Effects of Additive Manufacturing Techniques for Cobalt-Chromium Alloys on Opposing Enamel Wear

Abstract

Objectives This study aimed to examine the wear on opposing enamel caused by additive manufacturing techniques for cobalt-chromium (Co-Cr) alloys. Selective laser melting (SLM) techniques were compared with conventional methods. Cast nickel-chromium (Ni-Cr) alloys were also included for comparison.

Materials and Methods Four groups of dental alloys were examined (n = 10/group): as-built SLM Co-Cr (CS), heat-treated SLM Co-Cr (CS-H), cast Co-Cr (CC), and cast Ni-Cr (NC) alloys. Surface roughness and hardness of these alloys were initially assessed. Wear test was conducted against human enamel cusps using a chewing simulator (49-N load, 1.6-Hz frequency). Volumetric and vertical enamel wear were measured at 60,000, 120,000, and 240,000 chewing cycles using an intraoral scanner combined with open-source 3D software.

Statistical Analysis Enamel wear was analyzed using a generalized estimating equation (α = 0.05).

Results Alloy hardness varied among the groups. NC exhibited the lowest hardness, followed by CS, CC, and CS-H. Throughout the entire test, no significant differences in enamel wear were observed among CS, CS-H, and CC. However, NC caused lower enamel wear than the other groups, with a more pronounced difference observed after 120,000 chewing cycles.

Conclusion SLM is a promising alternative for manufacturing Co-Cr alloys used in fixed dental prostheses, as it exhibited comparable enamel wear to conventional casting. Moreover, optimized heat treatment enhanced the hardness of SLM-fabricated alloys without increasing enamel wear. However, it is noteworthy that Co-Cr alloys fabricated by any techniques resulted in higher enamel wear than Ni-Cr alloys.

Keywords

casting technique - cobalt-chromium alloys - fixed indirect restoration - selective laser melting - tooth wear

Ethical Approval Statement

This study was approved by the Human Research Ethics Committee of the Faculty of Dentistry, Chulalongkorn University (HREC-DCU 2023–125).

