Effect of soldering on bond strength of porcelain to metal in porcelain-fused-to-metal castings

Soldering has several applications in prosthodontic treatments; however, the effect of soldering on porcelain to metal bond strength has not been adequately studied. This study was designed to assess the bond strength of porcelain to metal, and the mode of failure at the soldered and non-soldered areas of cubic specimens.

In this in vitro, experimental study, 40 porcelain-metal specimens were fabricated under similar conditions and divided into two groups (n=20). In the test group, a hole was created at the center of the frame and was then soldered and veneered with porcelain. The second group was considered as a control group. The bond strength was measured at the center of the specimen using the 3-point bending test in a universal testing machine with a crosshead speed of 0.5 mm/min. The mean force required for debonding was determined. Photographs of the specimens were digitalized by a scanner and magnified on a computer screen with x10.5 magnification. Next, each image was divided into 100 squares (1×1 mm). The mode of failure was determined for each specimen. The two groups were compared using independent t-test (p-value˂ 0.05).

The mean porcelain-metal bond strength was 36.6±7.3 N for the soldered and 37.4±4.6 N for the non-soldered group with no significant difference between them (P>0.05). The mode of failure was cohesive in all specimens in both groups with no significant difference between them (P>0.05).

Within the limitations of this study, the soldered and non-soldered specimens showed no significant difference regarding the porcelain-metal bond strength.