Optimization of operator and physical parameters for laser welding of dental materials.
OBJECTIVE
Interactions between lasers and materials are very complex phenomena. The success of laser welding procedures in dental metals depends on the operator's control of many parameters. The aims of this study were to evaluate factors relating to the operator's dexterity and the choice of the welding parameters (power, pulse duration and therefore energy), which are recognized determinants of weld quality.


METHODS
In vitro laboratory study.


METHODS
FeNiCr dental drawn wires were chosen for these experiments because their properties are well known. Different diameters of wires were laser welded, then tested in tension and compared to the control material as extruded, in order to evaluate the quality of the welding. Scanning electron microscopy of the fractured zone and micrograph observations perpendicular and parallel to the wire axis were also conducted in order to analyse the depth penetration and the quality of the microstructure. Additionally, the micro-hardness (Vickers type) was measured both in the welded and the heat-affected zones and then compared to the non-welded alloy.


RESULTS
Adequate combination of energy and pulse duration with the power set in the range between 0.8 to 1 kW appears to improve penetration depth of the laser beam and success of the welding procedure. Operator skill is also an important variable.


CONCLUSIONS
The variation in laser weld quality in dental FeNiCr wires attributable to operator skill can be minimized by optimization of the physical welding parameters.
Bertrand
C
C
Dental School, Laboratoire 'surface- interface', Université de Nice, Sophia-Antipolis, 24, avenue des diables bleus, 06357 Nice Cedex 04, France. caro.bertrand@wanadoo.fr
le Petitcorps
Y
Y
Albingre
L
L
Dupuis
V
V
D002858:Chromium Alloys / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry*; D012994:Dental Soldering / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D006244:Hardness; D006358:Hot Temperature; D006801:Humans; D007501:Iron / Q000737:chemistry; D007834:Lasers; D008855:Microscopy, Electron, Scanning; D009048:Motor Skills; D009969:Orthodontic Wires; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties
D002858:Chromium Alloys; D003722:Dental Alloys; D013193:Stainless Steel; D007501:Iron