Influence of incisal length of ceramic and loading orientation on stress distribution in ceramic crowns.
Influence of incisal length of ceramic and loading orientation on stress distribution in ceramic crowns.
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陶瓷切缘长度和加载方向对陶瓷冠应力分布的影响。
DOI：
10.1177/00220345880670110201
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发表时间：
1988
影响因子：
7.6
通讯作者：
Hojjatie,B
中科院分区：
文献类型：
--
作者：
Anusavice,KJ;Hojjatie,B
对于陶瓷冠，建议减牙深度距前牙切缘1.5毫米至2. 0毫米。尽管一些口腔修复专家认为，超过 2 毫米的陶瓷切牙高度与危险的高口腔内应力有关，但这一理论尚未得到证实。本研究的目的是检验这样的假设：为准备好的上颌中切牙设计的陶瓷牙冠的应力分布对陶瓷切牙长度相对不敏感。对三种牙冠设计进行有限元应力分析，沿着切缘附近的舌面施加 200 N 的水平或垂直力。上颌中切牙陶瓷牙冠的切牙长度分别为 1.0 毫米（案例 I）、1.9 毫米（案例 II）和 4.0 毫米（案例 III）。每种情况均包含膜厚为 30 μm 的磷酸锌水泥。平面应力有限元分析表明，对于牙冠三分之一牙龈内的所有三种情况，由于垂直施加的 200 N 载荷而在水泥和陶瓷中产生的拉应力和压应力的大小相当。对于情况 I、II 和 III，水泥中面部区域的拉应力分别为 6.7、5.4 和 6.5 MPa，陶瓷中的拉应力分别为 46.2、48.6 和 49.2 MPa。这项研究的结果倾向于支持以下假设：切齿方向的牙齿减少量（1 至 4 毫米）不会显着影响牙冠或水泥层的应力分布。事实上，所施加载荷的方向是比牙冠或备牙的几何形状更重要的因素。
For ceramic crowns, the recommended depth of tooth reduction from the incisal edge of anterior teeth is 1.5 mm to 2. 0 mm. Although some prosthodontists have suggested that incisal heights of ceramic which exceed 2 mm are associated with dangerously high intra-oral stresses, this theory has not been verified. The objective of this study was to test the hypothesis that the stress distribution in ceramic crowns designed for a prepared maxillary central incisor which are subjected to applied loading is relatively insensitive to the incisal length of ceramic. Finite element stress analyses were performed on three crown designs loaded with a horizontal or vertical force of 200 N along the lingual surface near the incisal edge. Ceramic crowns for maxillary central incisors were modeled with incisal lengths of 1.0 mm (Case I), 1.9 mm (Case II), and 4.0 mm (Case III). Zinc phosphate cement with a film thickness of 30 μm was included for each case. Plane-stress finite element analyses indicated that tensile and compressive stresses which were induced in cement and ceramic due to a vertically applied load of 200 N were comparable in magnitude for all three cases within the gingival third of the crowns. For Cases I, II, and III, tensile stresses at the facial region were 6.7, 5.4, and 6.5 MPa, respectively, in cement and 46.2, 48.6, and 49.2 MPa, respectively, in the ceramic. The results of this study tend to support the hypothesis that the amount of tooth reduction (1 to 4 mm) in an incisogingival direction does not significantly influence the stress distribution in the crown or cement layer. In fact, the orientation of the applied load is a more significant factor than the geometry of the crown or prepared tooth.