Document Type : Original Articles

Abstract

Introduction: Although soldering has been widely used in prosthodontics during recent decades, effects of soldering on bond strength between porcelain and metal has not been studied extensively so far. The purpose of this study was to evaluate fracture resistance of porcelain to soldered and non-soldered joints in fixed partial dentures. Materials and Methods: a total of 22 metal substructures for 3 units of metal ceramic bridges were made under similar conditions. Samples were divided into two groups (n=11). In one group, samples were cut in the middle of the pontic and were soldered. Porcelain was applied on all samples. The fracture resistance in the middle of pontic was tested using universal testing machine at a cross head speed of 1 mm/min until bond failure between porcelain and metal occurred. The average force needed for debonding in each sample was measured. The collected results were then analyzed through T paired-test on a computer using SPSS11.5 (α = 0.05). Results: Average forces required for breaking the bond between porcelain and metal in soldered and non- soldered samples were 687.87  ±62.3 N and  621.14 ± 80.8 N respectively. This difference was statistically significant (P=0.042). Conclusion: Within considering the limitation of this study, soldering seems to increase bond strength between metal and porcelain. Since there have been few studies on this subject so far, it is recommended to more research would be planned on this subject, especially with respect to the effect of alloy type, soldering method and the mechanism of force exerted on bond between porcelain and metal.   Key words: Bond strength, Soldered joints, Porcelain, Fixed partial dentures.