Base metal, Bond strength, Ceramic, Energy-dispersive X-ray, Scanning electron microscope
Citation Information :
Pahwa R, Dureja I, Pahwa A, Gupta A, Yadav B. Evaluation of the Effect of Varying Percentage of Recast Metal–Ceramic Alloy on Bond-strength and Oxide-layer Composition using SEM and EDX: An In Vitro Study. Int J Prosthodont Restor Dent 2023; 13 (3):154-162.
Purpose: An in vitro study to evaluate and compare the bond strength of veneered porcelain as affected by the addition of recast nickel-chromium alloy in varying percentages using the universal testing machine (UTM) and to analyze the oxide layer on the metal specimens using the scanning electron microscope (SEM) and energy-dispersive X-ray (EDX).
Materials and methods: Forty disk specimens of dimension 8 × 2 mm were fabricated from Bellabond Plus alloy (Bego, Germany) using recast metal in different (n = 10 samples/group) (group I: 100% fresh metal; group IIA: 75% fresh metal and 25% recast metal; group IIB: 50% fresh metal and 50% recast metal; and group IIC: 25% fresh metal and 75% recast metal). Application of commercially available porcelain (Ceramco 3) was done up to a thickness of 2 mm. Samples were then placed under SEM for EDX examination to evaluate ionic changes that occurred at the metal–ceramic interface. Bond strength of each sample was evaluated under UTM. The statistical analysis was done using one-way analysis of variance (ANOVA) test and post hoc test.
Results: The one-way ANOVA showed that for the oxide layer content, a significant difference was seen in the values of chromium, nickel, and oxygen (p < 0.001). As the content of recast metal in sample increases, there is a significant decrease in the bond strength value, thus making the metal−ceramic bond weaker (p < 0.001). On performing the Tukey honestly significant difference (HSD) test, values were significant for nickel, chromium, and oxygen in the oxide layer content among different groups of new and recasted metal alloys (p < 0.05) and were not significant for silica, aluminum, and sulfur (p > 0.05).
Conclusion: As the content of recasted metal increases, there is a decrease in the bond strength and increase in oxygen content in oxide layer. An adequate bond strength of 40 MPa was not achieved if the recasted metal is >50%. Thus, the data revealed that we could use up to 50% of recasted metal for prosthesis fabrication; beyond this limit, the bond strength is not adequate for dental use.
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