Abstract

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 X-Ray microprobe analysis were performed through the welded area and compared with the cast part.

Results It was found that a very slight change in the chemistry of the Ni-Cr alloys had a strong influence on the quality of the joining. The Co-Cr alloy presented an excellent weldability. A very important change in the microstructure due to the effect of the laser was pointed out in the welding zone, increasing its micro-hardness.

Conclusion The higher level of carbon and boron in one of the two Ni-Cr was found to be responsible for its poor welding ability. However for the others, the maximum depth of welding was found to be around 2mm which is one of the usual thicknesses of the components which have to be repaired.

1. Doctor, Dental School, Laboratoire Odontologique de Recherche, 16 à 20 Cours de la Marne, 33800 Bordeaux Cedex France
2. Professor in Biomaterials and Chemistry, ICMCB-CNRS, 87, Avenue du docteur A. Schweitzer, 33608 Pessac France
3. Ingineer, ICMCB-CNRS, 87, Avenue du docteur A. Schweitzer, 33608 Pessac France
4. Professor, Dental School, Laboratoire Odontologique de Recherche, 16 à 20 Cours de la Marne, 33800 Bordeaux Cedex France

Correspondence to: C Bertrand¹ rue de la Mane, 33490 Saint Pierre d'Aurillac-France
e-mail: caro.bertrand2@wanadoo.fr