Magne Pascal, Belser Urs C
Department of Prosthodontics, School of Dental Medicine, University of Geneva, Switzerland.
Int J Periodontics Restorative Dent. 2003 Dec;23(6):543-55.
This study used 2-D finite element modeling to simulate cuspal flexure and stresses at the surface and tooth-restoration interface of a restored maxillary molar using three restorative materials; the influence of four inlay/onlay preparation configurations on stress distribution within the complex was also investigated. A buccolingual cross-section of an intact molar was digitized and used to create 2-D models restored with different restorative materials (feldspathic porcelain, high- and low-elastic modulus composites) and tooth preparations (small and large inlays, small and large onlays). Two simulated 25-N oblique loads were applied to the cusps. The tangential stress for each finite element node located at the tooth surface, interfacial stress, and relative cuspal flexure were analyzed. All materials and tooth preparations exhibited similar surface tangential stress patterns, with a definite compressive area at the external cusp ridges, a tensile zone at the occlusal surface, and compression stress peaks at the CEJ. The low-elastic modulus composite showed reduced tensile stresses at its surface but increased tension at the dentin-adhesive interface when compared to ceramics. All types of onlays demonstrated a majority of compressive interfacial stresses, while inlays showed a majority of tensile stresses. The interfacial tension at the dentin level increased with the flexibility of the restorative material. Only the large ceramic onlay displayed almost pure compression at the interface. Composite-restored teeth exhibited increased crown flexure, while porcelain-restored teeth showed increased crown stiffness. Porcelain inlays/onlays featured more detrimental stresses at the occlusal surface but better potential protection against debonding at the dentin-restoration interface compared to composite inlays/onlays. Ceramic onlays/overlays seem to represent an effective answer to restore severely damaged posterior teeth.
本研究采用二维有限元建模，使用三种修复材料模拟上颌磨牙修复体的牙尖挠曲以及表面和牙齿-修复体界面处的应力；还研究了四种嵌体/高嵌体预备形态对该复合体内部应力分布的影响。对完整磨牙的颊舌向横截面进行数字化处理，以创建用不同修复材料（长石质瓷、高弹性模量和低弹性模量复合材料）和牙齿预备（小和大嵌体、小和大高嵌体）修复的二维模型。对牙尖施加两个模拟的25 N斜向载荷。分析位于牙齿表面的每个有限元节点的切向应力、界面应力和相对牙尖挠曲。所有材料和牙齿预备均呈现相似的表面切向应力模式，在外牙尖嵴处有明确的压缩区域，在咬合面有拉伸区，在牙骨质牙本质界处有压缩应力峰值。与陶瓷相比，低弹性模量复合材料表面的拉应力降低，但在牙本质-粘结剂界面处的拉应力增加。所有类型的高嵌体均表现出大部分为压缩性的界面应力，而嵌体则表现出大部分为拉伸应力。牙本质水平的界面张力随修复材料的柔韧性增加而增加。只有大的陶瓷高嵌体在界面处几乎呈现纯压缩。复合材料修复的牙齿表现出冠部挠曲增加，而瓷修复的牙齿表现出冠部刚度增加。与复合材料嵌体/高嵌体相比，瓷嵌体/高嵌体在咬合面具有更有害的应力，但在牙本质-修复体界面处具有更好的防止脱粘的潜力。陶瓷高嵌体/覆盖体似乎是修复严重受损后牙的有效解决方案。
