The effect of thermal cycling on metal-ceramic bond strength

Objectives: The aim was to evaluate the effect of thermal cycling on the metal-ceramic bond strength. Methods: Four different noble metal alloys were used. Specimens for the crack initiation test according to ISO 9693 were prepared to assess metal-ceramic bond strength (n = 10). The metal substrates were either air-borne particle abraded or polished prior to veneering. Bond strength was measured after veneering or after 6000 thermal cycles. With one alloy in addition long-term thermal cycling with 15,000 and 50,000 cycles was carried out. Statistical analysis was performed with one-way ANOVA followed by a post hoc Bonferroni test. Results: Polished metal substrates showed a significantly lower bond strength compared to the air-borne particle abraded substrates. Treatment with 6000 thermal cycles did not significantly reduce the bond strength. Long-term thermal cycling resulted in an exponential decrease of bond strength for both polished and air-borne particle abraded specimens. Conclusions: Air-borne particle abrasion significantly increases metal-ceramic bond strength. Thermal cycling of metal-ceramic composites results in an exponential decrease of bond strength. The crack initiation test is a sensitive method for assessing the metal-ceramic bond strength. (C) 2009 Elsevier Ltd. All rights reserved.