The laser welding technique applied to the non precious dental alloys procedure and results

Abstract

RESEARCHprosthodontics have a laser in their laboratory. However, looking at the available literature, since 1970 many experiments have been conducted into non precious and precious alloys and have shown contradictory results, probably because the experimental procedures used were different. 15,16,17,18,19 Therefore no comparison could be made. In this study, the weldability of three non precious alloys was investigated. The procedure consisted of determining the appropriate welding parameters which could achieve a deep joining in depth without cracks or gas entrapments in the welding area. The quality of the joining was checked by metallographic observations on polished sections. Wires of different diameters were then laser-welded and tested in tension. In order to understand the different behaviours between the three alloys (2 Ni-Cr and 1 Co-Cr based alloys), the composition of the welded area was determined by a X-Ray microprobe. Particular attention was given to the role played by the impurities. Methods Chemical compositionsTwo Ni-Cr-Mo alloys and 1 Co-Cr-Mo alloy, manufactured by Dentaurum (Pforzheim, Germany) were chosen for their applications in the dental field (Table 1) : 1 G mou is a low cost alloy used for crowns and bridges. 2 Remanium Cs is used for ceramic fixed partial dentures. 3 GM 800 is a cobalt chrominium alloy used for removable and fixed partial dentures Laser parameters and welding conditionsIn order to determine the welding conditions against the metal thickness and the ability of the laser device, two series of cast wires (0.6 to 2 mm thick), and five specimen DIN 50125 (3mm thick) were prepared by investment casting. The samples were then cut, joined by hand, edge to edge and welded without fillers or fluxes, using a commercial Nd-Yag laser (DL 2002 manufactured by Dentaurum) whose technical characteristics are given in table 2. In order to avoid the laser beam reflection and to improve the weld penetration, all the wires were sand-blasted with alumina powders and welded under Argon shielding atmosphere to decrease the oxidation contamination. All the samples were welded using the same procedure. The Laser conditions depend on the thickness and the volume of material to be welded (Table 2).Each wire was first assembled by the 4-cardinal points and thenThe laser welding technique applied to the non precious dental alloys procedure and results Aim The laser welding technique was chosen for its versatility in the repair of dental metal prosthesis. The aim of this research is to assess the accuracy, quality and reproducibility of this technique as applied to Ni-Cr-Mo and Cr-Co-Mo alloys often used to make prosthesis Method The alloy's ability to weld was evaluated with a pulsed Nd-Yag Laser equipment. In order to evaluate the joining, various cast wires with different diameters were used. The efficiency of the joining was measured with tensile tests. In order to understand this difference, metallographic examinations and XRay microprobe analysis were performed through the welded area and c...

Physico-mechanical properties and prosthodontic applications of Co-Cr dental alloys: a review of the literature

“…Pulsed laser welding devices can be used to join broken parts of a Co-Cr removable partial denture with soldering wires with a composition similar to that of the Co-Cr alloy, thus eliminating the adverse effect of galvanic coupling. Nevertheless, laser welding demonstrates other advantages, combining a rapid, economic, and accurate way for joining metals and alloys 45. However, laser welding is more technique-sensitive, and the optimization of the technique requires the training of the dental technician, especially for the identification of appropriate welding conditions 46…”

Laser Welding and Syncristallization Techniques Comparison:In VitroStudy

“…Moreover, the heat source is a concentrated high-power light beam, so minimizing distortion problems in the prosthetic pieces [3]. The process allows the possibility of welding adjacent to acrylic resin or ceramic parts with neither physical (cracking) nor colour damage [4], thereby allowing a reduction of working time by eliminating the necessity to remake broken prosthetic or orthodontic appliances. …”

Laser Welded versus Resistance Spot Welded Bone Implants: Analysis of the Thermal Increase and Strength

“…The process allows the possibility of welding in proximity to acrylic resins or ceramic parts with no physical (cracking) or colour damage [30] and these characteristics diminish the working time through the elimination of the necessity for the remaking of broken prosthetic or orthodontic appliances. Several works based on laboratory tests have concluded that laser-welded joints have a high, reproducible strength [31].…”