title: Fatigue strength of Co-Cr-Mo alloy clasps prepared by selective laser melting.
abstract: We aimed to investigate the fatigue strength of Co-Cr-Mo clasps for removable partial dentures prepared by selective laser melting (SLM). The Co-Cr-Mo alloy specimens for tensile tests (dumbbell specimens) and fatigue tests (clasp specimens) were prepared by SLM with varying angles between the building and longitudinal directions (i.e., 0° (TL0, FL0), 45° (TL45, FL45), and 90° (TL90, FL90)). The clasp specimens were subjected to cyclic deformations of 0.25mm and 0.50mm for 10(6) cycles. The SLM specimens showed no obvious mechanical anisotropy in tensile tests and exhibited significantly higher yield strength and ultimate tensile strength than the cast specimens under all conditions. In contrast, a high degree of anisotropy in fatigue performance associated with the build orientation was found. For specimens under the 0.50mm deflection, FL90 exhibited significantly longer fatigue life (205,418 cycles) than the cast specimens (112,770 cycles). In contrast, the fatigue lives of FL0 (28,484 cycles) and FL45 (43,465 cycles) were significantly shorter. The surface roughnesses of FL0 and FL45 were considerably higher than those of the cast specimens, whereas there were no significant differences between FL90 and the cast specimens. Electron backscatter diffraction (EBSD) analysis indicated the grains of FL0 showed preferential close to <001> orientation of the γ phase along the normal direction to the fracture surface. In contrast, the FL45 and FL90 grains showed no significant preferential orientation. Fatigue strength may therefore be affected by a number of factors, including surface roughness and crystal orientation. The SLM process is a promising candidate for preparing tough removable partial denture frameworks, as long as the appropriate build direction is adopted.
authors.affiliation: Removable Partial Prosthodontics, Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Kajima
authors.affiliation: Removable Partial Prosthodontics, Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. Electronic address: a.takaichi.rpro@tmd.ac.jp.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Takaichi
authors.affiliation: Machining & Molding Section, Technology Research Institute of Osaka Prefecture, 2-7-1 Ayumino, Izumi, Osaka 594-1157, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nakamoto
authors.affiliation: Machining & Molding Section, Technology Research Institute of Osaka Prefecture, 2-7-1 Ayumino, Izumi, Osaka 594-1157, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kimura
authors.affiliation: Removable Partial Prosthodontics, Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Yogo
authors.affiliation: Metallic Biomaterials, Biomedical Materials, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-surugadai, Chiyoda-ku, Tokyo 101-0062, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Ashida
authors.affiliation: Metallic Biomaterials, Biomedical Materials, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-surugadai, Chiyoda-ku, Tokyo 101-0062, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Doi
authors.affiliation: Metallurgy, Materials Science and Materials Processing, Graduate School of Engineering, Tohoku University, 6-6-02 Aramaki-aza Aoba, Aoba-ku, Sendai, Miyagi 980-8579, Japan.
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Nomura
authors.affiliation: Oral Biomaterials Development Engineering, Course for Oral Health Engineering, School of Oral Health Care Sciences, Faculty of Dentistry, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Metallic Biomaterials, Biomedical Materials, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-surugadai, Chiyoda-ku, Tokyo 101-0062, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Hanawa
authors.affiliation: Removable Partial Prosthodontics, Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Wakabayashi
mesh_terms: D002858:Chromium Alloys; D003722:Dental Alloys; D016734:Dental Clasps; D003799:Dental Stress Analysis; D003832:Denture, Partial, Removable; D008422:Materials Testing; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D002858:Chromium Alloys; D003722:Dental Alloys
keywords: Anisotropy; Clasp; Co–Cr–Mo alloy; Fatigue strength; Removable partial denture; Selective laser melting