Abstract
Statement of problem
Additive manufacturing by selective laser melting (SLM) has been claimed to be less
challenging than conventional casting of cobalt-chromium (Co-Cr) removable partial
dentures (RPDs), providing significant improvements. However, how the physicomechanical
properties of Co-Cr RPDs fabricated by SLM compare with those fabricated by conventional
casting is unclear.
Purpose
The purpose of this in vitro study was to evaluate the physicomechanical properties
of Co-Cr RPD palatal major connectors fabricated by SLM compared with those fabricated
by conventional casting.
Material and methods
A master die simulating a maxillary arch of Kennedy class III modification 1 was scanned
to create a virtual 3-dimensional (3D) cast. Two groups of 5 Co-Cr RPD major connectors
were fabricated. In the 3D printing group, the Co-Cr major connector was virtually
designed and exported for direct SLM 3D printing. For the conventional group, Co-Cr
major connectors were constructed conventionally. The Co-Cr major connectors were
virtually superimposed with the master die for surface adaptation analysis. Additional
comparative analyses of surface roughness, relative density, microhardness, and microstructure
of the 2 groups were performed. Data were analyzed by using independent t tests (α=.05).
Results
The overall volumetric and linear discrepancies were significantly higher (P<.05) in the 3D printing group. Significant differences in the surface roughness (P<.05) and microhardness (P<.05) were observed, with the 3D printing group having higher surface roughness and
microhardness than the conventional group. Unlike conventional connectors, the microstructure
of 3D-printed connectors showed fine homogeneous granules.
Conclusions
Compared with the conventional casting technique, SLM 3D printing enabled the fabrication
of Co-Cr RPD major connectors with higher microhardness and fine homogenous microstructure.
However, the surface adaptation and surface roughness of SLM 3D printing Co-Cr connectors
were worse than those produced conventionally. Both techniques showed similar relative
densities.
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Article info
Publication history
Published online: August 03, 2022
Footnotes
Supported by the Faculty of Dentistry, University of Malaya funded by Faculty Research Grant GPF013E-2018.
Identification
Copyright
© 2022 by the Editorial Council for the Journal of Prosthetic Dentistry.