Publikationsverlauf

Artikel online veröffentlicht:
01. Mai 2025

• References

• 1 Lambrechts P, Braem M, Vuylsteke-Wauters M, Vanherle G. Quantitative in vivo wear of human enamel. J Dent Res 1989; 68 (12) 1752-1754
• 2 Chun K, Choi H, Lee J. Comparison of mechanical property and role between enamel and dentin in the human teeth. J Dent Biomech 2014; 5: 1758736014520809
• 3 Dahl BL, Carlsson GE, Ekfeldt A. Occlusal wear of teeth and restorative materials. A review of classification, etiology, mechanisms of wear, and some aspects of restorative procedures. Acta Odontol Scand 1993; 51 (05) 299-311
• 4 Chun KJ, Lee JY. Comparative study of mechanical properties of dental restorative materials and dental hard tissues in compressive loads. J Dent Biomech 2014; 5: 1758736014555246
• 5 Hudson JD, Goldstein GR, Georgescu M. Enamel wear caused by three different restorative materials. J Prosthet Dent 1995; 74 (06) 647-654
• 6 Mahalick JA, Knap FJ, Weiter EJ. Occusal wear in prosthodontics. J Am Dent Assoc 1971; 82 (01) 154-159
• 7 Rosenstiel SF, Land MF, Fujimoto J. Contemporary Fixed Prosthodontics. 4th ed.. St. Louis, MO: Mosby; 2006: 258-285
• 8 Jacobi R, Shillingburg Jr HT, Duncanson Jr MG. A comparison of the abrasiveness of six ceramic surfaces and gold. J Prosthet Dent 1991; 66 (03) 303-309
• 9 Monasky GE, Taylor DF. Studies on the wear of porcelain, enamel, and gold. J Prosthet Dent 1971; 25 (03) 299-306
• 10 Wataha JC. Alloys for prosthodontic restorations. J Prosthet Dent 2002; 87 (04) 351-363
• 11 Reclaru L, Unger RE, Kirkpatrick CJ. et al. Ni-Cr based dental alloys; Ni release, corrosion and biological evaluation. Mater Sci Eng C Mater Biol Appl 2012; 32 (06) 1452-1460
• 12 Al Jabbari YS. Physico-mechanical properties and prosthodontic applications of Co-Cr dental alloys: a review of the literature. J Adv Prosthodont 2014; 6 (02) 138-145
• 13 van Noort R. The future of dental devices is digital. Dent Mater 2012; 28 (01) 3-12
• 14 Koutsoukis T, Zinelis S, Eliades G, Al-Wazzan K, Rifaiy MA, Al Jabbari YS. 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 (04) 303-312
• 15 Han X, Sawada T, Schille C. et al. Comparative analysis of mechanical properties and metal-ceramic bond strength of Co-Cr dental alloy fabricated by different manufacturing processes. Materials (Basel) 2018; 11 (10) 1801
• 16 Zhou Y, Li N, Yan J, Zeng Q. Comparative analysis of the microstructures and mechanical properties of Co-Cr dental alloys fabricated by different methods. J Prosthet Dent 2018; 120 (04) 617-623
• 17 Kassapidou M, Stenport VF, Johansson CB. et al. Cobalt chromium alloys in fixed prosthodontics: investigations of mechanical properties and microstructure. J Prosthet Dent 2023; 130 (02) 255.e1-255.e10
• 18 Ko K-H, Kang H-G, Huh Y-H, Park C-J, Cho L-R. Effects of heat treatment on the microstructure, residual stress, and mechanical properties of Co-Cr alloy fabricated by selective laser melting. J Mech Behav Biomed Mater 2022; 126: 105051
• 19 Kajima Y, Takaichi A, Kittikundecha N. et al. Effect of heat-treatment temperature on microstructures and mechanical properties of Co–Cr–Mo alloys fabricated by selective laser melting. Mater Sci Eng A Struct Mater 2018; 726: 21-31
• 20 Li H, Wang M, Lou D, Xia W, Fang X. Microstructural features of biomedical cobalt–chromium–molybdenum (CoCrMo) alloy from powder bed fusion to aging heat treatment. J Mater Sci Technol 2020; 45: 146-156
• 21 Fu W, Liu S, Jiao J. et al. Wear resistance and biocompatibility of Co-Cr dental alloys fabricated with cast and SLM techniques. Materials (Basel) 2022; 15 (09) 3263
• 22 Schwindling FS, Seubert M, Rues S. et al. Two-body wear of CoCr fabricated by selective laser melting compared with different dental alloys. Tribol Lett 2015; 60 (02) 25
• 23 Ramezani M, Ripin ZM. Investigation of wear and friction behavior of cobalt-chromium-molybdenum alloy produced by laser powder bed fusion. Appl Sci (Basel) 2023; 13 (19) 10582
• 24 Tonelli L, Ahmed MMZ, Ceschini L. A novel heat treatment of the additively manufactured Co28Cr6Mo biomedical alloy and its effects on hardness, microstructure and sliding wear behavior. Prog Addit Manuf 2023; 8 (02) 313-329
• 25 Jung YS, Lee JW, Choi YJ, Ahn JS, Shin SW, Huh JB. A study on the in-vitro wear of the natural tooth structure by opposing zirconia or dental porcelain. J Adv Prosthodont 2010; 2 (03) 111-115
• 26 Oh WS, Delong R, Anusavice KJ. Factors affecting enamel and ceramic wear: a literature review. J Prosthet Dent 2002; 87 (04) 451-459
• 27 Branco AC, Colaço R, Figueiredo-Pina CG, Serro AP. A state-of-the-art review on the wear of the occlusal surfaces of natural teeth and prosthetic crowns. Materials (Basel) 2020; 13 (16) 3525
• 28 Wang L, Liu Y, Si W. et al. Friction and wear behaviors of dental ceramics against natural tooth enamel. J Eur Ceram Soc 2012; 32 (11) 2599-2606
• 29 Archard JF. Contact and rubbing of flat surfaces. J Appl Phys 1953; 24: 981-988
• 30 Kim S-H, Kim Y-S. Effect of ductility on dry sliding wear of medium carbon steel under low load conditions. Met Mater Int 1999; 5 (03) 267-271
• 31 Rahaman ML, Zhang L, Liu M, Liu W. Surface roughness effect on the friction and wear of bulk metallic glasses. Wear 2015; 332: 1231-1237
• 32 Penfornis C, Jourani A, Mazeran P-E. Effect of grain sizes on the friction and wear behavior of dual-phase microstructures with similar macrohardness and composition. Coatings 2023; 13 (03) 533
• 33 Trevisiol C, Jourani A, Bouvier S. Effect of microstructures with the same chemical composition and similar hardness levels on tribological behavior of a low alloy steel. Tribol Int 2018; 127: 389-403
• 34 Zambrano OA, Gómez JA, Coronado JJ, Rodríguez SA. The sliding wear behaviour of steels with the same hardness. Wear 2019; 418: 201-207
• 35 Choi Y-J, Koak J-Y, Heo S-J. et al. Comparison of the mechanical properties and microstructures of fractured surface for Co-Cr alloy fabricated by conventional cast, 3-D printing laser-sintered and CAD/CAM milled techniques. J Korean Acad Prosthodont 2014; 52 (02) 67-73
• 36 Tonelli L, Fortunato A, Ceschini L. 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
• 37 Yan A, Atif AM, Wang X, Lan T, Wang Z. The microstructure and cracking behaviors of pure molybdenum fabricated by selective laser melting. Materials (Basel) 2022; 15 (18) 6230
• 38 Khorasani A, Gibson I, Awan US, Ghaderi A. The effect of SLM process parameters on density, hardness, tensile strength and surface quality of Ti-6Al-4V. Addit Manuf 2019; 25: 176-186