Comparative tensile strengths of preceramic and postceramic solder connectors using high-palladium alloy

Statement of problem

It is not known whether different high-palladium alloys of similar composition possess comparable tensile strength properties associated with connector soldering.

Purpose

The purpose of this study was to evaluate the tensile strength properties of 2 high-palladium alloys on soldered connectors under simulated pre-ceramic and post-ceramic soldering conditions.

Material and methods

Eighty cylindrical castings were fabricated (Rx Naturelle Plus alloy and Option alloy). The 40 castings for each alloy were subdivided into 2 groups of 20 each. In the first group, castings for each alloy were randomly paired and soldered with presolder (SMG2) to produce 10 preceramic test connector specimens for each alloy. In the second group, castings were similarly paired and soldered with postsolder (490 fine) to produce 10 postceramic test connector specimens for each alloy. Each soldered connector was subjected to tensile force until failure in a universal testing machine. Statistical analysis using a Wilcoxon rank sums test was performed (α=.05)

Results

No significant difference was found between the mean tensile failure stress for Rx Naturelle Plus preceramic solder (344.7 ± 77.6 MPa) compared to Option preceramic solder (411.5 ± 112.8 MPa) (P=.1202). However, the mean tensile failure stress for Rx Naturelle Plus postceramic solder (260.8 ± 223.7 MPa) was significantly lower than the Option postceramic solder (312.6 ± 120.8 MPa) (P=.0407). Not only did Rx Naturelle Plus postceramic solder connectors show evidence of lower strength, but also an increased variation among specimens.

Conclusions

Rx Naturelle Plus solder connectors provided better strength with the preceramic as opposed with the postceramic connectors. For postsolder connectors, Rx Naturelle Plus alloy had less acceptable strength and a wider variation, suggesting it is more technique sensitive than Option alloy connectors.