Abstract
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.
Highlights
Metal-ceramic restorations have acceptable clinical performance, longevity[1], and physical properties[2]
The composition and morphology of this oxide layer depends on the type of surface treatment performed[14] as well as interaction among atoms from both metal and ceramic[12], which may interfere in MCBS13-15
This study aimed to investigate the effect of Cobalt-chromium alloys (Co-Cr) alloy surface treatment with 37% hydrochloric acid (37% HCl) for different exposure times on the metal-ceramic bond strength (MCBS)
Summary
Metal-ceramic restorations have acceptable clinical performance, longevity[1], and physical properties[2]. Their clinical success depends on a number of factors, including the properties of the alloy[2], adequate marginal fit, and adequate metal-ceramic bond strength[3]. Chemical bond occurs when the elements of dental alloys, such as cobalt, chromium, and molybdenum[13], undergo surface oxidation forming ion channels, where the diffusion of atoms present in metal-ceramic interface occurs[13]. The composition and morphology of this oxide layer depends on the type of surface treatment performed[14] as well as interaction among atoms from both metal and ceramic[12], which may interfere in MCBS13-15. If the layer formed of Cr2O3 is compact[16], there is reduced bond strength on this
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