Koutayas Spiridon Oumvertos, Kern Matthias, Ferraresso Franco, Strub Jörg Rudolf
Department of Prosthodontics, Propaedeutics and Dental Materials, School of Dentistry, Christian-Albrechts University, Kiel, Germany.
Int J Prosthodont. 2002 May-Jun;15(3):223-9.
The purpose of this in vitro study was to evaluate the influence of the framework design on the fracture strength of all-ceramic resin-bonded fixed partial dentures (RBFPD) in the mandibular incisor region.
Twenty-four aluminum oxide ceramic frameworks were copy milled with the Celay system, glass infiltrated, and veneered with feldspathic porcelain to replace a mandibular incisor. Forty-eight extracted human incisors were used as abutments by embedding them in a polyester resin. The master casts were fabricated according to a typical clinical case. The sandblasted restorations were bonded to the acid-etched abutment teeth with a composite resin. Twelve RBFPDs had a conventional two-retainer design, and 12 had a cantilevered single-retainer design. Subgroups of eight specimens were subjected to a quasistatic load in the direction of the long axis of the abutment teeth in a universal testing machine. Additional subgroups of four specimens were subjected under 0 degrees to dynamic loading of 25 N in a dual-axis chewing simulator.
The mean fracture strengths under quasistatic loading were 313 N (SD 42) for the two-retainer design and 291 N (SD 100) for the single-retainer design. The mean cycles sustained by specimens subjected to dynamic loading at 25 N were 50,081 (SD 42,705) for the two-retainer design and 297,099 (SD 508,439) for the single-retainer design. There was no statistically significant influence of the framework design on the fracture strength of the restorations under quasistatic or dynamic loading.
The clinical application of cantilevered all-ceramic RBFPDs in the mandible may be an alternative to all-ceramic RBFPDs with two retainers.
本体外研究的目的是评估支架设计对下颌切牙区全瓷树脂粘结固定局部义齿（RBFPD）断裂强度的影响。
采用Celay系统复制铣削24个氧化铝陶瓷支架，进行玻璃渗透，并用长石质瓷进行饰面，以替代下颌切牙。将48颗拔除的人类切牙嵌入聚酯树脂中作为基牙。根据典型临床病例制作主模型。将喷砂处理后的修复体用复合树脂粘结到酸蚀后的基牙上。12个RBFPD采用传统的双固位体设计，12个采用悬臂单固位体设计。在万能试验机中，将8个样本的亚组沿基牙长轴方向施加准静态载荷。另外4个样本的亚组在双轴咀嚼模拟器中于0度下承受25 N的动态载荷。
双固位体设计在准静态载荷下的平均断裂强度为313 N（标准差42），单固位体设计为291 N（标准差100）。在25 N动态载荷下，双固位体设计样本的平均循环次数为50,081（标准差42,705），单固位体设计为297,099（标准差508,439）。在准静态或动态载荷下，支架设计对修复体的断裂强度没有统计学上的显著影响。
下颌悬臂式全瓷RBFPD的临床应用可能是双固位体全瓷RBFPD的一种替代方案。
