Abstract
Statement of problem
Selective laser melting (SLM) technology has been introduced for printing metal dental
restorations from Co-Cr base alloys or Au-Pt high noble alloys. However, information
regarding the fit of restorations fabricated by using this technique is limited.
Purpose
The purpose of this in vitro study was to determine the effect of 3 different finish
line designs on the marginal and internal gaps of metal copings made from a base (Co-Cr),
high noble (Au-Pd-Ag), and noble alloy (Co-Pd) by using the SLM technology.
Material and methods
Three Ivorine right maxillary central incisors were prepared with a chamfer, deep
chamfer, or shoulder finish line. The preparations were scanned by using a TRIOS scanner,
and a total of 90 dies were printed using DPR 10 Resin (30×3 finish line designs).
Ten SLM copings were fabricated for each margin design and metal alloy combination
for a total of 90 copings (10×3 finish line designs×3 alloys). Copings were cemented
onto dies using an autopolymerizing composite-resin luting material. All coping-die
assemblies were sectioned buccolingually by using a low-speed diamond saw, and images
were obtained by using an inverted bright field metallurgical microscope at ×100 magnification.
Marginal and internal gaps were measured at 5 locations: buccal margin, midfacial,
incisal, midlingual, and lingual margin. After gap measurements, representative specimens
were embedded in autopolymerizing resin and prepared for metallographic examination.
A 2-way multivariate analysis of variance (MANOVA) was conducted to determine the
overall significance, followed by ANOVA for each dependent variable (α=.05).
Results
The results indicated that alloy type and finish line had a significant influence
on marginal gap of copings (P<.001). Relative to the internal gap, alloy type had a significant effect (P<.001), but the type of finish line had no statistically significant influence (P=.337). No statistically significant interactions occurred. Base alloys were printed
with almost no observable porosity, whereas noble and high noble alloys exhibited
hot tears and porosity.
Conclusions
Thefinish line type did not influence the internal gap between copings and dies, whereas
the alloy type influenced the marginal gap between copings and dies. SLM-fabricated
Co-Cr copings on teeth prepared with a deep chamfer finish line demonstrated the lowest
marginal gap.
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Article info
Publication history
Published online: April 01, 2019
Footnotes
The investigators wish to thank the American Academy of Fixed Prosthodontics for their support with a Dr Stanley Tylman Research Grant.
Identification
Copyright
© 2019 by the Editorial Council for The Journal of Prosthetic Dentistry.
