Sćepanović Miodrag, Tihacek-Sojić Ljiljana, Tasić Milan, Mitrović Radivoje, Todorović Aleksandar, Trifković Branka
Clinic for Dental Prosthetics, Faculty of Dental Medicine, University of Belgrade, Belgrade, Serbia.
Technical Vocational School, Belgrade, Serbia.
Vojnosanit Pregl. 2013 Nov;70(11):999-1005. doi: 10.2298/vsp110526021s.
BACKGROUND/AIM: Retentive force of removable partial denture (RPD) directly depends on elastic force of stretched retentive clasp arms (RCAs). During deflection RCA must have even stress distribution. Safety factor is the concept which can be applied in estimating durability and functionality of RCAs. This study was based on analyzing properties of clasps designed by conventional clasp wax profiles and defining the optimal shapes of RCAs for stress distribution and safety factor aspects.
Computer-aided-design (CAD) models of RCAs with simulated properties of materials used for fabrication of RPD cobalt-chromium-molybdenum (CoCrMo) alloy, commercially pure titanium (CPTi) and polyacetale were analzed.
The research showed that geometrics of Rapidflex profiles from the BIOS concept are defined for designing and modeling RCAs from CoCrMo alloys. I-Bar and Bonihard clasps made from CPTi might have the same design as Co-CoCrMo clasp only by safety factor aspect, but it is obvious that CPTi are much more flexible, so their shape must be more massive. Polyacetale clasps should not be fabricated by BIOS concept for CoCrMo alloy. A proof for that is the low value of safety factor.
The BIOS concept should be used only for RCAs made of CoCrMo alloy and different wax profiles should be used for fabricating clasps of other investigated materials. The contribution of this study may be the improve ment of present systems for defining the clasps shapes made from (CoCrMo alloys. The more significant application is the possibility of creating new concepts in defining shapes of RCA made from CPTi and polyacetale.
背景/目的：可摘局部义齿（RPD）的固位力直接取决于伸展的固位卡环臂（RCA）的弹力。在挠曲过程中，RCA必须具有均匀的应力分布。安全系数是一个可用于评估RCA耐久性和功能的概念。本研究基于分析传统卡环蜡型设计的卡环特性，并从应力分布和安全系数方面确定RCA的最佳形状。
分析了具有用于制造RPD的钴铬钼（CoCrMo）合金、商业纯钛（CPTi）和聚缩醛材料模拟特性的RCA的计算机辅助设计（CAD）模型。
研究表明，BIOS概念中的Rapidflex型的几何形状是为CoCrMo合金的RCA设计和建模而定义的。仅从安全系数方面来看，由CPTi制成的I型杆和Bonihard卡环可能与Co-CoCrMo卡环具有相同的设计，但很明显CPTi更具柔韧性，因此其形状必须更厚实。聚缩醛卡环不应按照BIOS概念用于CoCrMo合金。安全系数值较低就是证明。
BIOS概念仅应用于由CoCrMo合金制成的RCA，对于其他研究材料的卡环制造应使用不同的蜡型。本研究的贡献可能在于改进当前定义由CoCrMo合金制成的卡环形状的系统。更重要的应用是有可能在定义由CPTi和聚缩醛制成的RCA形状方面创造新的概念。
