Journal of Prosthetic Dentistry

Chemical composition, surface roughness, and ceramic bond strength of additively manufactured cobalt-chromium dental alloys


      Statement of problem

      Selective laser melting (SLM) additive manufacturing (AM) technology is a current option to fabricate cobalt-chromium (Co-Cr) metal frameworks for dental prostheses. However, the Co-Cr alloy composition, surface roughness, and ceramic bond strength values that SLM metals can obtain are not well-defined.


      The purpose of this in vitro study was to compare the chemical composition, surface roughness, and ceramic shear bond strength of the milled and SLM Co-Cr dental alloys.

      Material and methods

      A total of 50 disks of 5 mm in diameter and 1 mm in thickness were fabricated by using subtractive (control group) and AM with each of following SLM providers: SLM-1 (EOS), SLM-2 (3D systems), and SLM-3 (Concept Laser). The milled disks were airborne-particle abraded with 100-μm aluminum oxide particles. All the specimens were cleaned before surface roughness (Ra), weight (Wt%), and atomic (At%) percentages were analyzed. Three-dimensional profilometry was used to analyze the topographical properties of the surface parameters Ra (mean surface roughness). The chemical composition of Co-Cr alloy specimens was determined by using energy dispersive X-ray (EDAX) elemental analysis in a scanning electron microscope (SEM). Thereafter, the specimens were bonded to a ceramic (Dentine A3 and Enamel S-59; Creation CC) interface. Specimens were stored for 24 hours at 23 °C. The bond strength of the SLM-ceramic interface was measured by using the macroshear test (SBT) method (n=10). Adhesion tests were performed in a universal testing machine (1 mm/min). The Shapiro-Wilk test revealed that the chemical composition data were not normally distributed. Therefore, the atomic (At%) and weight percentages (Wt%) were analyzed by using the Kruskal-Wallis test, followed by pairwise Mann-Whitney U tests between the control and AM groups (AM-1 to AM-4). However, the Shapiro-Wilk test revealed that the surface roughness (Ra) and ceramic bond strength data were normally distributed. Therefore, data were analyzed by using 1-way ANOVA, followed by the post hoc Sidak test (α=.05).


      Significant differences were obtained in Wt%, At%, and Ra values among the Co-Cr alloys evaluated (P<.05). Furthermore, the control group revealed significantly lower mean ±standard deviation Ra values (0.79 ±0.11 μm), followed by AM-3 (1.57 ±0.15 μm), AM-2 (1.80 ±0.43 μm), AM-1 (2.43 ±0.34 μm), and AM-4 (2.84 ±0.27 μm). However, no significant differences were obtained in the metal-ceramic shear bond strength among the different groups evaluated, ranging from mean ±standard deviation 75.77 ±11.92 MPa to 83.65 ±12.21 MPa.


