Journal of Prosthetic Dentistry
Research and Education| Volume 126, ISSUE 6, P772-778, December 2021

Can ceramic veneer spark erosion and mechanical cycling affect the accuracy of milled complete-arch frameworks supported by 6 implants?


      Statement of problem

      Milling is a well-established method for manufacturing prosthetic frameworks. However, information about the influence of ceramic veneer and spark erosion on the accuracy of the all-on-six complete-arch fixed frameworks manufactured from different materials is lacking.


      The purpose of this in vitro study was to compare the accuracy of milled complete-arch fixed frameworks with zirconia, cobalt-chromium, and titanium at different steps of their manufacturing process and the influence of mechanical cycling.

      Material and methods

      Fifteen milled complete-arch fixed frameworks, supported by 6 implants, were made in zirconia, cobalt-chromium, and titanium (n=5). The fit was measured by the single-screw test protocol. Stress was measured by photoelastic analysis. The loosening torque was evaluated by tightening the screws, retightening them after 10 minutes, and then evaluating the loosening torque 24 hours later. Thereafter, all frameworks received ceramic veneer, and the previous tests were repeated. Cobalt-chromium and titanium frameworks received spark erosion after ceramic veneer, and all analyses were repeated. Before and after mechanical cycling, loosening torque was evaluated. The results were subjected to 2-way repeated-measures ANOVA and the Bonferroni test (α=.05).


      Titanium presented higher fit values than zirconia (P=.037) and similar to cobalt-chromium frameworks (P>.05) at baseline. After ceramic veneer, higher fit levels were observed for zirconia (P=.001) and cobalt-chromium (P=.008). Titanium showed higher stress values (P<.05) regardless of time. Baseline for all materials presented lower stress values (P<.05). Higher loosening torque values were found for the titanium group at baseline (P<.001) and after ceramic veneer (P<.001). Spark erosion improved fit and loosening torque values only for cobalt-chromium (P<.05). Mechanical cycling did not influence the loosening torque (P>.05).


