Stainability of acrylic resin materials used in CAD-CAM and conventional complete dentures
The Journal of Prosthetic Dentistry
Available online 5 November 2019
Abstract
Statement of problem
The
effect of staining beverages on the color of dentures made with
computer-aided design and computer-aided manufacturing (CAD-CAM) is
unknown.
Purpose
The
purpose of this in vitro study was to evaluate the stainability of
acrylic resins used in CAD-CAM–fabricated complete dentures compared
with conventional materials.
Material and methods
Acrylic
resin denture teeth from 3 different manufacturers (2 conventional and 1
milled) were obtained (N=45). Denture base acrylic resin specimens were
made with 3 different techniques (compression molding, injection
molding, and milling) (N=45). Conventional and/or milled acrylic resins
were used to make specimens comprising both denture teeth and denture
base acrylic resins (4 conventional, 2 milled denture bases with bonded
teeth, and 1 all-milled) (N=105). All specimens were then immersed in
coffee, red wine, or distilled water as control. The CIELab color
differences between before and after immersion were determined by using a
VITA Easyshade spectrophotometer. The tooth-denture base interface of
the denture blocks was evaluated visually for the presence of stain. The
CIELab data were analyzed by using ANOVA, and chi-square test was used
for visual assessment (α=.05).
Results
Significant
interactions were found between each acrylic resin material and each
staining solution immersion when compared with distilled water immersion
(P<.001). Denture teeth had similar color change after immersion in coffee (P=.149), while the most pronounced color change was observed with Portrait teeth upon immersion in wine (P<.001).
Injection-molded denture base specimens exhibited less color change
upon staining in wine than compression-molded or milled specimens (P<.001). Upon staining in coffee, milled specimens were not significantly different from injection- (P=.053) and compression-molded specimens (P=.180).
The chi-square test showed a significant association between processing
technique and stain accumulation at the tooth-denture base interface
when evaluated visually (P<.001). Stain accumulation was
greatest with compression-molded specimens (58%), followed by
injection-molded (43%) and milled specimens with bonded teeth (8%).
Monolithic teeth with milled denture base had no stain deposits at the
tooth-denture base interface.
Conclusions
The
stainability of milled acrylic resins was no better than that of
conventional materials. However, CAD-CAM milled denture blocks with
teeth and base acrylic resins had greater resistance to stain
accumulation at the tooth-denture base interface than those of
conventional processing methods.
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