Crown retention. Part I. Stress analysis of symmetric restorations
Crown retention. Part I. Stress analysis of symmetric restorations
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表冠固位。
DOI：
10.1016/0022-3913(74)90053-5
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发表时间：
1974
期刊：
影响因子：
--
通讯作者：
J. Nicholls
中科院分区：
文献类型：
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作者：
J. Nicholls
全金冠修复对于牙齿修复变得越来越重要；因此，了解此类修复体的保持特性非常重要。考夫曼及其合著者和乔根森2已经开展了这一领域的工作，但这些研究人员已经根据从匹配制剂中去除几何指定的圆形圆锥形牙冠所需的负载来定义问题。虽然此类实验清楚地表明了要提供良好的保留效果必须避免的一些要点，但它并没有明确失败或失去保留的主要原因。从设计的角度来看，如果可以确定早期失效的原因，则可以在将来采取措施避免这种情况。发生失效后，在牙齿结构和金修复体的两个表面上都可以找到粘合剂，这一事实使我们得出这样的结论：失效发生在水泥层内，而不是发生在水泥和牙齿之间或水泥和修复体之间的界面之一。这反过来又让我们假设水泥层中产生的应力会导致断裂，最终导致固位力丧失。与固位问题相关的任何研究的目的都应该是确定这些应力，如果可能的话，确定是否可以找到最佳几何形状，最大限度地减少这些应力，以防止水泥层失效。
C omplete gold crown restorations have become increasingly important for restoring teeth; thus a knowledge of the retentive properties of this type of restoration is important. Work in this area has been carried out by Kaufman and co-authors’ and Jorgensen2 but these investigators have defined the problem in terms of the load required to remove a geometrically specified, circular, conical crown shape from a matching preparation. While this type of experiment clearly indicates some of the points which must be avoided if good retention is to be provided, it does not define the primary reason for failure or loss of retention. From a design standpoint, if the cause of an early failure can be ascertained, steps can be taken to avoid this in the future.The fact that the cementing agent between tooth structure and the gold restoration can be found on both of these surfaces after a failure has occurred leads us to the conclusion that failure occurs within the cement layer-not at one of the interfaces between cement and tooth or between the cement and restoration. This, in turn, leads us to presuppose that the stresses induced in the cement layer cause fracture which ultimately causes a loss of retention. The object of any investigation involved with the retention problem should then be to determine these stresses and, if possible, to determine if an optimum geometry can be found which minimizes these stresses to prevent failure of the cement layer.