Abstract
Statement of problem
Selective laser melting (SLM) Ti-6Al-4V has been used for removable partial dentures,
but the impact of SLM Ti-6Al-4V build orientation is not evident.
Purpose
The purpose of this in vitro study was to investigate the microstructure and properties
of SLM Ti-6Al-4V clasps with different build orientations compared with cast Ti-6Al-4V
clasps.
Material and methods
Forty-eight clasps were made from Ti-6Al-4V alloys—by SLM with 3 different build orientations
(SLM0, SLM45, and SLM90) and cast (CAST) as a control. The microstructure was investigated
by using a metallographic microscope and a confocal laser scanning microscope. The
fit and surface roughness of the clasps were measured, and the physical properties
were evaluated. In addition, the von Mises stresses in the clasps were calculated
by finite element analysis. All specimens were then subjected to insertion and removal
tests in artificial saliva to model 5 years of clinical use. After these tests, 3-point
bend tests were used to analyze the fracture surface of the clasp arms, which were
observed by using a scanning electron microscope. All data were statistically analyzed
(α=.05).
Results
The microstructure of the Ti-6Al-4V specimens was a comixture of α+β phases. In addition,
growth directions of β grains were approximately parallel to the build orientation,
with acicular α grains present between β grains. SLM0 and SLM45 had significantly
higher roughness than SLM90. Even though the fit was inferior to that of SLM90, SLM0
and SLM45 still performed better than cast specimens (P<.05). The finite element analysis showed that the maximum von Mises stress was located
on the middle part of the retainer arms and that the values of the 0.50-mm undercut
clasps were much lower than the elastic limit. In addition, the decrease of retentive
force in SLM90 clasps was less than that of the CAST group (P<.05). CAST clasps showed brittle fracture, whereas all SLM clasps showed ductile
fracture.
Conclusions
The microstructure of SLM Ti-6Al-4V affected the properties of clasps by changing
the anisotropy of specimens. Among the tested groups, SLM90 clasps had the best fit,
the lowest surface roughness, and the best fatigue resistance. Furthermore, SLM Ti-6Al-4V
clasps could be engaged into 0.50-mm undercuts.
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
- Removable partial dentures: use of rapid prototyping.J Prosthodont. 2014; 23: 588-591
- Fatigue strength of Co-Cr-Mo alloy clasps prepared by selective laser melting.J Mech Behav Biomed Mater. 2016; 59: 446-458
- Finite element analysis on preferable I-bar clasp shape.J Oral Rehabil. 2001; 28: 413-417
- Clinical performance of cast clasp-retained removable partial dentures: a retrospective study.Int J Prosthodont. 2012; 25: 138-144
- Finite element stress analysis and fatigue behavior of cast circumferential clasps.J Prosthet Dent. 2007; 97: 39-44
- Fabrication of titanium alloy frameworks for complete dentures by selective laser melting.J Prosthet Dent. 2014; 112: 1441-1447
- An overview of treatment considerations for esthetic restorations: a review of the literature.J Prosthet Dent. 2006; 96: 433-442
- Present status of titanium removable dentures--a review of the literature.J Oral Rehabil. 2008; 35: 706-714
- Selective laser melting technique of Co-Cr dental alloys: a review of structure and properties and comparative analysis with other available techniques.J Prosthodont. 2015; 24: 303-312
- Selective laser sintering in biomedical engineering.Med Biol Eng Comput. 2013; 51: 245-256
- Rapid prototyping--when virtual meets reality.Int J Comput Dent. 2014; 17: 297-306
- Removable partial denture alloys processed by laser-sintering technique.J Biomed Mater Res B Appl Biomater. 2017; 106: 1174-1185
- The influence of various cooling rates during laser alloying on nodular iron surface layer.Opt Laser Technol. 2018; 102: 60-67
- Coupling effects of melt treatment and ultrasonic treatment on solidifying microstructure and mechanical performance of Ti44Al6Nb1Cr alloy.Metall Mater Trans A. 2018; 49A: 537-549
- Surface characteristics and corrosion properties of selective laser melted Co-Cr dental alloy after porcelain firing.Dent Mater. 2014; 30: 263-270
- In vitro biocompatibility of CoCrMo dental alloys fabricated by selective laser melting.Dent Mater. 2014; 30: 525-534
- Microstructures and mechanical properties of Co-29Cr-6Mo alloy fabricated by selective laser melting process for dental applications.J Mech Behav Biomed Mater. 2013; 21: 67-76
- Effect of the build orientation on the mechanical properties and fracture modes of SLM Ti–6Al–4V.J Mate Sci Eng A. 2014; 616: 1-11
- Effect of molten pool boundaries on the mechanical properties of selective laser melting parts.J Mater Process Tech. 2014; 214: 2660-2667
- Fatigue resistance and retentive force of cast clasps treated by shot peening.J Prosthodont Res. 2013; 57: 186-194
- Corrosion-fatigue of laser-repaired commercially pure titanium and Ti-6Al-4V alloy under different test environments.J Oral Rehabil. 2004; 31: 1029-1034
- Cyclic fatigue properties of cobalt-chromium alloy clasps for partial removable dental prostheses.J Prosthet Dent. 2010; 104: 389-396
- Fatigue of Ti6Al4V structural health monitoring systems produced by selective laser melting.Materials (Basel). 2016; 9: 106-111
- Ductility improvement due to martensite α′ decomposition in porous Ti–6Al–4V parts produced by selective laser melting for orthopedic implants.J Mech Behav Biomed Mater. 2016; 54: 149-158
- 3D roughness profile model in fused deposition modelling.Rapid Prototyping J. 2013; 19: 240-252
- Surface roughness analysis, modelling and prediction in selective laser melting.J Mater Process Tech. 2013; 213: 589-597
- Modelling micro geometrical profiles in fused deposition process.Int J Adv Manuf Tech. 2012; 61: 945-956
- Microstructure and tensile properties of iron parts fabricated by selective laser melting.Opt Laser Technol. 2014; 56: 451-460
- Fracture mechanisms in high-cycle fatigue of selective laser melted Ti-6Al-4V.Key Eng Mater. 2015; 627: 125-128
- Effects of solution treatment and aging on the microstructure, mechanical properties, and corrosion resistance of a beta type Ti-Ta-Hf-Zr alloy.RSC Adv. 2017; 7: 12309-12317
Article info
Publication history
Published online: April 12, 2019
Footnotes
ZED Dental Co, Ltd. provided study material.
Identification
Copyright
© 2019 by the Editorial Council for The Journal of Prosthetic Dentistry.
