Statement of problem
Rough surfaces of denture bases promote adhesion of microorganisms and plaque formation.
It is therefore important to know how different polishing systems affect surface roughness
of denture base acrylic resins.
The objective of this study was to compare the effects of 4 chairside polishing kits
and 2 conventional laboratory techniques used for polishing 3 different acrylic denture
Material and methods
Using contact profilometric measurement, the surface texture of 54 specimens (15 ×
30 × 3 mm) per acrylic material (autopolymerized ProBase Cold, heat-polymerized ProBase
Hot, and injection heat-polymerized SR Ivocap plus) was studied before and after cutting
with a tungsten carbide bur, and during and after chairside polishing with 4 polishing
kits (Exa Technique, Acrylic Polisher HP blue, AcryPoint, Becht Polishing Cream),
and after conventional polishing with 2 polishing systems (Universal Polishing Paste
for Resins and Metals, Lesk Polishing Liquid). There were 9 specimens for each acrylic
resin material and polishing method combination. Conventional lathe polishing with
polishing paste served as the control. Mean average surface roughness (Ra) values of each specimen group were analyzed using a 2-way analysis of variance,
the Scheffé post-hoc test, and paired t test (α=.05) with the Bonferroni adjustment. After testing the polished acrylic resin
surfaces were evaluated under a scanning electron microscope.
The highest mean average surface roughness (Ra = 2.86 ± 0.8 μm to 3.99 ± 1.31 μm) was measured for surfaces finished with a tungsten
carbide bur. The lowest surface roughness values (Ra = 0.02 ± 0.01 μm) were determined for acrylic resin specimens polished with a lathe
and polishing paste. The Ra values of resin specimens after polishing with chairside silicone polishing kits
ranged from 0.05 ± 0.0 μm to 0.35 ± 0.05 μm. