Simplified Acid Treatment Technique in Cobalt-Chromium Alloys: Effect on Metal-Ceramic Bond Strength

This study aim was to evaluate the influence of 37% hydrochloric acid (37% HCl) treatment of cobalt-chromium (Co-Cr) alloys on the metal-ceramic bond strength (MCBS). The specimens were sandblasted with 100-µm aluminum oxide particles and divided into four groups (n = 10) according to the surface treatment performed: control (C) - no treatment - and treated with 37% HCl for different times: 10 minutes (T1), 20 minutes (T2) and 30 minutes (T3). The samples were submitted to the 3-point bending test, and the type of failure was evaluated. Wald, Bonferroni and Pearson's tests were applied (α = 0.05). There was difference between the treatments (p = 0.019): T3 (61.57 MPa) had higher bond strength than C (51.96 MPa). The specimens presented 17.5% of adhesive and 82.5% of mixed failures. There was a weak correlation between the failure type and the MCBS. Co-Cr surface treatment with 37% HCl for 30 minutes is a promising protocol for an appropriate metal-ceramic bond strength.