Abstract
Among the various factors that affect the fitness of the soldering bridge, The electrical tacking method has taken into the three dimensional distortions of retainers were measured.
In conducting these studies, the author assembled three units fixed bridge with the second premolar and molar were as abutments and the first molar as a pontic on the mandible.
Following conclusions were obtained as a result.
1. During the electrical tacking stage, the retainers were displaced about 10 microns in each directions.(X, Y, Z)
2. At the soldering stage the liner distortion of retainers were paticulary larger in mesiodistaly.(ΔX)
The fixed bridge become about 25 microns shorter as the result of the distortion.
3. When compared the electrical tacking method and the invest method, electrical tacking method was about three times greater on the mesio-distal distortion, and two times greateron the vector distortion than the invest method.
4. In the case of the electrical tacking method was applied, the liner distortions were greater than the other rotational distortions caused by the complicate movement during the soldering stage on the retainers and pontic.
