Research and Education| Volume 113, ISSUE 5, P398-404, May 2015

Download started.


Die spacer thickness reproduction for central incisor crown fabrication with combined computer-aided design and 3D printing technology: An in vitro study


      Statement of problem

      The inability to control die spacer thickness has been reported. However, little information is available on the congruency between the computer-aided design parameters for die spacer thickness and the actual printout.


      The purpose of this study was to evaluate the accuracy and precision of the die spacer thickness achieved by combining computer-aided design and 3-dimensional printing technology.

      Material and methods

      An ivorine maxillary central incisor was prepared for a ceramic crown. The prepared tooth was duplicated by using polyvinyl siloxane duplicating silicone, and 80 die-stone models were produced from Type IV dental stone. The dies were randomly divided into 5 groups with assigned die spacer thicknesses of 25 μm, 45 μm, 65 μm, 85 μm, and 105 μm (n=16). The printed resin copings, obtained from a printer (ProJet DP 3000; 3D Systems), were cemented onto their respective die-stone models with self-adhesive resin cement and stored at room temperature until sectioning into halves in a buccolingual direction. The internal gap was measured at 5 defined locations per side of the sectioned die. Images of the printed resin coping/die-stone model internal gap dimensions were obtained with an inverted bright field metallurgical microscope at ×100 magnification. The acquired digital image was calibrated, and measurements were made using image analysis software. Mixed models (α=.05) were used to evaluate accuracy. A false discovery rate at 5% was used to adjust for multiple testing. Coefficient of variation was used to determine the precision for each group and was evaluated statistically with the Wald test (α=.05).


      The accuracy, expressed in terms of the mean differences between the prescribed die spacer thickness and the measured internal gap (standard deviation), was 50 μm (11) for the 25 μm group simulated die spacer thickness, 30 μm (10) for the 45 μm group, 15 μm (14) for the 65 μm group, 3 μm (23) for the 85 μm group, and -10 μm (32) for the 105 μm group. The precision mean of the measurements, expressed as a coefficient of variation, ranged between 14% and 33% for the 5 groups.


