The effects of current production techniques on the surface roughness, oxide layer thickness and porcelain bond strength of cobalt-chromium and titanium substructures

Ünalan Değirmenci B., Ersoy N. M.

International Dental Reseach, vol.11, no.3, pp.1-11, 2021 (Peer-Reviewed Journal)


Aim: This study aimed to evaluate the oxide layer, surface roughness, and bond strength with porcelain of cobalt-chromium (Co-Cr) and titanium (Ti) substructures produced using casting, milling and selective laser sintering techniques.

Methodology: A total of 180 disc-shaped metal samples with a diameter of 1 cm and a thickness of 3 mm were produced. The samples were divided into six groups (n=15) according to the technique used to produce the metal substructurescasting, milling, and SLSand the chemical composition of the metal substructureCo-Cr and Ti. Then roughness averages (Ra) of the sample surfaced were calculated with a contact-type profilometer. Nondestructive energy-dispersive X-ray was performed to ensure that the layer displayed in contrast was the oxide layer, and the average oxide layer thickness was calculated from scanning electron microscope images. Metal-porcelain complexes were subjected to shear bond strength test and failure types were noted. Two-way multivariate analysis of variance (MANOVA) was used to compare oxide layer thickness, surface roughness, and shear bond strength according to the metal and production technique, and Tukey’s honestly significant difference (HSD) test was used for multiple comparisons of the main effects.

Results: Two-way MANOVA revealed that the metal and technique used in the substructure production had significant effects on surface roughness, oxide layer thickness and shear bond strength (p < 0.001). Ti groups exhibited thicker oxide layer formation than Co-Cr groups. Low surface roughness values were observed in the milling groups. The highest shear bond strength value (53.8 MPa) was observed in the Co-Cr group produced by casting, while the lowest value (32.2 MPa) was obtained in the Ti group produced by casting.

Conclusion: It should be kept in mind that there is no ideal production technique and that the effects of the production technique differ depending on the metal used.