Journal of Prosthetic Dentistry

The effect of layer thickness on the porcelain bond strength of laser-sintered metal frameworks

Published:February 16, 2019DOI:


      Statement of problem

      Laser sintering has become a common manufacturing technique in the fabrication of metal-ceramic restorations. The layer thickness of the sintering process may affect the surface morphology and hence the porcelain bond strength. However, limited information is available on the effect of layer thickness on porcelain bond strength.


      The purpose of this in vitro study was to evaluate the porcelain bond strength of direct metal laser-melted (DMLM) cobalt-chromium (Co-Cr) metal frameworks sintered with 25-μm and 50-μm layer thicknesses.

      Material and methods

      Thirty metal frameworks (n=10) were fabricated by using the lost-wax technique (group C [control]), DMLM with a 25-μm layer thickness (group L25), and DMLM with a 50-μm layer thickness (group L50) according to the International Organization for Standardization (ISO) 9693-1. The surface roughness of 1 metal specimen from each group was analyzed by atomic force microscopy. After porcelain firing, a 3-point bend test was applied to each metal-ceramic specimen as in ISO 9693-1. In addition, 1 metal framework from each group was prepared and examined by scanning electron microscopy to evaluate surface morphology. Data were analyzed statistically by using 1-way analysis of variance and the Tukey honestly significant difference tests (α=.05).


      Group C and group L25 showed significantly higher (P<.001) mean porcelain bond strength values than group L50, and no significant bond strength difference was found between groups C and L25. All groups generally exhibited an adhesive type of failure.


