鑄造牙根柱不同邊緣修形之應力研究有限元素法應力分析

Stress Distribution on Different Marginal Preparations of Cast Post-Core – A Finite element Stress Analysis

王兆祥(Chau-Hsiang Wang) ； 李惠娥(Huey-Er Lee) ； 洪昭民(Jau-Min Hong)

《The Kaohsiung Journal of Medical Sciences》 3卷12期 (1987/12) Pp. 770-782

https://doi.org/10.6452/KJMS.198712.0770

摘要

鑄造牙根柱的邊緣修形有：（１）相對斜面、（２）雙斜面、（３）平面三種。本研究藉由平面有限元素應力分析法來分析上述三種不同鑄造牙根柱斜面在前牙及後牙於假設的各種施力狀況下，其應力分佈的情形。以做為臨床製作與使用的參考。其結果顯示：（１）三種不同邊緣修形的根柱，不論在前牙或後牙於各種施力下，應力分佈型態都有極高的相似性。（２）相對斜面在齒頸部的應力，除了在後牙承受垂直力時有較小的抗張應力外，其餘皆比其他兩種設計有更大的應力；其差值在前牙較大。（３）根柱根尖部的應力，前牙多集中在牙根舌側邊緣，後牙則呈頰舌側的變化。

並列摘要

The object of this study was to use plane stress analysis to survey the stress distribution of cast post-core in three different types of marginal preparations. The types of marginal preparations designed were contrabevel, biplaned and flat. Two-dimensional finite element models of the maxillary central incisor (anterior tooth) were subjected to a simulated biting force of 200 N which were applied approximately to various occlusal contact conditions. Stress on cervical (A-a plane) and post apex (B-b plane) were selected for comparsion.
Based on plane stress analysis, the maximun principal stress in the anterior tooth ranged from –4.526 MPa to 19.544 Mpa and that in the posterior tooth ranged from –2.746 MPa to 16.498 MPa. Stress distribution patterns of three marginal preparations were very alike especially on the post apex (B-b) plane. The maximum principal stress of contrabevel designed models were higher than the other two marginal preparations. Under vertical loading however the same design model in the posterior tooth showed a lower tensile stress in this experiment. It appears that an imaginary rotational center exists near the junction of the middle and apical third of the post-core, and that the rotational center is approximately located in the middle third of the roots in all types of cast post-core.

並列關鍵字

post and core ； contrabevel ； finite element stress analysis