Correlation between metal-ceramic bond strength and coefficient of linear thermal expansion difference

Abstract

The purpose of this study was to evaluate the metal-ceramic bond strength (MCBS) of 6 metal-ceramic pairs (2 Ni-Cr alloys and 1 Pd-Ag alloy with 2 dental ceramics) and correlate the MCBS values with the differences between the coefficients of linear thermal expansion (CTEs) of the metals and ceramics. Verabond (VB) Ni-Cr-Be alloy, Verabond II (VB2), Ni-Cr alloy, Pors-on 4 (P), Pd-Ag alloy, and IPS (I) and Duceram (D) ceramics were used for the MCBS test and dilatometric test. Forty-eight ceramic rings were built around metallic rods (3.0 mm in diameter and 70.0 mm in length) made from the evaluated alloys. The rods were subsequently embedded in gypsum cast in order to perform a tensile load test, which enabled calculating the CMBS. Five specimens (2.0 mm in diameter and 12.0 mm in length) of each material were made for the dilatometric test. The chromel-alumel thermocouple required for the test was welded into the metal test specimens and inserted into the ceramics. ANOVA and Tukey's test revealed significant differences (p=0.01) for the MCBS test results (MPa), with PI showing higher MCBS (67.72) than the other pairs, which did not present any significant differences. The CTE (10-6 °C-1) differences were: VBI (0.54), VBD (1.33), VB2I (-0.14), VB2D (0.63), PI (1.84) and PD (2.62). Pearson's correlation test (r=0.17) was performed to evaluate of correlation between MCBS and CTE differences. Within the limitations of this study and based on the obtained results, there was no correlation between MCBS and CTE differences for the evaluated metal-ceramic pairs.

Nickel-Containing Alloys for Medical Application Obtained by Methods of Mechanochemistry and Powder Metallurgy

“…Among these properties the value of the linear coefficient of thermal expansion (CTE) is decisive for the compatibility between the ceramic veneer and metal construction. In order to produce compressive stress in the porcelain during cooling there is a general consensus that the alloy should have higher CTE than the porcelain [9][10][11]. The value of 13.9 × 10 −6 × C −1 in the temperature interval 25-600 • C was determined by dilatometric tests and is similar to the data for most of the market available Ni-based dental alloys.…”

Effect of different air-abrasion particles on metal-ceramic bond strength

“…Some authors stated that there is no methodology capable of measuring only shear forces along the metal-porcelain interface. 2,20,21 Hammad and Talic 20 carried out a critical analysis of tests used for metal-ceramic systems. These authors stated that shear tests with a flat interface mostly direct the tension to the interface and does not evaluate the elasticity modulus of the metal as in flexural tests.…”

“…Base-metal alloys are economical alternatives to expensive gold alloys. 2 These alloys allow the fabrication of thinner infrastructures because they have greater rigidity, which is related to the modulus of elasticity. Nickel-chromium (Ni-Cr) and cobalt-chromium (Co-Cr) alloys are the most widely used when cost and rigidity are considered.…”

Effect of casting atmosphere on the shear bond strength of a ceramic to Ni-Cr and Ni-Cr-Be alloys

“…It is possible that the use of the induction casting technique, in which there was always the alloy protection may have contributed to the homogeneity in the results observed for different combinations. In addition, in this experiment, any pre-heating treatment of the alloys was not performed aiming at to minimize the effect of the chemical interaction among the evaluated materials (17). According to a previous study (14), the presence of Al (as Al 2 O 3 ) and Be (as BeO) on the oxide layer of Ni-Cr alloy specimens subjected to pre-heating resulted in a better metal-ceramic bonding behavior.…”