Effect of Recycling Cobalt-Chromium Alloy Powder on Metal- Ceramic Bond Strength and Microstructure.

Abstract

Purpose: This in vitro study is of significant importance as it examines the effects of reusing cobalt-chromium-tungsten-containing alloy powder on metal-ceramic bond strength and microstructure, providing valuable insights into the field of dental materials.

Materials and methods: Thirty bar and nine square-shaped cobalt-chromium frameworks were produced by the conventional lost wax (Group C, [nBar=10, nSquare=3]) and selective laser melting technique (virgin powder, Group V [nBar=10, nSquare=3]; 25-times reused powder, Group R [nBar=10, nSquare=3]). X-ray diffraction, scanning electron microscopy, and ONH analysis were used to evaluate the casting ingot, powders, and frameworks' phase compositions, grain size, and microstructure. Three-point bend tests were used to assess the metal-ceramic bond strengths. Metal-ceramic bond strength values were compared using a one-way analysis of variance.

Results: The bond strengths did not show significant differences (P>.05) between Groups C (29.95 ±4.60), V (31.32 ±3.44), and R (29.90 ±5.50). The recycled alloy powder's grain size (14.1 ±6.33 µm) was more significant than that of the virgin alloy powder (12.24 ±6.03 µm). Twenty-five times reused alloy powder had a greater N concentration than virgin powder. Group V and R had similar X-ray diffraction patterns, but the Group R frameworks had porous microstructure.

Conclusion: Reusing cobalt-chromium alloy powder 25 times did not affect the metal-ceramic bond strength. Recycling the cobalt-chromium alloy powder is advisable.