Comparative study on torsional strength, ductility and fracture characteristics of laser-welded α + β Ti–6Al–7Nb alloy, CP Titanium and Co–Cr alloy dental castings

Abstract Objectives The purpose of this study was to compare torsional strength, ductility and fracture behaviors of Ti–6Al–7Nb, CP Ti and Co–Cr alloy castings after laser welding. Methods Dumbbell-shaped castings of three metal alloys (Ti–6Al–7Nb alloy, CP Ti, Co–Cr alloy) were cut in half and laser welded with a Nd:YAG pulse laser-welding machine at either 220 V or 260 V of laser voltage. After being laser welded, all cast specimens were tested with a multi-axial hydraulic testing machine (MTS 858 Mini Bionix ® ) using a torsional test. The fracture surfaces were investigated with a scanning electron microscope. Results None of the laser-welded Ti–6Al–7Nb alloy and CP Ti castings was broken within the welded joint, showing torsional strength as high as the unwelded castings. Unlike the other groups, the laser-welded Co–Cr alloy castings exhibited brittle fracture appearance and provided substantially less torsional strength. Significance The torsional strength of the laser-welded Ti–6Al–7Nb alloy and CP Ti castings was as high as that of the unwelded castings while this finding could not apply to the Co–Cr alloy castings. This indicates that the mechanical strength of the laser-welded Ti–6Al–7Nb alloy dental casting is sufficient for clinical applications.

[1]  R. Wang,et al.  Thermal modeling of laser welding for titanium dental restorations. , 1998, The Journal of prosthetic dentistry.

[2]  M Atsuta,et al.  Joint strength of laser-welded titanium. , 2002, Dental materials : official publication of the Academy of Dental Materials.

[3]  Toshiko Mori,et al.  Titanium for removable partial dentures (III): 2‐year clinical follow‐up in an undergraduate programme , 2000 .

[4]  T E Gordon,et al.  Laser welding of prostheses--an initial report. , 1970, Quintessence international.

[5]  K. Böning,et al.  Studies on laser- and plasma-welded titanium. , 1993, Dental materials : official publication of the Academy of Dental Materials.

[6]  C. Daly,et al.  Fatigue life of a Nd:YAG laser-welded metal ceramic alloy. , 1997, The International journal of prosthodontics.

[7]  L Albingre,et al.  Prosthodontics: The laser welding technique applied to the non precious dental alloys procedure and results , 2001, British Dental Journal.

[8]  E. Dootz,et al.  Mechanical properties of laser-welded cast and wrought titanium. , 1995, The Journal of prosthetic dentistry.

[9]  T. Chai,et al.  Mechanical properties of laser-welded cast titanium joints under different conditions. , 1998, The Journal of prosthetic dentistry.

[10]  T. Yamagishi,et al.  Mechanical properties of laser welds of titanium in dentistry by pulsed Nd:YAG laser apparatus. , 1993, The Journal of prosthetic dentistry.

[11]  B. Jackson.  The use of laser-welded titanium framework technology: a case report for the totally edentulous patient. , 2005, The Journal of oral implantology.

[12]  M. Kikuchi,et al.  Mechanical properties and grindability of dental cast Ti-Nb alloys. , 2003, Dental materials journal.

[13]  J Chai,et al.  Marginal fit of machine-milled titanium and cast titanium single crowns. , 1994, The International journal of prosthodontics.

[14]  Ignace Naert,et al.  Implant-supported laser-welded titanium and conventional cast frameworks in the partially edentulous law: a 5-year prospective multicenter study. , 2003, The International journal of prosthodontics.

[15]  Kouich Watanabe,et al.  Internal porosity of cast titanium removable partial dentures: influence of sprue direction and diameter on porosity in simplified circumferential clasps. , 2005, Dental materials : official publication of the Academy of Dental Materials.

[16]  H. Doi,et al.  Deformation properties of Ti-6A1-7Nb alloy castings for removable partial denture frameworks. , 2004, Dental materials journal.

[17]  Ikuya Watanabe,et al.  Laser welding of cast titanium and dental alloys using argon shielding. , 2006, Journal of prosthodontics : official journal of the American College of Prosthodontists.

[18]  J. Rubenstein.  Stereo laser-welded titanium implant frameworks: clinical and laboratory procedures with a summary of 1-year clinical trials. , 1995, The Journal of prosthetic dentistry.

[19]  John S. Huling,et al.  Comparative Distortion in Three-Unit Fixed Prostheses Joined by Laser Welding, Conventional Soldering, or Casting in One Piece , 1977, Journal of dental research.

[20]  G. Welsch,et al.  Joining titanium materials with tungsten inert gas welding, laser welding, and infrared brazing. , 1995, The Journal of prosthetic dentistry.

[21]  N Kurosaki,et al.  Wear properties of Ti and Ti-6Al-7Nb castings for dental prostheses. , 2003, Biomaterials.

[22]  S. Guttal,et al.  Cast titanium overlay denture for a geriatric patient with a reduced vertical dimension. , 2005, Gerodontology.

[23]  Takao Hanawa,et al.  Mechanical strength and microstructure of laser-welded Ti-6Al-7Nb alloy castings. , 2005, Dental materials journal.

[24]  D. Givan,et al.  Torsional properties of implant grade titanium. , 1991, Journal of biomedical materials research.

[25]  Ikuya Watanabe,et al.  Tensile strength and elongation of laser-welded Ti and Ti-6AL-7NB. , 2004, Journal of biomedical materials research. Part B, Applied biomaterials.

[26]  T. Okabe,et al.  Effect of corrosion on the strength of soldered titanium and Ti-6Al-4V alloy. , 1996, Dental materials : official publication of the Academy of Dental Materials.

[27]  Yasunori Suzuki,et al.  Titanium removable partial denture clasp repair using laser welding: a clinical report. , 2004, The Journal of prosthetic dentistry.

[28]  H Hamanaka,et al.  Mechanical properties and corrosion resistance of Ti–6Al–7Nb alloy dental castings , 1998, Journal of materials science. Materials in medicine.

[29]  E. Angelini,et al.  Corrosion resistance of solder joints for removable partial dentures. , 1988, Dental materials : official publication of the Academy of Dental Materials.

[30]  O. Sandven,et al.  Laser welding in the dental laboratory: an alternative to soldering. , 1996, Journal of dental technology : the peer-reviewed publication of the National Association of Dental Laboratories.

[31]  M. Bergman,et al.  Laser welding of titanium in dentistry. , 1988, Acta odontologica Scandinavica.

[32]  J. Nicholls,et al.  Laser welding of a cobalt-chromium removable partial denture alloy. , 1998, The Journal of prosthetic dentistry.

[33]  J. Chai,et al.  Mechanical properties of titanium connectors. , 1996, The International journal of prosthodontics.

[34]  E Berg,et al.  Dentists' opinions on aspects of cast titanium restorations. , 1997, Journal of dentistry.

[35]  M Atsuta,et al.  Mechanical strength of laser-welded cobalt-chromium alloy. , 2004, Journal of biomedical materials research. Part B, Applied biomaterials.

[36]  U. Belser,et al.  Microstructures of brazings and welds using grade 2 commercially pure titanium. , 2001, The International journal of prosthodontics.

[37]  T. Jemt,et al.  Clinical experiences of implant-supported prostheses with laser-welded titanium frameworks in the partially edentulous jaw: a 5-year follow-up study. , 1999, Clinical implant dentistry and related research.