Purpose: This study was conducted to measure and compare the effect of the soldering method (torch soldering or ceramic furnace soldering) used for soldering bars to bar-retained, implant-supported overdentures on the fit between the bar gold cylinder and implant transgingival abutment.
Materials and methods: Thirty-two overdenture implant bars were manufactured and screw retained into two Bränemark implants, which were attached to a cow rib. The bars were randomly distributed in two groups: a torch-soldering group and a porcelain-furnace soldering group. Then all bars were cut and soldered using a torch and a ceramic furnace. The fit between the bar gold cylinders and implant transgingival abutments was measured with a light microscope on the opposite side to the screw tightening side before and after the bar soldering procedure. The data obtained were statistically processed for paired and independent data.
Results: The average misfit for all bars before soldering was 33.83 to 54.04 μm. After cutting and soldering the bars, the misfit increased up to a range of 71.74 to 78.79 μm. Both before and after the soldering procedure, the bars soldered using a torch showed a higher misfit when compared to the bars soldered using a porcelain furnace. After the soldering procedure, the misfit was slightly lower on the left side of the bars, which had been soldered using a ceramic furnace.
Conclusions: According to our data, the soldering of bars using the torch or furnace oven soldering techniques does not improve the misfit of one-piece cast bars on two implants. The lower misfit was obtained using the porcelain furnace soldering technique.
Keywords: Misfit; ceramic furnace; light microscope; torch; welding.
© 2013 by the American College of Prosthodontists.