Petrikas O A, Voroshilin Iu G, Petrikas I V
Stomatologiia (Mosk). 2013;92(2):50-2.
Fiber-reinforced composite (FRC) fixed partial dentures (FPD) have become an accepted part of the restorative dentist's armamentarium. The aim of this study was to evaluate in vitro the influence of retainer design on the strength of two-unit cantilever resin-bonded glass FRC-FPDs. Four retainer designs were tested: a dual wing, a dual wing + horizontal groove, a dual wing + occlusal rest and a step-box. Of each design on 7 human mandibular molars, FRC-FPDs of a premolar size were produced. The FRC framework was made of resin Revolution (Kerr) impregnated glass fibers (GlasSpan, GlasSpan) and veneered with hybrid resin composite (Charisma, Kulzer). Revolution (Kerr) was used as resin luting cement. FRC-FPDs were loaded to failure in a universal testing machine. T (Student's)-test was used to evaluate the data. The four designs were analyzed with finite element analysis (FEA) to reveal the stress distribution within the tooth/restoration complex. Significantly lower fracture strengths were observed with inlay-retained FPDs (step-box: 172±11 N) compared to wing-retained FPDs (p<0.05) (a dual wing + horizontal groove 222±9 N). The highest fracture strengths were observed with dual wing + occlusal rest FPDs: 250±10 N compared to inlay-retained FPDs (p<0.001) and wing-retained FPDs (p<0.001). FEA showed more favorable stress distributions within the tooth/restoration complex for dual wing retainers+ occlusal rest FPDs. There was stress concentration around connectors and retainers near connectors. A dual-wing retainer with occlusal rest is the optimal design for replacement of a single premolar by means of a two-unit cantilever FRC-FPDs.
纤维增强复合材料（FRC）固定局部义齿（FPD）已成为修复牙医常用器械的一部分。本研究的目的是在体外评估固位体设计对双单位悬臂树脂粘结玻璃FRC-FPD强度的影响。测试了四种固位体设计：双翼型、双翼+水平沟型、双翼+支托型和阶梯盒型。在7颗人类下颌磨牙上制作了每种设计的前磨牙大小的FRC-FPD。FRC框架由Revolution（ Kerr公司）树脂浸渍玻璃纤维（GlasSpan公司，GlasSpan产品）制成，并用混合树脂复合材料（Charisma，Kulzer公司）进行贴面。Revolution（Kerr公司）用作树脂粘结水门汀。FRC-FPD在万能试验机上加载至破坏。采用t检验（学生检验）评估数据。对这四种设计进行有限元分析（FEA），以揭示牙齿/修复复合体内部的应力分布。与翼式固位的FPD相比（双翼+水平沟型：222±9N），嵌体固位的FPD（阶梯盒型：172±11N）观察到显著更低的断裂强度（p<0.05）。双翼+支托型FPD观察到最高的断裂强度：与嵌体固位的FPD相比为250±10N（p<0.001），与翼式固位的FPD相比（p<0.001）。有限元分析显示，对于双翼固位体+支托型FPD，牙齿/修复复合体内部的应力分布更有利。在连接体周围和连接体附近的固位体周围存在应力集中。带支托的双翼固位体是通过双单位悬臂FRC-FPD替代单个前磨牙的最佳设计。
