Abstract
This study was aimed at determining the effect of the two factors, the type and number of retaining wire, on the fitness of the bridge (Three-unit liner bridge) in the electrical soldering. The three-dimensional distortion of both abutments to the pontic was measured. The results obtained are as follows:
1. During the electrical tacking stage in which AUS and BOND were used, the abutments were displaced by about 10 microns in each direction (X, Y and Z).
2. At the soldering stage, the mesio-distal displacement is greater than the bucco-lingual and vertical displacement, regardless of the type of the retaining wire.
3. The best fitness was obtained when the retaining wire is treated with heat and made of soft stainless AUS with an approximate rate of thremal expansion to that of the soldered metal, and two pieces of wire are used each on the occulusive surface and the buccal surface of the retaining knobs set on the buccal side and the lingual side.
4. The fitness of the bridge was almost the same as in the case of the investing method, and further the time taken for technical operation was largely shortened. Therefore, it has been shown that this method is extremely useful for clinical application.