      Titanium milled complete-arch fixed frameworks presented poorer fit values than zirconia, although the loosening torque at baseline was higher. Ceramic veneer increased the fit levels for zirconia and cobalt-chromium, decreased the loosening torque values for cobalt-chromium, and enhanced stress levels. Spark erosion can be a reliable technique to improve fit and loosening torque for cobalt-chromium frameworks. Mechanical cycling did not decrease loosening torque.
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        • Moraschini V.
        • Poubel L.A.D.C.
        • Ferreira V.F.
        • Barboza E.D.S.P.
        Evaluation of survival and success rates of dental implants reported in longitudinal studies with a follow-up period of at least 10 years: a systematic review.
        Int J Oral Maxillofac Surg. 2015; 44: 377-388
        • Chiapasco M.
        • Zaniboni M.
        Methods to treat the edentulous posterior maxilla: implants with sinus grafting.
        J Oral Maxillofac Surg. 2009; 67: 867-871
        • Agliardi E.L.
        • Pozzi A.
        • Stappert C.F.J.
        • Benzi R.
        • Romeo D.
        • Gherlone E.
        Immediate fixed rehabilitation of the edentulous maxilla: a prospective clinical and radiological study after 3 years of loading.
        Clin Implant Dent Relat Res. 2014; 16: 292-302
        • Almeida E.O.
        • Rocha E.P.
        • Freitas Júnior A.C.
        • Anchieta R.B.
        • Poveda R.
        • Gupta N.
        • et al.
        Tilted and short implants supporting fixed prosthesis in an atrophic maxilla: a 3D-FEA biomechanical evaluation.
        Clin Implant Dent Relat Res. 2015; 17: e332-e342
        • Maló P.
        • de Araújo Nobre M.
        • Rangert B.
        Short implants placed one-stage in maxillae and mandibles: a retrospective clinical study with 1 to 9 years of follow-up.
        Clin Implant Dent Relat Res. 2007; 9: 15-21
        • Bhering C.L.B.
        • Mesquita M.F.
        • Kemmoku D.T.
        • Noritomi P.Y.
        • Consani R.L.X.
        • Barão V.A.R.
        Comparison between all-on-four and all-on-six treatment concepts and framework material on stress distribution in atrophic maxilla: a prototyping guided 3D-FEA study.
        Mater Sci Eng C. 2016; 69: 715-725
        • Presotto A.G.C.
        • Bhering C.L.B.
        • Caldas R.A.
        • Consani R.L.X.
        • Barão V.A.R.
        • Mesquita M.F.
        Photoelastic and finite element stress analysis reliability for implant-supported system stress investigation.
        Braz J Oral Sci. 2018; 17: 1-13
        • Bhering C.L.B.
        • Takahashi J.M.F.K.
        • Luthi L.F.
        • Henriques G.E.P.
        • Consani R.L.X.
        • Mesquita M.F.
        Influence of the casting technique and dynamic loading on screw detorque and misfit of single unit implant-supported prostheses.
        Acta Odontol Scand. 2013; 71: 404-409
        • Farina A.P.
        • Spazzin A.O.
        • Pantoja J.M.
        • Consani R.L.
        • Mesquita M.F.
        An in vitro comparison of joint stability of implant-supported fixed prosthetic suprastructures retained with different prosthetic screws and levels of fit under masticatory simulation conditions.
        Int J Oral Maxillofac Implants. 2012; 27: 833-838
        • Bhering C.L.B.
        • Marques Ida S.V.
        • Takahashi J.M.F.K.
        • Barão V.A.R.
        • Consani R.L.X.
        • Mesquita M.F.
        Fit and stability of screw-retained implant-supported frameworks under masticatory simulation: influence of cylinder type.
        J Prosthodont. 2016; 25: 459-465
        • Nakaoka M.M.
        • Nuñez-Pantoja J.M.
        • Takahashi J.M.
        • Consani R.L.
        • Mesquita M.F.
        Misfit of pure titanium frameworks: effect of veneer coverage and spark erosion process.
        Acta Odontol Scand. 2011; 69: 238-242
        • Svanborg P.
        • Tech D.
        • Saarva N.
        • Tech D.
        • Stenport V.
        Fit of 3Y-TZP complete-arch implant-supported fixed dental prostheses before and after porcelain veneering.
        J Prosthet Dent. 2019; 122: 137-141
        • Abduo J.
        Fit of CAD/CAM implant frameworks: a comprehensive review.
        J Oral Implantol. 2014; 40: 758-766
        • Katsoulis J.
        • Mericske-Stern R.
        • Rotkina L.
        • Zbären C.
        • Enkling N.
        • Blatz M.B.
        Precision of fit of implant-supported screw-retained 10-unit computer-aided-designed and computer-aided-manufactured frameworks made from zirconium dioxide and titanium: an in vitro study.
        Clin Oral Implants Res. 2014; 25: 165-174
        • Presotto A.G.C.
        • Bhering C.L.B.
        • Mesquita M.F.
        • Barão V.A.R.
        Marginal fit and photoelastic stress analysis of CAD-CAM and overcast 3-unit implant-supported frameworks.
        J Prosthet Dent. 2017; 117: 373-379
        • Saito A.
        • Komine F.
        • Markus B.
        • Matsumura H.
        A comparison of bond strength of layered veneering porcelains to zirconia and metal.
        J Prosthet Dent. 2009; 104: 247-257
        • Spies B.C.
        • Fross A.
        • Adolfsson E.
        • Bagegni A.
        • Doerken S.
        • Kohal R.
        Stability and aging resistance of a zirconia oral implant using a carbon fiber-reinforced screw for implant-abutment connection.
        Dent Mater. 2018; 34: 1585-1595
        • Pieralli S.
        • Kohal R.
        • Rabel K.
        • Vach K.
        • Spies B.C.
        Clinical outcomes of partial and full- supported fixed dental prostheses. A systematic review and meta-analysis.
        Clin Oral Implants Res. 2018; 29: 224-236
        • Al-Meraikhi H.
        • Yilmaz B.
        • McGlumphy E.
        In vitro fit of CAD-CAM complete arch screw-retained titanium and zirconia implant prostheses fabricated on 4 implants.
        J Prosthet Dent. 2018; 119: 409-416
        • Rocha R.
        • Pinheiro A.L.
        • Villaverde A.B.
        Flexural strength of pure Ti, Ni-Cr and Co-Cr alloys submitted to Nd:YAG laser or TIG welding.
        Braz Dent J. 2006; 17: 20-23
        • Svanborg P.
        • Stenport V.
        • Eliasson A.