      Co-Cr dental alloys demonstrated a significant difference in their chemical compositions. Subtractive and additive manufacturing procedures demonstrated a significant influence on the surface roughness of the Co-Cr alloy specimens. However, the metal-ceramic shear bond strength of Co-Cr alloys was found to be independent of the manufacturing process.
      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 access
      One-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 to Journal of Prosthetic Dentistry
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Anusavice K.J.
        • Hojjatie B.
        • Dehoff P.H.
        Influence of metal thickness on stress distribution in metal-ceramic crowns.
        J Dent Res. 1986; 09: 1173-1178
        • Scurria M.S.
        • Bader J.M.
        • Shugars D.A.
        Meta-analysis of fixed partial denture survival: prostheses and abutments.
        J Prosthet Dent. 1998; 79: 459-464
        • Tan K.
        • Pjetursson B.E.
        • Lang N.P.
        • Chan E.S.Y.
        A systematic review of the survival and complication rates of fixed dental dentures (FDP) after an observation period of at least 5 years. III. Conventional FDPs.
        Clin Oral Implants Res. 2004; 15: 654-666
        • Pjetursson B.E.
        A systematic review of the survival and complication rates of all-ceramic and metal–ceramic reconstructions after an observation period of at least 3 years. Part I: single crowns.
        Clin Oral Implants Res. 2008; 3: 326-328
        • Brägger U.
        • Hirt-Steiner S.
        • Schnell N.
        • Schmidlin K.
        • Salvi G.E.
        • Pjetursson B.
        • et al.
        Complications and failures rates of fixed dental prostheses on patients treated for periodontal disease.
        Clin Oral Implants Res. 2011; 22: 70-77
        • Naylor W.P.
        Introduction to metal-ceramic technology.
        Quintessence, Chicago, IL1992: 28-38
        • Roberts H.W.
        • Berzins D.W.
        • Moore B.K.
        • Charlton D.G.
        Metal-ceramic alloys in dentistry: a review.
        J Prosthodont. 2009; 18: 188-194
        • Wataha J.C.
        • Messer R.L.
        Casting alloys.
        Dent Clin North Am. 2004; 48: 499-512
        • Singh V.
        Rapid prototyping, materials for RP and applications of RP.
        Int J Eng Res Sci. 2013; 4: 473-480
        • Witkowski S.
        CAD/CAM in dental technology.
        Quintessence Dent Technol. 2005; 28: 169-184
        • Vandenbroucke B.
        • Kruth J.P.
        Selective Laser Melting of biocompatible metals for rapid manufacturing of medical parts.
        Rapid Prototyp J. 2007; 13: 196-203
        • Horn T.J.
        • Harrysson O.L.A.
        Overview of current additive manufacturing technologies and selected applications.
        Sci Prog. 2012; 95: 255-282
        • Revilla-León M.
        • Özcan M.
        Additive manufacturing technologies used for 3D metal printing in dentistry.
        Curr Oral Health Rep. 2017; 4: 201-208
        • ASTM
        • Committee F42 on Additive Manufacturing Technologies, ISO/ASTM 52900:2015 (ASTM F2792). Additive manufacturing - general principles and terminology
        (Available at:) (Accessed August 1, 2019)
        • Abd-Elghany K.
        • Bourrell D.L.
        Property evaluation of 304 stainless steel fabricated by selective laser melting.
        Rapid Prototyp J. 2012; 18: 420-428
        • Goodridge R.D.
        • Tuck C.J.
        • Hague R.J.
        Laser sintering of polyamides and other polymers.
        Prog Mater Sci. 2012; 57: 229-267
        • Deckard C.
        • Beaman J.
        Process and control issues in selective laser sintering.
        ASME Prod Eng Div. 1988; 33: 191-197
        • Deckard C.R.
        Patent US 4863538-A. Method and apparatus for producing parts by selective sintering.
        • Kim K.B.
        • Kim J.H.
        • Kim W.C.
        • Kim J.H.
        Three-dimensional evaluation of gaps associated with fixed dental prostheses fabricated with new technologies.
        J Prosthet Dent. 2014; 112: 1432-1436
        • Murr L.E.
        • Martinez E.
        • Gaytan S.M.
        • Ramirez D.A.
        • Machado B.I.
        • Shindo P.W.
        • et al.
        Microstructural architecture, microstructures, and mechanical properties for a nickel-base superalloy fabricated by electron beam melting.
        Metal Mater Trans A. 2011; 42: 3491
        • Yadroitsev I.
        • Krakhmalev P.
        • Yadroitsava I.
        • Johansson S.
        • Smurov I.
        Energy input effect on morphology and microstructure of selective laser melting single track from metallic powder.
        J Mater Process Technol. 2013; 213: 606-613
        • Frazier W.E.
        Metal additive manufacturing: a review.
        J Mater Eng Perform. 2014; 23: 1917-1928
        • Örtop A.
        • Jönsson D.
        • Mouhsen A.
        • Vult Von Steyern P.
        The fit of cobalt-chromium three-unit fixed dental prostheses fabricated with four different techniques: a comparative in vitro study.
        Dent Mater. 2011; 27: 356-363
        • Tamac E.
        • Toksavul S.
        • Toman M.
        Clinical marginal and internal adaptation of CAD/CAM milling, laser sintering and cast metal ceramic crowns.
        J Prosthet Dent. 2014; 112: 909-913
        • Suleiman S.H.
        • VultvonSteyern P.
        Fracture strength of porcelain fused to metal crowns made of cast, milled or laser-sintered cobalt-chromium.
        Acta Odontol Scand. 2013; 71: 1280-1289
        • Osakada K.
        • Shiomi M.
