Abstract
Statement of problem
Direct metal laser sintering (DMLS) and direct metal laser melting (DMLM) have become
popular for fabricating the metal frameworks of metal-ceramic restorations. How the
type of layered manufacturing device, layer thickness, and alloy powder may affect
the bond strength of ceramic to metal substructure is unclear.
Purpose
The purpose of this in vitro study was to evaluate the bond strength of dental porcelain
to metal frameworks fabricated using different layered manufacturing techniques (DMLS
and DMLM), Co-Cr alloy powders, and layer thicknesses and to evaluate whether a correlation
exists between the bond strength and the number of ceramic remnants on the metal surface.
Material and methods
A total of 75 bar-shaped metal specimens (n=15) were fabricated using either DMLS
or DMLM. The powder alloys used were Keramit NP-S and EOS-Cobalt-Chrome SP-2 with
layer thicknesses of 20 μm and 30 μm. After ceramic application, the metal-ceramic
bond strength was evaluated with a 3-point-bend test. Three-way ANOVA followed by
the Tukey honest significance difference test were used for statistical analysis (α=.05).
De-bonding surface microstructure was observed with scanning electron microscopy.
Energy dispersive spectroscopy analysis was conducted to evaluate the correlation
between ceramic remnants on the metal surface and bond strength values.
Results
The mean bond strength value of DMLS was significantly higher than that of DMLM. While
no statistically significant difference was found between layer thicknesses, alloy
powders closely affected bond strength. Statistical comparisons revealed that the
highest bond strength could be achieved with DMLS-Cobalt-Chrome SP2-20μm, and the
lowest bond strength was observed in DMLS-Keramit NP-S-20μm (P≤.05). No correlation was found between porcelain remnants on the metal surface and
bond strength values.
Conclusions
The layered manufacturing device and the alloy powders evaluated in the current study
closely affected the bond strength of dental porcelain to a metal framework. However,
layer thickness did not affect the bond strength.
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Article info
Publication history
Published online: July 06, 2017
Footnotes
Supported by Scientific Research Projects Coordination Unit of Cukurova University, project no. TSA-2016-5515.
Identification
Copyright
© 2017 by the Editorial Council for The Journal of Prosthetic Dentistry.