        Fit of cobalt-chromium implant frameworks before and after ceramic veneering in comparison with CNC-milled titanium frameworks.
        Clin Exp Dent Res. 2015; 26: 49-56
        • Lopes S.C.
        • Pagnano V.O.
        • Rollo J.M.
        • Leal M.B.
        • Bezzon O.L.
        Correlation between metal-ceramic bond strength and coefficient of linear thermal expansion difference.
        J Appl Oral Sci. 2009; 17: 122-128
        • Antanasova M.
        • Kocjan A.
        • Kovač J.
        • Žužek B.
        • Jevnikar P.
        Influence of thermo-mechanical cycling on porcelain bonding to cobalt - chromium and titanium dental alloys fabricated by casting, milling, and selective laser melting.
        J Prosthodont Res. 2018; 62: 184-194
        • Yilmaz B.
        • Kale E.
        • Johnston W.M.
        Marginal discrepancy of CAD-CAM complete-arch fixed implant-supported frameworks.
        J Prosthet Dent. 2018; 120: 65-70
        • Katsoulis J.
        • Mericske-Stern R.
        • Enkling N.
        • Katsoulis K.
        • Blatz M.B.
        In vitro precision of fit of computer-aided designed and computer-aided manufactured titanium screw-retained fixed dental prostheses before and after ceramic veneering.
        Clin Oral Implants Res. 2015; 26: 44-49
        • Katsoulis J.
        • Müller P.
        • Mericske-Stern R.
        • Blatz M.B.
        CAD/CAM fabrication accuracy of long- vs. short-span implant-supported FDPs.
        Clin Oral Implants Res. 2015; 26: 245-249
        • Antanasova M.
        • Kocjan A.
        • Hočevar M.
        • Jevnikar P.
        Influence of surface airborne-particle abrasion and bonding agent application on porcelain bonding to titanium dental alloys fabricated by milling and by selective laser melting.
        J Prosthet Dent. 2020; 123: 491-499
        • Presotto A.G.C.
        • Oliveira L.V.
        • Pisani M.X.
        • Barão V.A.R.
        • Mesquita M.F.
        Influence of spark erosion on the fit of screw-retained Co-Cr fixed complete denture frameworks veneered with different materials.
        J Prosthet Dent. 2018; 119: 797-803
        • Rodrigues S.A.
        • Presotto A.G.C.
        • Barão V.A.R.
        • Consani R.L.X.
        • Nóbilo M.A.A.
        • Mesquita M.F.
        The role of welding techniques in the biomechanical behavior of implant-supported prostheses.
        Mater Sci Eng C. 2017; 78: 435-442
        • Fischer J.
        • Thoma A.
        • Suter A.
        • Lüthy H.
        • Luder H.-U.
        • Hämmerle C.H.-F.
        Misfit of suprastructures on implants processed by electrical discharge machining or the Cresco method.
        Quintessence Int. 2009; 40: 515-522
        • Eisenmann E.
        • Mokabberi A.
        • Walter M.H.
        • Freesmeyer W.B.
        Improving the fit of implant-supported superstructures using the spark erosion technique.
        Int J Oral Maxillofac Implants. 2004; 19: 810-818
        • Sartori I.A.D.M.
        • Ribeiro R.F.
        • Francischone C.E.
        • De Mattos M.D.G.C.
        In vitro comparative analysis of the fit of gold alloy or commercially pure titanium implant-supported prostheses before and after electroerosion.
        J Prosthet Dent. 2004; 92: 132-138
        • Gomes É.A.
        • Tiossi R.
        • Lapria Faria A.C.
        • Rodrigues R.C.S.
        • Faria Ribeiro R.
        Torque loss under mechanical cycling of long-span zirconia and titanium-cemented and screw-retained implant-supported CAD/CAM frameworks.
        Clin Oral Implants Res. 2014; 25: 1395-1402
        • Bhering C.L.
        • Marques I.S.V.
        • Takahashi J.M.
        • Barão V.A.
        • Consani R.L.
        • Mesquita M.F.
        The effect of casting and masticatory simulation on strain and misfit of implant-supported metal frameworks.
        Mater Sci Eng C Mater Biol Appl. 2016; 62: 746-751
        • Tiossi R.
        • Gomes É.A.
        • Faria A.C.L.
        • Rodrigues R.C.S.
        • Ribeiro R.F.
        Influence of cyclic fatigue in water on screw torque loss of long-span one-piece implant-supported zirconia frameworks.
        J Prosthodont. 2017; 26: 315-320
        • Jemt T.
        Failures and complications in 391 consecutively inserted fixed prostheses supported by Brånemark implants in edentulous jaws: a study of treatment from the time of prosthesis placement to the first annual checkup.
        Int J Oral Maxillofac Implants. 1991; 6: 270-276
        • Presotto A.G.C.
        • Barão V.A.R.
        • Bhering C.L.B.
        • Mesquita M.F.
        Dimensional precision of implant-supported frameworks fabricated by 3D printing.
        J Prosthet Dent. 2019; 122: 38-45
        • Machado A.C.M.
        • Cardoso L.
        • Brandt W.C.
        • Henriques G.E.P.
        • De Arruda Nóbilo M.A.
        Photoelastic analysis of the distribution of stress in different systems of overdentures on osseous-integrated implants.
        J Craniofac Surg. 2011; 22: 2332-2336
        • Celik G.
        • Uludag B.
        Photoelastic stress analysis of various retention mechanisms on 3-implant-retained mandibular overdentures.
        J Prosthet Dent. 2007; 97: 229-235
        • Spazzin A.O.
        • Henrique G.E.
        • Nóbilo M.A.
        • Consani R.L.
        • Correr-Sobrinho L.
        • Mesquita M.F.
        Effect of retorque on loosening torque of prosthetic screws under two levels of fit of implant-supported dentures.
        Braz Dent J. 2010; 21: 12-17
        • Byrne D.
        • Jacobs S.
        • O'Connell B.
        • Houston F.
        • Claffey N.
        Preloads generated with repeated tightening in three types of screws used in dental implant assemblies.
        J Prosthodont. 2006; 15: 164-171
        • Bacchi A.
        • Regalin A.
        • Bhering C.L.B.
        • Alessandretti R.
        • Spazzin A.O.
        Loosening torque of universal abutment screws after cyclic loading: influence of tightening technique and screw coating.
        J Adv Prosthodont. 2015; 7: 375-379
        • International Organization for Standardization
        ISO 9693-1. Dentistry compatibility testing. Part 1: metal-ceramic systems.
        International Organization for Standardization, Geneva2012 (ISO Store Order: OP-184149 (Date: 2017-06-09). Available at:)