Abstract
Statement of problem
The forces exerted on teeth and prostheses during mastication are repeated and dynamic,
resulting in fatigue damage to dental prostheses. Most fractures of dental restorations
are fatigue failure. The 4-point bend fatigue behavior of Co-Cr-Mo-W alloys manufactured
by investment casting (CAST) and selective laser melting (SLM) has received little
attention.
Purpose
The purpose of this in vitro study was to evaluate the 4-point bend fatigue property
of dental Co-Cr alloys and determine the relationship between microstructure and the
4-point bend fatigue property of Co-Cr alloys created by traditional casting and SLM.
These can guide the use of Co-Cr alloy in dentistry.
Material and methods
Co-Cr-Mo-W alloys were fabricated with a dimension of 45×2×2 mm by investment casting
and SLM. The 3-point bend test measured the ultimate bend strength with 3 specimens
in each group. The 4-point bend fatigue test evaluated the fatigue life under various
stresses, with 6 specimens in each group. The specimens were mechanically ground,
polished, and electrochemically etched. Scanning electron microscopy was used to identify
the microstructures of both etched specimens and fracture surfaces. X-ray diffraction
investigations were used to determine the phases. Significant differences in the bend
strength were analyzed by using the independent samples t test (α=.05), and the fatigue test was analyzed with ANCOVA (α=.05).
Results
The mean ±standard deviation bend strength of SLM specimens was 1837 ±3 MPa, higher
than the 1200 ±6 MPa for CAST specimens (P<.05). The maximum bend stress of the SLM specimens without fatigue failure was 735
MPa, which was statistically higher than the 394 MPa for CAST specimens (P<.05). The microstructure characteristics of the SLM alloy contributed to its excellent
fatigue performance. In SLM alloy, the γ phase constituted the majority with some
ε and Laves phases, while the cast alloy possessed higher ε and Laves phases. The
grains of SLM alloy were equiaxed and fine, and the second phases were fine and dispersive.
In contrast, the cast alloy possessed clear dendrites, and the second phases were
sizable.
Conclusions
The SLM dental Co-Cr-Mo-W alloy had statistically better 4-point bend fatigue properties
than cast alloy, which was associated with an improved microstructure.
To read this article in full you will need to make a payment
Purchase one-time access:
Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online accessOne-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:
Subscribe to Journal of Prosthetic DentistryAlready a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
References
- Effects of thermal treatments on microstructure and mechanical properties of a Co–Cr–Mo–W biomedical alloy produced by laser sintering.J Mech Behav Biomed. 2016; 60: 106-117
- Structural characterization of biomedical Co–Cr–Mo components produced by direct metal laser sintering.Mater Sci Eng C. 2015; 48: 263-269
- Selective laser melting dental CoCr alloy: microstructure, mechanical properties and corrosion resistance.Rapid Prototyp J. 2021; 27: 1457-1466
- The influence of cooling conditions on grain size, secondary phase precipitates and mechanical properties of biomedical alloy specimens produced by investment casting.J Mech Behav Biomed. 2013; 24: 53-63
- Defects-tolerant Co-Cr-Mo dental alloys prepared by selective laser melting.Dent Mater. 2015; 31: 1435-1444
- Effect of solution heat treatment on microstructure and mechanical properties of laser powder bed fusion produced cobalt-28chromium-6molybdenum.Mater Sci Eng A. 2020; 769: 138511
- Heat treatment of cast Co-Cr-Mo for orthopaedic implant use.J Mater Sci. 1983; 18: 391-401
- Grain growth during selective laser melting of a Co–Cr–Mo alloy.J Mater Sci. 2017; 52: 7415-7427
- Precipitation path of secondary phases during solidification of the Co-25.5%Cr-5.5%Mo-0.26%C alloy.Scr Mater. 2002; 47: 811-816
- Constrained dendritic growth and solute concentration effects in rapidly solidified Co-Cr alloys.Metall Mater Trans A Phys Metall Mater Sci. 2019; 50: 2272-2278
- Microstructural characterization of as-cast biocompatible Co–Cr–Mo alloys.Mater Charact. 2011; 62: 53-61
- Two-body wear of CoCr fabricated by selective laser melting compared with different dental alloys.Tribol Lett. 2015; 60: 25
- Additive manufacturing of biomedical constructs with biomimetic structural organizations.Materials. 2016; 9: 909
- Selective laser melting of Co-29Cr-6Mo alloy with laser power 180–360 W: cellular growth, intercellular spacing and the related thermal condition.Mater Charact. 2018; 135: 183-191
- Morphology and properties of CoCrMo parts fabricated by selective laser melting.Mater Sci Eng A. 2018; 713: 206-213
- Mechanical properties and microstructure of removable partial denture clasps manufactured using selective laser melting.Addit Manuf. 2015; 8: 117-123
- CoCr alloy processed by selective laser melting (SLM): effect of laser energy density on microstructure, surface morphology, and hardness.J Manuf Process. 2020; 52: 106-119
- Effect of selective laser melting process parameters on microstructure and properties of Co-Cr alloy.Materials. 2018; 11: 1546
- Effect of heat-treatment temperature on microstructures and mechanical properties of Co–Cr–Mo alloys fabricated by selective laser melting.Mater Sci Eng A. 2018; 726: 21-31
- 3D printing of aluminium alloys: additive manufacturing of aluminium alloys using selective laser melting.Prog Mater Sci. 2019; 106: 100578
- Formation of metastable cellular microstructures in selective laser melted alloys.J Alloy Compd. 2017; 707: 27-34
- Enhanced mechanical properties of as-forged Co-Cr-Mo-N alloys with ultrafine-grained structures.Metall Mater Trans A Phys Metall Mater Sci. 2012; 43: 5243-5257
- Evaluation of the mechanical properties and porcelain bond strength of cobalt-chromium dental alloy fabricated by selective laser melting.J Prosthet Dent. 2014; 111: 51-55
- Comparative analysis of the microstructures and mechanical properties of Co-Cr dental alloys fabricated by different methods.J Prosthet Dent. 2018; 120: 617-623
- Mechanical properties and metal-ceramic bond strength of Co-Cr alloy manufactured by selective laser melting.Materials. 2020; 13: 5745
- Effect of loading angles and implant lengths on the static and fatigue fractures of dental implants.Materials. 2021; 14: 5542
- Fatigue of dental ceramics.J Dent. 2013; 41: 1135-1147
- Essential structure of S-N curve: prediction of fatigue life and fatigue limit of defective materials and nature of scatter.Int J Fatigue. 2021; 146: 106138
- Effect of heat treatment on fatigue behavior of as-built notched Co-Cr-Mo parts produced by selective laser melting.Int J Fatigue. 2021; 142: 105926
- Fatigue strength of Co–Cr–Mo alloy clasps prepared by selective laser melting.J Mech Behav Biomed. 2016; 59: 446-458
Article info
Publication history
Published online: June 30, 2022
Footnotes
Supported by the Chengdu Major Science and Technology Innovation Project: Research and Application of 3D Printing (SLM) Co-Cr-Mo Powder for Denture Processing (2019-YF08-00221-GX-LH).
Identification
Copyright
© 2022 by the Editorial Council for the Journal of Prosthetic Dentistry.
