title: Finite element analysis in defining the optimal shape and safety factor of retentive clasp arms of a removable partial denture.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Clinic for Dental Prosthetics, Faculty of Dental Medicine, University of Belgrade, Belgrade, Serbia. midents@yahoo.com
authors.forename: Miodrag
authors.initials: M
authors.lastname: Sćepanović
authors.affiliation: Clinic for Dental Prosthetics, Faculty of Dental Medicine, University of Belgrade, Belgrade, Serbia.
authors.forename: Ljiljana
authors.initials: L
authors.lastname: Tihacek-Sojić
authors.affiliation: Technical Vocational School, Belgrade, Serbia.
authors.forename: Milan
authors.initials: M
authors.lastname: Tasić
authors.affiliation: University of Belgrade, Belgrade, Serbia.
authors.forename: Radivoje
authors.initials: R
authors.lastname: Mitrović
authors.affiliation: Clinic for Dental Prosthetics, Faculty of Dental Medicine, University of Belgrade, Belgrade, Serbia.
authors.forename: Aleksandar
authors.initials: A
authors.lastname: Todorović
authors.affiliation: Clinic for Dental Prosthetics, Faculty of Dental Medicine, University of Belgrade, Belgrade, Serbia.
authors.forename: Branka
authors.initials: B
authors.lastname: Trifković
mesh_terms: D000080:Acetals; D002857:Chromium; D003035:Cobalt; D003198:Computer Simulation; D017076:Computer-Aided Design; D003722:Dental Alloys; D016734:Dental Clasps; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis; D003781:Denture Retention / Q000295:instrumentation*; D003832:Denture, Partial, Removable; D020342:Finite Element Analysis; D006801:Humans; D003765:Models, Dental; D008982:Molybdenum; D011108:Polymers; D012449:Safety; D014025:Titanium
chemical_list: D000080:Acetals; D003722:Dental Alloys; D011108:Polymers; D002857:Chromium; C016067:polyacetal; D003035:Cobalt; D008982:Molybdenum; D014025:Titanium