Effect of adding support structures for overhanging part on fatigue strength in selective laser melting

Yuka Kajima; Atsushi Takaichi; Takayuki Nakamoto; Takahiro Kimura; Nuttaphon Kittikundecha; Yusuke Tsutsumi; Naoyuki Nomura; Akira Kawasaki; Hidekazu Takahashi; Takao Hanawa; Noriyuki Wakabayashi

doi:10.1016/j.jmbbm.2017.11.009

Effect of adding support structures for overhanging part on fatigue strength in selective laser melting

J Mech Behav Biomed Mater. 2018 Feb:78:1-9. doi: 10.1016/j.jmbbm.2017.11.009. Epub 2017 Nov 6.

Affiliations

¹ 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.
² 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.
³ Research Division of Machining and Molding, Osaka Research Institute of Industrial Science and Technology Izumi Center, 2-7-1 Ayumino, Izumi, Osaka 594-1157, Japan.
⁴ 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.
⁵ 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.
⁶ Department of Oral Biomaterials Engineering, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.

PMID: 29128693
DOI: 10.1016/j.jmbbm.2017.11.009

Abstract

Selective laser melting (SLM) technology was recently introduced to fabricate dental prostheses. However, the fatigue strength of clasps in removable partial dentures prepared by SLM still requires improvement. In this study, we attempted to improve the fatigue strength of clasps by adding support structures for overhanging parts, which can generally be manufactured at an angle to be self-supporting. The results show that the fatigue strength of the supported specimens was more than twice that of unsupported specimens. Electron back-scattered diffraction analysis revealed that the supported specimens exhibited lower kernel average misorientation values than the unsupported specimens, which suggested that the support structure reduced the residual strain during the SLM process and helped to prevent micro-cracks led by thermal distortion. In addition, the supported specimens cooled more rapidly, thereby forming a finer grain size compared to that of the unsupported specimens, which contributed to improving the fatigue strength. The results of this study suggest that the fatigue strength of overhanging parts can be improved by intentionally adding support structures.

Keywords: Clasp; Co–Cr–Mo alloy; Fatigue strength; Finite element simulation; Selective laser melting; Support structure.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Dental Clasps*
Finite Element Analysis
Lasers*
Materials Testing
Mechanical Phenomena*
Prosthesis Design*
Stress, Mechanical
Surface Properties