦輔助分析方式，探討不同近心側齒質缺損牙齒裝置牙根柱時應力變化，以提供臨床診斷與治療參考之用。實驗以有限元素軟體(ANSYS)分析人類下顎第一小臼齒三維實體模型，模擬不同近心側齒質缺損(高度2 mm、1.5 mm、1.0 mm、0.5 mm、0 mm)受到不同方向咬合力時應力變化。咬合力設定為100 N且通過小臼齒頰側咬頭頂點，PV表示平行牙齒長軸的垂直咬合力、PB表示由頰側45度方向往舌側的側方咬合力、PL表示由舌側45度方向往頰側的側方咬合力、PM表示由近心45度方向往遠心側的側方咬合力、PD表示由遠心45度方向往近心側的側方咬合力。結果發現當受PV力時，牙根柱在殘缺齒質交角處應力會隨著齒質缺損越多而有明顯集中。而受到PB、PL力時牙齒近心端齒頸部會隨著齒質缺損一開始有應力下降現象，但隨著齒質缺損而不足1 mm後應力有明顯上升現象。本實驗得到結論：局部殘缺齒質在垂直力作用下會導致牙根柱與牙齒交角處應力集中現象，當近心端齒質缺損而不足1 mm時，頰、舌方向的咬合力會比近、遠心方向的咬合力影響更大，側方力對牙齒及牙根柱的影響比垂直力大。

關鍵字

牙根柱 ； 三維有限元素法 ； 殘存齒質

並列摘要

Abstract
Some reports point out the weakness of endodontically treated teeth, that it would reinforce the teeth by use of posts. However, residual tooth structure has major influence on resistance of tooth fracture. Teeth with proximal caries often need endodontic treatment. In those teeth, there are no tooth structure in mesial or distal side. Study for those situation is rare. The purpose of this study was to analyze the stress of post and core for mandibular first premolar with different mesial proximal decay during normal masticatory load by finite element method (FEM). In this study, the three-dimensional finite element method was employed to analyze the stress difficult to calculate by traditional clinical observation or experimental approaches. Solid models of the mandibular first premolar with five height of mesial tooth structure (2 mm, 1.5 mm, 1.0 mm, 0.5 mm, 0 mm) and casting post was build up. Solid model was transferred to the mesh model in FE package(ANSYS) to process the stress analysis. Five different force all 100 N were applied on buccal cusp tip: (1)PV: vertical force along tooth axis; (2)PB: 45 degree force from buccal to lingual direction. ; (3)PL: 45 degree force from lingual to buccal direction. ; (4)PM: 45 degree force from mesial to distal direction. ; (5)PD: 45 degree force from distal to mesial direction. The results showed that there are stress concentration increase in contact area between tooth and post with mesial tooth structure decrease in PV force. We also found that the stress decreased with mesial tooth structure decrease in PB and PL. But when tooth structure not enough of 1 mm, the stress concentrate increase observably. The conclusions of this study were that stress will concentrate in the area between post and tooth structure in PV force. PB and PL have more influence than PM and PDwhen proximal tooth structure loss. Lateral force has more influence on post and tooth structure than vertical force.

並列關鍵字

post ； finite element method ； residual tooth structure

參考文獻

參考文獻

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