The effect of denture cleansers on the mechanical and optical properties of 3D printed and heat-polymerized dentures
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Citation
Abstract
OBJECTIVE: To assess the effect of denture cleansers on the mechanical and optical
properties such as color stability, surface hardness, surface roughness, and flexural strength
of the 3D printed denture acrylics in comparison to heat polymerized denture acrylics.
MATERIALS AND METHODS: A total of 216 disc specimens (12 mm × 2mm) were made from
Lucitone Digital Print, DENTCA Denture Base II, Formlabs denture resin, and Lucitone
199. Each type of acrylic was divided into four sub-groups, Efferdent, Polident, dish soap
and control group in water. Specimens of each material were exposed to a total of 28 cycles
of immersion in denture cleanser, while being stored in water in an incubator at 37°C in
between cycles to test for color stability, surface roughness, microhardness and biaxial
flexural strength. Baseline values were obtained for color, hardness, surface roughness, and
biaxial flexural strength using a CIE L*a*b* color space by spectrophotometer, Vickers
microhardness in hardness tester, line Ra by profilometer, and ball-on-three-ball fixture
with universal testing machine respectively. Color, surface roughness, and surface
hardness values were obtained at the 8th, 16th, and 28th cycles in order to compare color stability along with changes in surface roughness and surface hardness. Biaxial flexural
strength values were performed for specimens at the 28th cycle as a destructive test to
compare values of treated and untreated specimens. SEM analysis was performed to assess
fracture behavior and microstructural changes. The differences between the tested
materials and the treatment effects were statistically analyzed using the Tukey HSD test
(a=0.05) and MANOVA test (a=0.05)
RESULTS: The greatest significant change in color was seen in Lucitone 199 specimens (P
value <0.0001) when exposed to dish soap. Lucitone 199 and Lucitone Digital Print had
the significantly lowest microhardness values (P value< 0.0001) after exposure to
treatments, especially dish soap. Surface roughness was significantly higher for all 3D
specimens initially (P value <0.001), however with exposure to Efferdent and Polident,
Lucitone 199 specimens had the greatest significant increase in surface roughness. The
surface roughness of 3D printed specimens did not significantly increase with exposure to
treatments. The biaxial flexural strength of all materials decreased significantly with the
exposure to all treatments (P value< 0.0001). Overall, Lucitone 199 had the lowest flexural
strength in both treatment and control groups compared to all the 3D printed materials.
Formlabs was significantly affected by exposure to treatments,and had the greatest
decrease in biaxial flexural strength (P value <0.0001).
CONCLUSION: Within the limitations of this study, we can conclude that 3D printed materials
in this study are more color stable that the heat-polymerized Lucitone 199. In regards to
microhardness, 3D printed materials except for Lucitone Digital Print have higher
microhardness values than heat-polymerized materials. Although Lucitone 199 had a smoother surface as prepared, the 3D printed materials in this study maintained their
roughness values throughout the study, whereas Lucitone 199 showed a significant
increase in roughness. The properties of 3D printed materials show a promising future for
their use in treating edentulous patients. Although there are limitations to this study, it is
safe to say that denture cleansers are safe to use with 3D printed dentures as long as the
manufacturer’s instructions are correctly followed.