      The results indicate that layer thickness may affect the porcelain bond strength of DMLM metal frameworks.
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        • Heintze S.D.
        • Rousson V.
        Survival of zirconia- and metal-supported fixed dental prostheses: a systematic review.
        Int J Prosthodont. 2010; 23: 493-502
        • Park J.K.
        • Kim H.Y.
        • Kim W.C.
        • Kim J.H.
        Evaluation of the fit of metal ceramic restorations fabricated with a pre-sintered soft alloy.
        J Prosthet Dent. 2016; 116: 909-915
        • Xiang N.
        • Xin X.Z.
        • Chen J.
        • Wei B.
        Metal-ceramic bond strength of Co-Cr alloy fabricated by selective laser melting.
        J Dent. 2012; 40: 453-457
        • Ozcan M.
        Fracture reasons in ceramic-fused-to-metal restorations.
        J Oral Rehabil. 2003; 30: 265-269
        • 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
        • International Organization for Standardization
        ISO 9693-1. Dentistry compability testing. Part 1: Metal-ceramic systems.
        International Organization for Standardization, Geneva2012 (ISO Store Order: OP-184149 (Date: 2017-06-09). Available at:)
        • Joias R.M.
        • Tango R.N.
        • Junho de Araujo J.E.
        • Junho de Araujo M.A.
        • Ferreira Anzaloni Saavedra Gde S.
        • Paes-Junior T.J.
        • et al.
        Shear bond strength of a ceramic to Co-Cr alloys.
        J Prosthet Dent. 2008; 99: 54-59
        • Lombardo G.H.
        • Nishioka R.S.
        • Souza R.O.
        • Michida S.M.
        • Kojima A.N.
        • Mesquita A.M.
        • et al.
        Influence of surface treatment on the shear bond strength of ceramics fused to cobalt-chromium.
        J Prosthodont. 2010; 19: 103-111
        • 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
        • Korkmaz T.
        • Asar V.
        Comparative evaluation of bond strength of various metal–ceramic restorations.
        Mater Des. 2009; 30: 445-451
        • Castillo-Oyague R.
        • Osorio R.
        • Osorio E.
        • Sanchez-Aguilera F.
        • Toledano M.
        The effect of surface treatments on the microroughness of laser-sintered and vacuum-cast base metal alloys for dental prosthetic frameworks.
        Microsc Res Tech. 2012; 75: 1206-1212
        • 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: 617-623
        • Önöral Ö.
        • Ulusoy M.
        • Seker E.
        • Etikan İ.
        Influence of repeated firings on marginal, axial, axio-occlusal, and occlusal fit of metal-ceramic restorations fabricated with different techniques.
        J Prosthet Dent. 2018; 120: 415-420
        • 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
        • 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
        • Serra-Prat J.
        • Cano-Batalla J.
        • Cabratosa-Termes J.
        • Figueras-Alvarez 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
        • Sun J.
        • Zhang F.Q.
        The application of rapid prototyping in prosthodontics.
        J Prosthodont. 2012; 21: 641-644
        • Strub J.R.
        • Rekow E.D.
        • Witkowski S.
        Computer-aided design and fabrication of dental restorations: current systems and future possibilities.
        J Am Dent Assoc. 2006; 137: 1289-1296
        • van Noort R.
        The future of dental devices is digital.
        Dent Mater. 2012; 28: 3-12
        • Kim E.H.
        • Lee D.H.
        • Kwon S.M.
        • Kwon T.Y.
        A microcomputed tomography evaluation of the marginal fit of cobalt-chromium alloy copings fabricated by new manufacturing techniques and alloy systems.
        J Prosthet Dent. 2017; 117: 393-399
        • Santos E.C.
        • Shiomi M.
        • Osakada K.
        • Laoui T.
        Rapid manufacturing of metal components by laser forming.
        Int J Mach Tool Manuf. 2006; 46: 1459-1468
        • Koutsoukis T.
        • Zinelis S.
        • Eliades G.
        • Al-Wazzan K.
        • Rifaiy M.A.
        • Al Jabbari Y.S.
        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
        • Mazzoli A.
        Selective laser sintering in biomedical engineering.
        Med Biol Eng Comput. 2013; 51: 245-256
        • Withers P.J.
        • Bhadeshia H.
        Residual stress. Part 2–Nature and origins.
        Mater Sci Technol. 2001; 17: 366-375
        • Mercelis P.
        • Kruth J.-P.
        Residual stresses in selective laser sintering and selective laser melting.
        Rapid Prototyp J. 2006; 12: 254-265
        • Schaub D.A.
        • Chu K.-R.
        • Montgomery D.C.
        Optimizing stereolithography throughput.
        J Manuf Syst. 1997; 16: 290-303
        • Chockalingam K.
        • Jawahar N.
        • Chandrasekhar U.
        Influence of layer thickness on mechanical properties in stereolithography.
        Rapid Prototyp J. 2006; 12: 106-113
        • Simchi A.
        Direct laser sintering of metal powders: Mechanism, kinetics and microstructural features.
        Mater Sci Eng. 2006; 428: 148-158
        • Sames W.J.
        • List F.
        • Pannala S.
        • Dehoff R.R.
        • Babu S.S.
        The metallurgy and processing science of metal additive manufacturing.
        Int Mater Rev. 2016; 61: 315-360
        • Bae E.J.
        • Kim J.H.
        • Kim W.C.
        • Kim H.Y.
        Bond and fracture strength of metal-ceramic restorations formed by selective laser sintering.
        J Adv Prosthodont. 2014; 6: 266-271
        • Gu D.
        • Shen Y.
        Balling phenomena in direct laser sintering of stainless steel powder: Metallurgical mechanisms and control methods.
        Mater Des. 2009; 30: 2903-2910
        • O'Brien W.J.
        Dental materials and their selection.
        4th ed. Quintessence Publishing, Hanover Park2008: 212-229
        • Della Bona A.
        • Van Noort R.
        Shear vs. tensile bond strength of resin composite bonded to ceramic.
        J Dent Res. 1995; 74: 1591-1596
        • Papazoglou E.
        • Brantley W.A.
        Porcelain adherence vs force to failure for palladium–gallium alloys: a critique of metal–ceramic bond testing.
        Dent Mater. 1998; 14: 112-119
        • Sadeq A.
        • Cai Z.
        • Woody R.D.
        • Miller A.W.
        Effects of interfacial variables on ceramic adherence to cast and machined commercially pure titanium.
        J Prosthet Dent. 2003; 90: 10-17
        • Lenz J.
        • Schwarz S.
        • Schwickerath H.
        • Sperner F.
        • Schäfer A.
        Bond strength of metal–ceramic systems in three-point flexure bond test.
        J Appl Biomater. 1995; 6: 55-64