Department of Oral Implantology, Faculty of Dentistry, Veiga de Almeida University, Rio de Janeiro, Brazil.
Implant Dent. 2010 Feb;19(1):39-49. doi: 10.1097/ID.0b013e3181cc7ffc.
The objective of this study was to evaluate the stress on the cortical bone around single body dental implants supporting mandibular complete fixed denture with rigid (Neopronto System-Neodent) or semirigid splinting system (Barra Distal System-Neodent).
Stress levels on several system components were analyzed through finite element analysis. Focusing on stress concentration at cortical bone around single body dental implants supporting mandibular complete fixed dentures with rigid (Neopronto System-Neodent) or semirigid splinting system (Barra Distal System-Neodent), after axial and oblique occlusal loading simulation, applied in the last cantilever element.
The results showed that semirigid implant splinting generated lower von Mises stress in the cortical bone under axial loading. Rigid implant splinting generated higher von Mises stress in the cortical bone under oblique loading.
It was concluded that the use of a semirigid system for rehabilitation of edentulous mandibles by means of immediate implant-supported fixed complete denture is recommended, because it reduces stress concentration in the cortical bone. As a consequence, bone level is better preserved, and implant survival is improved. Nevertheless, for both situations the cortical bone integrity was protected, because the maximum stress level findings were lower than those pointed in the literature as being harmful. The maximum stress limit for cortical bone (167 MPa) represents the threshold between plastic and elastic state for a given material. Because any force is applied to an object, and there is no deformation, we can conclude that the elastic threshold was not surpassed, keeping its structural integrity. If the force is higher than the plastic threshold, the object will suffer permanent deformation. In cortical bone, this represents the beginning of bone resorption and/or remodeling processes, which, according to our simulated loading, would not occur.
本研究的目的是评估刚性（Neopronto 系统-Neodent）或半刚性夹板系统（Barra Distal 系统-Neodent）支持下颌全固定义齿的单个种植体对皮质骨的应力。
通过有限元分析分析了几个系统组件的应力水平。重点关注刚性（Neopronto 系统-Neodent）或半刚性夹板系统（Barra Distal 系统-Neodent）支持下颌全固定义齿的单个种植体的皮质骨的应力集中，在轴向和斜向咬合加载模拟后，施加在最后一个悬臂元件上。
结果表明，半刚性种植体夹板在轴向加载下皮质骨的 von Mises 应力较低。刚性种植体夹板在斜向加载下皮质骨的 von Mises 应力较高。
因此，建议使用半刚性系统对无牙颌下颌进行修复，通过即刻种植体支持的固定全口义齿，因为它可以减少皮质骨中的应力集中。因此，骨水平得到更好的保留，植入物的存活率得到提高。然而，对于这两种情况，皮质骨的完整性都得到了保护，因为最大的应力水平低于文献中指出的有害水平。皮质骨的最大应力极限（167 MPa）代表了给定材料的塑性和弹性状态之间的阈值。由于任何力都作用于物体，并且没有变形，我们可以得出结论，弹性阈值没有超过，保持其结构完整性。如果力高于塑性阈值，物体将发生永久变形。在皮质骨中，这代表了骨吸收和/或重塑过程的开始，根据我们的模拟加载，这些过程不会发生。