        Flexible manufacturing of metallic products by selective laser melting of powder.
        Int J Machine Tools Manuf. 2006; 46: 1188-1193
        • Murr L.E.
        • Gaytan S.M.
        • Ramirez D.A.
        • Martinez E.
        • Hernandez J.
        • Amato K.N.
        • et al.
        Metal fabrication by additive manufacturing using laser and electron beam melting technologies.
        J Mater Sci Technol. 2012; 28: 1-14
        • Quian B.
        • Saeidi K.
        • Kvetková L.
        • Lofaj F.
        • Xiao C.
        • Shen Z.
        Defects-tolerant Cr-Co-Mo dental alloys prepared by selective laser melting.
        Dent Mater. 2015; 31: 1435-1444
        • Petrovic V.
        • Haro J.V.
        • Blasco J.R.
        • Portolés L.
        Additive manufacturing solutions for improved medical implants.
        in: Biomedicine. 2012: 150-159 (Available at:) (Accessed August 1, 2019)
        • Koutsoukis T.
        • Zinelis S.
        • Eliades G.
        • Al-Wazzan K.
        • Al Rifaiy M.
        • Al Jabbari Y.S.
        Selective Laser Melting technique of Cr-Co dental alloys: a review of structure and properties and comparative analysis with other available techniques.
        J Prosthodont. 2015; 24: 303-312
        • Takaichi A.
        • Suyalatu
        • Nakamoto T.
        • Joko N.
        • Nomura N.
        • Tsutsumi Y.
        • et al.
        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
        • Malhotra M.L.
        • Maickel L.B.
        Shear bond strength in porcelain- metal restorations.
        J Prosthet Dent. 1980; 43: 397-400
        • Drummond J.L.
        • Randolph R.G.
        • Jekkals V.J.
        • Lenke J.W.
        Shear testing of the porcelain metal bond.
        J Dent Res. 1984; 44: 1400-1401
        • Van Noort R.
        • Noroozi S.
        • Howard I.C.
        • Cardew G.
        A critique of bond strength measurements.
        J Dent. 1989; 17: 61-67
        • Dundar M.
        • Özcan M.
        • Gokce B.
        • Comlekoglu E.
        • Leite F.
        • Valandro L.F.
        Comparison of two bond strength testing methodologies for bilayered all-ceramics.
        Dent Mater. 2007; 23: 630-636
        • Valandro L.F.
        • Özcan M.
        • Amaral R.
        • Vanderlei A.
        • Bottino M.A.
        Effect of testing methods on the bond strength of resin to zirconia-alumina ceramic: microtensile versus shear test.
        Dent Mater J. 2008; 27: 849-855
        • Serra-Prat J.
        • Cano-Batalla J.
        • Cabratosa-Termes J.
        • Figueras-Àlvarez O.
        Adhesion of dental porcelain to cast, milled, and laser-sintered cobalt-chromium alloys: shear bond strength and sensitivity to thermocycling.
        J Prosthet Dent. 2014; 112: 600-605
        • Juntavee N.
        • Oeng S.E.
        Shear bond strength of ceramic fused to CAD-CAM milled alloys.
        J Clin Exp Dent. 2018; 10: e32-e40
        • De Melo R.M.
        • Travassos A.C.
        • Neisser M.P.
        Shear bond strength of a ceramic system to alternative metal alloys.
        J Prosthet Dent. 2005; 93: 64-69
        • Akova T.
        • Ucar Y.
        • Tukay A.
        • Balkaya M.C.
        • Brantley W.A.
        Comparison of the bond strength of laser-sintered and cast base metal dental alloys to porcelain.
        Dent Mater. 2008; 24: 1400-1404
        • Wang H.
        • Feng Q.
        • Li N.
        • Xu S.
        Evaluation of metal-ceramic bond characteristics of three dental Co-Cr alloys prepared with different fabrication techniques.
        J Prosthet Dent. 2016; 116: 916-923
        • Li J.
        • Chen C.
        • Liao J.
        • Liu L.
        • Ye X.
        • Lin S.
        • et al.
        Bond strengths of porcelain to cobalt-chromium alloys made by casting, milling, and selective laser melting.
        J Prosthet Dent. 2017; 118: 69-75
        • Kaleli N.
        • Saraç D.
        Comparison of porcelain bond strength of different metal frameworks prepared by using conventional and recently introduced fabrication methods.
        J Prosthet Dent. 2017; 118: 76-82
        • Lawaf S.
        • Nasermostofi S.
        • Afradeh M.
        • Azizi A.
        Comparison of the bond strength of ceramics to Co-Cr alloys made by casting and selective laser melting.
        J Adv Prosthodont. 2017; 9: 52-56
        • Ekren O.
        • Ozkomur A.
        • Ucar Y.
        Effect of layered manufacturing techniques, alloy powders, and layer thickness on metal-ceramic bond strength.
        J Prosthet Dent. 2018; 119: 481-487
        • Park W.U.
        • Park H.G.
        • Hwang K.H.
        • Zhao J.
        • Lee J.K.
        Interfacial property of dental cobalt-chromium alloys and their bonding strength with porcelains.
        J Nanosci Nanotechnol. 2017; 17: 2585-2588
        • Al Jabbari Y.S.
        • Koutsoukis T.
        • Barmpagadaki X.
        • Zinelis S.
        Metallurgical and interfacial characterization of PFM Co-Cr dental alloys fabricated via casting, milling, or selective laser melting.
        Dent Mater. 2014; 30: e79-e88
        • Taini T.
        • Mangano C.
        • Sammons R.L.
        • Mangano F.
        • Macchi A.
        • Piattelli A.
        Direct laser metal sintering as a new approach to fabrication of an isoelastic functionally graded material for manufacture of porous titanium dental implants.
        Dent Mater. 2008; 24: 1525
        • Özcan M.
        • Niedermeier W.
        Clinical study on the reasons for and location of failures of metal-ceramic restorations and survival of repairs.
        Int J Prosthodont. 2002; 15: 299-302