Effect of Nd:YAG laser parameters on the penetration depth of a representative Ni–Cr dental casting alloy

Abstract

The effects of voltage and laser beam (spot) diameter on the penetration depth during laser beam welding in a representative nickel-chromium (Ni-Cr) dental alloy were the subject of this study. The cast alloy specimens were butted against each other and laser welded at their interface using various voltages (160-390 V) and spot diameters (0.2-1.8 mm) and a constant pulse duration of 10 ms. After welding, the laser beam penetration depths in the alloy were measured. The results were plotted and were statistically analyzed with a two-way ANOVA, employing voltage and spot diameter as the discriminating variables and using Holm-Sidak post hoc method (a = 0.05). The maximum penetration depth was 4.7 mm. The penetration depth increased as the spot diameter decreased at a fixed voltage and increased as the voltage increased at a fixed spot diameter. Varying the parameters of voltage and laser spot diameter significantly affected the depth of penetration of the dental cast Ni-Cr alloy. The penetration depth of laser-welded Ni-Cr dental alloys can be accurately adjusted based on the aforementioned results, leading to successfully joined/repaired dental restorations, saving manufacturing time, reducing final cost, and enhancing the longevity of dental prostheses.

Mechanical and interfacial characterization of laser welded Co-Cr alloy with different joint configurations

“…The quality of laser welded joints is dependent on a variety of factors 16 and the current knowledge is limited to only a few of them. Dental technicians and operators are provided with only a few general guidelines for laser welding procedures but these are far from a widely accepted consensus including framework dimensions, materials type, joint geometry and laser conditions to achieve more reliable joints.…”

“…pulse shape, mean power, pulse energy), the use of shielding gas and the dental technician's skill and experience. 15 , 16 , 17 , 18 The cross-section of the dental framework to be welded becomes important due to the relatively shallow melting depth of laser welding. In the case of thin metallic objects such as clasps or frameworks of removable partial dentures, substantial melting depth can be achieved by laser welding of sectioned faces butted against each other.…”

“…While laser pulses with increased power deepen the melting depth, they adversely affect the extent of surface and internal porosity. 16 , 18 , 19 To overcome this limitation, the use of different shaped weld seams (i.e I, Y, X, V) in combination with filler metals has been proposed. 10 , 19 The latter weld seams are named after the shape formed when the two surfaces are butted against each other.…”

Influence of the frameworks of implant-supported prostheses and implant connections on stress distribution

“…6,7 Laser welding has been introduced to dental laboratory procedures as an alternative method to soldering, brazing or TIG welding. 8 Yttrium aluminum garnet (YAG) doped with neodymium (Nd) crystals is used to emit laser beams (the Nd:YAG laser) to weld dental alloys. 9 As the laser energy can be concentrated on a small area, minimal heating or oxidation effects occur in the region surrounding the welded spot; however, this method presents variable resistance results.…”