Journal of Prosthetic Dentistry
Research Article| Volume 95, ISSUE 3, P243-248, March 2006

Download started.


Over-refractory casting technique as an alternative to one-piece multi-unit fixed partial denture frameworks

      Statement of problem

      Soldering has been suggested to achieve acceptable fit of multi-unit fixed partial denture (FPD) frameworks of 3 or more elements. However, distortion of the entire framework may occur.


      The purpose of this study was to evaluate marginal fit in 1-piece-casting FPD frameworks comparing 2 casting techniques: the conventional technique (CT) and the over-refractory technique (ORT). The techniques were evaluated on castings made from commercially pure titanium (CP Ti; Tritan), titanium-aluminum-vanadium (Ti-6Al-4V), and nickel-chromium (Ni-Cr; VeraBond II) alloys.

      Material and methods

      A metal master cast including 3 preparations was created to simulate a 5-unit FPD. The metal cast was duplicated in vinyl polysiloxane for fabrication of 60 working casts. For the CT, 0.7-mm-thick patterns were waxed on the casts using an electrical wax-dipping unit. Patterns were removed from the preparations before investing. For the ORT, the silicone impressions were poured with an investment material (Rematitan for CP Ti and Ti-6Al-4V, and Talladium for Ni-Cr). The patterns were waxed on the refractory casts, and the assembly was invested. Both CT and ORT (n=10), CP Ti, and Ti-6Al-4V frameworks were cast using an arc-melting titanium vacuum-casting machine. The Ni-Cr frameworks were cast using an automated centrifugal-casting machine. The mean marginal discrepancies of the frameworks were measured at the mesial, distal, buccal, and lingual interfaces. Marginal gap measurements were recorded 3 times for each surface to the nearest 0.5 μm using a traveling microscope (×50). The data were analyzed with 2-way analysis of variance, followed by the Tukey HSD test (α=.05).


      Marginal discrepancies for the ORT specimens (82.8 ± 1.7 μm for CP Ti; 64.4 ± 1.3 μm for Ti-6Al-4V; and 77.2 ± 1.5 μm for Ni-Cr) were significantly lower than those obtained for the CT specimens (106.3 ± 2.6 μm for CP Ti; 75.7 ± 0.8 μm for Ti-6Al-4V; 101.9 ± 1.7 μm for Ni-Cr) (P<.05). For both techniques, marginal discrepancies were significantly different among the alloys evaluated, presenting the following order from greatest to least marginal discrepancy: CP Ti, Ni-Cr alloy, and Ti-6Al-4V (P<.05).


      The ORT for multi-unit FPD frameworks demonstrated significantly lower marginal discrepancies than the CT.
      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


        • Eames W.B.
        • MacNamara J.F.
        Evaluation of casting machines for ability to cast sharp margins.
        Oper Dent. 1978; 3: 137-141
        • Schiffleger B.E.
        • Ziebert G.J.
        • Dhuru V.B.
        • Brantley W.A.
        • Sigaroudi K.
        Comparison of accuracy of multiunit one-piece castings.
        J Prosthet Dent. 1985; 54: 770-776
        • Leong D.
        • Chai J.
        • Lautenschlager E.
        • Gilbert J.
        Marginal fit of machine-milled and cast titanium single crowns.
        Int J Prosthodont. 1994; 7: 440-447
        • Samet N.
        • Resheff B.
        • Gelbard S.
        • Stern N.
        A CAD-CAM system for the production of metal copings for porcelain-fused-to-metal restorations.
        J Prosthet Dent. 1995; 73: 457-463
        • Taggart W.H.
        A new and accurate method of making gold inlay.
        Dent Cosmos. 1907; 49: 1117-1119
        • Bruce R.W.
        Evaluation of multiple unit castings for fixed partial dentures.
        J Prosthet Dent. 1964; 14: 939-943
        • Fusayama T.
        • Hosoda H.
        • Wakumoto S.
        A one-piece cast permanent splint.
        J Prosthet Dent. 1966; 16: 572-582
        • Ziebert G.J.
        • Hurtado A.
        • Glapa C.
        • Schiffleger B.E.
        Accuracy of one-piece castings, preceramic and postceramic soldering.
        J Prosthet Dent. 1986; 55: 312-317
        • Hinman R.W.
        • Tesk J.A.
        • Parry E.E.
        • Eden G.T.
        Improving the casting accuracy of fixed partial dentures.
        J Prosthet Dent. 1985; 53: 466-471
        • Huling J.S.
        • Clark E.
        Compratative distortion in three-unit fixed protheses joined by laser welding, conventional soldering, or casting in one-piece.
        J Dent Res. 1977; 56: 128-134
        • Bruno S.A.
        A one-piece fixed bridge.
        J Prosthet Dent. 1955; 5: 401-407
        • Rubin J.G.
        • Sabella A.A.
        One-piece castings for fixed bridgework.
        J Prosthet Dent. 1955; 5: 843-847
        • Fehling A.W.
        • Sansom B.P.
        • Meiser E.T.
        • Johnson P.F.
        Cast connectors: an alternative to soldering base metal alloys.
        J Prosthet Dent. 1986; 55: 195-197
        • Zavanelli R.A.
        • Guilherme A.S.
        • Pessanha-Henriques G.E.
        • de Arruda Nobilo M.A.
        • Mesquita M.F.
        Corrosion-fatigue of laser-repaired commercially pure titanium Ti-6Al-4V under different test environments.
        J Oral Rehabil. 2004; 31: 1029-1034
        • Henriques G.E.
        • Consani S.
        • Rollo J.M.
        • Andrade e Silva F.A.
        Soldering and remelting influence on fatigue strength of cobalt-chromium alloys.
        J Prosthet Dent. 1997; 78: 146-152
        • Fusayama T.
        • Wakumoto S.
        • Hosada H.
        Accuracy of fixed partial dentures made by various soldering techniques and one-piece casting.
        J Prosthet Dent. 1964; 14: 334-342
        • Sarfati E.
        • Harter J.C.
        Comparative accuracy of fixed partial dentures made as one-piece castings or joined by solder.
        Int J Prosthodont. 1992; 5: 377-383
        • Darveniza M.
        • Martin J.R.
        One-piece casting for fixed bridgework.
        Aust Dent J. 1982; 27: 5-10
        • Abramowsky Z.L.
        Fixed partial dentures by one-piece casting.
        J Prosthet Dent. 1960; 10: 938-945
        • Blackman R.
        • Baez R.
        • Barghi N.
        Marginal accuracy and geometry of cast titanium copings.
        J Prosthet Dent. 1992; 67: 435-440
        • Contreras E.F.
        • Henriques G.E.
        • Giolo S.R.
        • Nobilo M.A.
        Fit of cast commercially pure titanium and Ti-6Al-4V alloy crowns before and after marginal refinement by electrical discharge machining.
        J Prosthet Dent. 2002; 88: 467-472
        • Schwartz I.S.
        A review of methods and techniques to improve the fit of cast restorations.
        J Prosthet Dent. 1986; 56: 79-83
        • Guilherme A.S.
        • Henriques G.E.P.
        • Zavanelli R.A.
        • Mesquita M.F.
        Surface roughness and fatigue performance of commercially pure titanium and Ti-6Al-4V alloy after different polishing protocols.
        J Prosthet Dent. 2005; 93: 378-385
        • Fonseca J.C.
        • Henriques G.E.
        • Sobrinho L.C.
        • de Goes M.F.
        Stress-relieving and porcelain firing cycle influence on marginal fit of commercially pure titanium and titanium-aluminum-vanadium copings.
        Dent Mater. 2003; 19: 686-691