Abstract
Objectives This study aimed to examine the wear on opposing enamel caused by additive manufacturing
techniques for cobalt-chromium (Co-Cr) alloys. Selective laser melting (SLM) techniques
were compared with conventional methods. Cast nickel-chromium (Ni-Cr) alloys were
also included for comparison.
Materials and Methods Four groups of dental alloys were examined (n = 10/group): as-built SLM Co-Cr (CS), heat-treated SLM Co-Cr (CS-H), cast Co-Cr (CC),
and cast Ni-Cr (NC) alloys. Surface roughness and hardness of these alloys were initially
assessed. Wear test was conducted against human enamel cusps using a chewing simulator
(49-N load, 1.6-Hz frequency). Volumetric and vertical enamel wear were measured at
60,000, 120,000, and 240,000 chewing cycles using an intraoral scanner combined with
open-source 3D software.
Statistical Analysis Enamel wear was analyzed using a generalized estimating equation (α = 0.05).
Results Alloy hardness varied among the groups. NC exhibited the lowest hardness, followed
by CS, CC, and CS-H. Throughout the entire test, no significant differences in enamel
wear were observed among CS, CS-H, and CC. However, NC caused lower enamel wear than
the other groups, with a more pronounced difference observed after 120,000 chewing
cycles.
Conclusion SLM is a promising alternative for manufacturing Co-Cr alloys used in fixed dental
prostheses, as it exhibited comparable enamel wear to conventional casting. Moreover,
optimized heat treatment enhanced the hardness of SLM-fabricated alloys without increasing
enamel wear. However, it is noteworthy that Co-Cr alloys fabricated by any techniques
resulted in higher enamel wear than Ni-Cr alloys.
Keywords
casting technique - cobalt-chromium alloys - fixed indirect restoration - selective
laser melting - tooth wear
