Lertchirakarn Veera, Palamara Joseph E A, Messer Harold H
School of Dental Science, University of Melbourne, Victoria, Australia.
J Endod. 2003 Aug;29(8):523-8. doi: 10.1097/00004770-200308000-00008.
Previous studies have indicated that vertical root fracture tends to occur in a buccolingual direction, where dentin thickness is greatest. Factors potentially influencing the location and direction of root fracture include root canal shape, external root morphology, and dentin thickness. In this finite-element study, simulated root sections were varied systematically with respect to canal size and shape, external root morphology, and dentin thickness to determine their relative contribution to vertical root fracture. Similar models were constructed based on cross-sections of human tooth roots that had been fractured clinically or experimentally. Finite-element models demonstrated that canal curvature seems more important than external root morphology, in terms of stress concentration, and that reduced dentin thickness increases the magnitude but not the direction of maximum tensile stress. Models based on actual root fractures showed a strong similarity between tensile-stress distribution and fracture patterns.
以往研究表明，垂直根折往往沿颊舌向发生，此处牙本质厚度最大。可能影响根折位置和方向的因素包括根管形态、牙根外部形态和牙本质厚度。在这项有限元研究中，模拟牙根截面在根管大小和形态、牙根外部形态以及牙本质厚度方面进行了系统变化，以确定它们对垂直根折的相对影响。基于临床或实验中发生根折的人类牙根横截面构建了类似模型。有限元模型表明，就应力集中而言，根管曲率似乎比牙根外部形态更重要，并且牙本质厚度减小会增加最大拉应力的大小，但不会改变其方向。基于实际根折的模型显示拉应力分布与骨折模式之间有很强的相似性。
