title: Bending properties of strengthened Ti-6Al-7Nb alloy major connectors compared to Co-Cr alloy major connectors.
abstract: BACKGROUND
  Although Ti-6Al-7Nb alloy has several excellent mechanical properties, its poor rigidity has limited its clinical use as a material for the fabrication of a removable partial denture (RPD) major connector.
  
  
  OBJECTIVE
  The purpose of this study was to develop and evaluate strengthening designs of Ti-6Al-7Nb RPD major connectors in an effort to increase rigidity.
  
  
  METHODS
  Four strengthening designs of Ti-6Al-7Nb alloy major connectors were developed using finite element analysis modeling: wide, thick, thick at the middle, and thick at the anterior and posterior borders. The designs had similar rigidity values to a conventional Co-Cr alloy major connector, as measured by the maximum deformation when a simulated load was applied. Next, 30 Kennedy Class II maxillary RPD specimens, using 6 different major connector designs (n = 5), were fabricated. These 6 designs included Ti-6Al-7Nb alloy RPDs with 4 different strengthening designs, a Ti-6Al-7Nb alloy RPD without strengthening designs, and a conventional Co-Cr alloy RPD as a control. The rigidity of the RPDs was evaluated by measuring strains on the major connector and force on the intaglio surface of a denture base under a 30 N loading condition. The data obtained from the 6 different RPD designs were compared using a repeated measures analysis of variance and the Bonferroni correction (alpha=.05).
  
  
  RESULTS
  The strains on the major connectors and the force on the denture bases measured from the Ti-6Al-7Nb RPD without strengthening designs were significantly larger than those of the standard Co-Cr alloy RPD. The strains measured from the 4 strengthening designs were not significantly larger than those of the Co-Cr alloy RPD.
  
  
  CONCLUSIONS
  The results suggest that the strengthening designs tested may improve the rigidity of the Ti-6Al-7Nb alloy major connectors and, hence, may promote clinical application for RPDs.
authors.affiliation: Removable Prosthodontics/Department of Masticatory Function Rehabilitation, Division of Oral Health Sciences/Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima Bunkyo-ku, Tokyo 113-8549, Japan. arirpro@tmd.ac.jp
authors.forename: Kumiko
authors.initials: K
authors.lastname: Aridome
authors.forename: Mayumi
authors.initials: M
authors.lastname: Yamazaki
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Baba
authors.forename: Takashi
authors.initials: T
authors.lastname: Ohyama
mesh_terms: D002858:Chromium Alloys / Q000737:chemistry*; D003198:Computer Simulation; D003722:Dental Alloys / Q000737:chemistry*; D003819:Denture Bases; D003779:Denture Design; D003832:Denture, Partial, Removable; D004548:Elasticity; D020342:Finite Element Analysis; D006801:Humans; D008422:Materials Testing; D008956:Models, Chemical; D018583:Pliability; D013314:Stress, Mechanical; D014025:Titanium / Q000737:chemistry*
chemical_list: D002858:Chromium Alloys; D003722:Dental Alloys; C070282:Ti-6Al-7Nb alloy; D014025:Titanium