      For the accuracy evaluation, statistically significant differences were found for all the groups, except the group of 85 μm. For the precision assessment, the coefficient of variation was above 10% for all groups, showing the printer’s inability to reproduce the uniform internal gap within the same group.
      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.
        • O’Neal S.J.
        • Monteiro J.
        • Miller C.
        • Roan Jr., J.D.
        • Cohen K.S.
        Techniques to improve the seating of castings.
        J Am Dent Assoc. 1978; 96: 432-437
        • Carter S.M.
        • Wilson P.R.
        The effect of die-spacing on crown retention.
        Int J Prosthodont. 1996; 9: 21-29
        • Grajower R.
        • Zuberi Y.
        • Lewinstein I.
        Improving the fit of crowns with die spacers.
        J Prosthet Dent. 1989; 61: 555-563
        • Wang C.J.
        • Millstein P.L.
        • Nathanson D.
        Effects of cement, cement space, marginal design, seating aid materials, and seating force on crown cementation.
        J Prosthet Dent. 1992; 67: 786-790
        • Carter S.M.
        • Wilson P.R.
        The effects of die-spacing on post-cementation crown elevation and retention.
        Aust Dent J. 1997; 42: 192-198
        • Cho S.H.
        • Chang W.G.
        • Lim B.S.
        • Lee Y.K.
        Effect of die spacer thickness on shear bond strength of porcelain laminate veneers.
        J Prosthet Dent. 2006; 95: 201-208
        • Cooper T.M.
        • Christensen G.J.
        • Laswell H.R.
        • Baxter R.
        Effect of venting on cast gold full crowns.
        J Prosthet Dent. 1971; 26: 621-626
        • Miller G.D.
        • Tjan A.H.
        The internal escape channel: a solution to incomplete seating of full cast crowns.
        J Am Dent Assoc. 1982; 104: 322-324
        • Aditya P.
        • Madhav V.N.
        • Bhide S.V.
        • Aditya A.
        Marginal discrepancy as affected by selective placement of die-spacer: an in vitro study.
        J Indian Prosthodont Soc. 2012; 12: 143-148
        • Passon C.
        • Lambert R.H.
        • Lambert R.L.
        • Newman S.
        The effect of multiple layers of die-spacer on crown retention.
        Oper Dent. 1992; 17: 42-49
        • Gegauff A.G.
        • Rosenstiel S.F.
        Reassessment of die-spacer with dynamic loading during cementation.
        J Prosthet Dent. 1989; 61: 655-658
        • Campagni W.V.
        • Wright W.
        • Martinoff J.T.
        Effect of die spacer on the seating of complete cast gold crowns with grooves.
        J Prosthet Dent. 1986; 55: 324-328
        • Campagni W.V.
        • Preston J.D.
        • Reisbick M.H.
        Measurement of paint-on die spacers used for casting relief.
        J Prosthet Dent. 1982; 47: 606-611
        • Psillakis J.J.
        • McAlarney M.E.
        • Wright R.F.
        • Urquiola J.
        • MacDonald D.E.
        Effect of evaporation and mixing technique on die spacer thickness: a preliminary study.
        J Prosthet Dent. 2001; 85: 82-87
        • Tuntiprawon M.
        • Wilson P.R.
        The effect of cement thickness on the fracture strength of all-ceramic crowns.
        Aust Dent J. 1995; 40: 17-21
        • Jorgensen K.D.
        • Esbensen A.L.
        The relationship between the film thickness of zinc phosphate cement and retention of veneer crowns.
        Acta Odontol Scand. 1968; 26: 169-175
        • Vermilyea S.G.
        • Kuffler M.J.
        • Huget E.F.
        The effects of die relief agent on the retention of full coverage castings.
        J Prosthet Dent. 1983; 50: 207-210
        • McLean J.W.
        • von Fraunhofer J.A.
        The estimation of cement film thickness by an in vivo technique.
        Br Dent J. 1971; 131: 107-111
        • Chan D.C.
        • Wilson Jr., A.H.
        • Barbe P.
        • Cronin Jr., R.J.
        • Chung C.
        • Chung K.
        Effect of preparation convergence on retention and seating discrepancy of complete veneer crowns.
        J Oral Rehabil. 2004; 31: 1007-1013
        • Hollenback G.M.
        Precision gold inlays made by a simple technic.
        J Am Dent Assoc. 1943; 30: 99-109
        • Campbell S.D.
        Comparison of conventional paint-on die spacers and those used with the all-ceramic restorations.
        J Prosthet Dent. 1990; 63: 151-155
        • Oliva R.A.
        • Lowe J.A.
        Effect of die spacer on the seating of cast restorations on composite core preparations.
        J Prosthet Dent. 1987; 58: 29-35
        • Kokubo Y.
        • Nagayama Y.
        • Tsumita M.
        • Ohkubo C.
        • Fukushima S.
        • Vult von Steyern P.
        Clinical marginal and internal gaps of In-Ceram crowns fabricated using the GN-I system.
        J Oral Rehabil. 2005; 32: 753-758
        • Moldovan O.
        • Luthardt R.G.
        • Corcodel N.
        • Rudolph H.
        Three-dimensional fit of CAD/CAM-made zirconia copings.
        Dent Mater. 2011; 27: 1273-1278
        • Cooper K.G.
        Rapid prototyping technology.
        Marcel Dekker, New York2005: 1-8
        • Bhaskaran E.
        • Azhagarasan N.S.
        • Miglani S.
        • Ilango T.
        • Krishna G.P.
        • Gajapathi B.
        Comparative evaluation of marginal and internal gap of Co-Cr copings fabricated from conventional wax pattern, 3D printed resin pattern and DMLS Tech: an in vitro study.
        J Indian Prosthodont Soc. 2013; 13: 189-195
        • Beuer F.
        • Aggstaller H.
        • Richter J.
        • Edelhoff D.
        • Gernet W.
        Influence of preparation angle on marginal and internal fit of CAD/CAM-fabricated zirconia crown copings.
        Quintessence Int. 2009; 40: 243-250
        • Alghazzawi T.F.
        • Liu P.R.
        • Essig M.E.
        The effect of different fabrication steps on the marginal adaptation of two types of glass-infiltrated ceramic crown copings fabricated by CAD/CAM technology.
        J Prosthodont. 2012; 21: 167-172
        • Martorelli M.
        • Gerbino S.
        • Giudice M.
        • Ausiello P.
        A comparison between customized clear and removable orthodontic appliances manufactured using RP and CNC techniques.
        Dent Mater. 2013; 29: e1-10
        • Öhman C.
        • Baleani M.
        • Viceconti M.
        Repeatability of experimental procedures to determine mechanical behaviour of ligaments.
        Acta Bioeng Biomech. 2009; 11: 19-23
        • Gousard J.
        • Lechevrel C.
        • Martin P.M.
        • Rousel G.
        Comparison of monoclonal antibodies and tritated ligands for estrogen receptor asays in 241 breast cancer cytosols.
        Cancer Res. 1986; 46: 4282-4287
        • Jensen P.J.
        • Andersen P.K.
        • Thøgersen C.
        The reproducibility of measurement of right ventricular ejection fraction and cardiac output by the thermodilution technique in patients on mechanical ventilation.
        Acta Anaesthesiol Scand. 1994; 38: 486-489
        • Olivera A.B.
        • Saito T.
        The effect of die spacer on retention and fitting of complete cast crowns.
        J Prosthodont. 2006; 15: 243-249
      1. Certification programs of the Council on Dental Materials, Instruments and Equipment. Specification No. 8. American National Standards Institution/American Dental Association, Chicago1977
        • Wood K.C.
        • Berzins D.W.
        • Luo Q.
        • Thompson G.A.
        • Toth J.M.
        • Nagy W.W.
        Resistance to fracture of two all-ceramic crown materials following endodontic access.
        J Prosthet Dent. 2006; 95: 33-41
        • Holmes J.R.
        • Bayne S.C.
        • Holland G.A.
        • Sulik W.D.
        Considerations in measurement of marginal fit.
        J Prosthet Dent. 1989; 62: 405-408
        • Nawafleh N.A.
        • Mack F.
        • Evans J.
        • Mackay J.
        • Hatamleh M.M.
        Accuracy and reliability of methods to measure marginal adaptation of crowns and FDPs: a literature review.
        J Prosthodont. 2013; 22: 419-428
        • Subrahmanya Nairy K.
        • Aruna Rao K.
        Tests of coefficients of variation of normal population.
        Commun Stat Simul Comput. 2003; 32: 641-661