Abstract
Most wrought wire clasps are attached to the framework of removable partial dentures by soldering. The purpose of this study is to investigate the influence of soldering procedures on deformation and mechanical properties of clasp arms and strength of jointing parts.
In this study, circular clasp arms were made from Co-Cr alloy wires and soldered to supporting parts with a silver solder. Two kinds of temporary attachments, investing and spot welding, and two kinds of soldering methods, torch and electric resistance soldering were applied. These temporary attachment and soldering methods were combined, then four different procedures were compared.
The results were follows.
1. The change of distance between clasp tips during soldering procedure was smaller for temporary attachment by investing than spot welding, and for electric soldering than torch soldering.
2. By any soldering procedure, load required for 0.1 mm deflection of clasp arms increased significantly and permanent deformation after 0.5 mm deflection of them decreased considerably.
3. In both tensile strength and fatigue profile of jointing part, combination of spot welding and electric soldering was the best of all procedures.
These results indicated that without the deformation of clasp arms, combination of spot welding and electric resistance soldering was the most effective procedure in wrought wire clasp construction.
