Journal of Prosthetic Dentistry
Research Article| Volume 87, ISSUE 1, P30-39, January 2002

Defects in hexed gold prosthetic screws: A metallographic and tensile analysis


      Statement of Problem. Prosthetic gold screw fracture remains a clinical problem in implant prosthodontics. Purpose. This study examined hexed gold prosthetic screws for internal defects and determined the effect of these defects on tensile strength. The microstructure, microhardness, and major constituents of the alloys also were determined. Material and Methods. Four intact hexed gold prosthetic screws, 1 from each of 2 different lots from 2 manufacturers (Implant Innovations and Nobel Biocare), were examined with standard metallographic techniques for defects, microstructure, microhardness, and major alloy constituents. Thirty-six screws, 9 from each of the 2 different lots of both manufacturers, were subjected to tensile testing to determine fracture load values. Analysis of variance and Tukey tests were used to identify differences between manufacturers and lots (P<.05). The fracture sites were examined retrospectively with a scanning electron microscope to identify defects that could have contributed to failure. The mode of fracture was characterized. Results. There were no significant defects in the screws tested, but differences were observed in the microstructure, microhardness, alloy composition, and fracture load values for both manufacturers. Screws from the 2 manufacturers demonstrated distinctly different metallurgical characteristics, which highlighted differences in the manufacturing processes. Fracture load values ranged from 850 ± 20 N to 1093 ± 64 N. A significant difference was noted for mean fracture load values for the different lots of Implant Innovations screws (P<.05). Ductile fracture was the mode of failure. Conclusion. The results of this study suggest that variability in the physical properties of similar hexed gold prosthetic screws made by different manufacturers, as well as different lots from the same manufacturer, may affect clinical success. (J Prosthet Dent 2002;87:30-9.)
      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


        • Zarb GA
        • Schmitt A.
        The longitudinal clinical effectiveness of osseointegrated dental implant: the Toronto study. Part III: Problems and complications encountered.
        J Prosthet Dent. 1990; 64: 185-194
        • Naert I
        • Quirynen M
        • vanSteenberghe D
        • Darius P.
        A study of 589 consecutive implants supporting complete fixed prostheses. Part II: Prosthetic aspects.
        J Prosthet Dent. 1992; 68: 949-956
        • Sones AD.
        Complications with osseointegrated implants.
        J Prosthet Dent. 1989; 62: 581-585
        • Gunne J
        • Jemt T
        • Linden B.
        Implant treatment in partially edentulous patients: a report on prostheses after 3 years.
        Int J Prosthodont. 1994; 7: 143-148
        • Eckert SE
        • Wollan PC.
        Retrospective review of 1170 endosseous implants placed in partially edentulous jaws.
        J Prosthet Dent. 1998; 79: 415-421
        • Binon P
        • Sutter F
        • Beaty K
        • Brunski J
        • Gulbransen H
        • Weiner R.
        The role of screws in implant systems.
        Int J Oral Maxillofac Implants. 1994; : 48-63
        • Rangert B
        • Eng M
        • Jemt T
        • Jorneus L.
        Forces and moments on Brånemark implants.
        Int J Oral Maxillofac Implants. 1989; 4: 241-247
        • Goodacre CJ
        • Kan JY
        • Rungcharassaeng K.
        Clinical complications of osseointegrated implants.
        J Prosthet Dent. 1999; 81: 537-552
        • Jorneus L
        • Jemt T
        • Carlsson L.
        Load and designs of screw joints for single crowns supported by osseointegrated implants.
        Int J Oral Maxillofac Implants. 1992; 7: 353-359
        • Jaarda MJ
        • Razzoog ME
        • Gratton DG.
        Comparison of “look-alike” implant prosthetic retaining screws.
        J Prosthodont. 1995; 4: 23-27
        • Breeding LC
        • Dixon DL
        • Nelson EW
        • Tielge JD.
        Torque required to loosen single-tooth implant abutment screws before and after simulated function.
        Int J Prosthodont. 1993; 6: 435-439
        • Patterson EA
        • Johns RB.
        Theoretical analysis of fatigue life of fixture screws in osseointegrated dental implants.
        Int J Oral Maxillofac Implants. 1992; 7: 26-33
        • Weinberg LA
        • Kruger B.
        A comparison of implant/prosthesis loading with four clinical variables.
        Int J Prosthodont. 1995; 8: 421-433
        • Jaarda MJ
        • Razzoog ME
        • Gratton DG.
        Effect of preload torque on the ultimate tensile strength of implant prosthetic retaining screws.
        Implant Dent. 1994; 3: 17-21
        • Haack JE
        • Sakaguchi RL
        • Sun T
        • Coffey JP.
        Elongation and preload stress in dental implant abutment screws.
        Int J Oral Maxillofac Implants. 1995; 10: 529-536
        • Colangelo VJ
        • Heiser FA.
        Analysis of metallurgical failures.
        in: 2nd ed. John Wiley and Sons, New York1987: 136
        • Anusavice KJ.
        Phillip's science of dental materials.
        in: 10th ed. WB Saunders Co, Philadelphia1996: 49-74
        • Jaarda MJ
        • Razzoog ME
        • Gratton DG.
        Ultimate tensile strength of five interchangeable prosthetic retaining screws.
        Implant Dent. 1996; 5: 16-19
        • Mills K.
        Metals handbook. 9th ed. Metallography and microstructure. Vol. 9. American Society for Metals, Materials Park (OH)1985: 30
        • Chandler H.
        Metallurgy for the non-metallurgist.
        in: American Society for Metals International, Materials Park (OH)1998: 254
        • Henkel D
        • Pense AW.
        Structure and properties of engineering materials.
        in: 5th ed. McGraw Hill, Boston1977: 101-103 (44-57)
        • Aligizaki KK
        • Tittmann BR
        • Gordon GA.
        Comparison between optical microscopy and scanning acoustic microscopy for detecting flaws in concrete.
        Experimental Techniques. 1994; 18: 24-28
        • Khuri-Yakub BT.
        Scanning acoustic microscopy.
        Ultrasonics. 1993; 31: 361-372
        • Dalton WK.
        The technology of metallurgy.
        in: Macmillan Publishing Co, Hampshire1994: 254-272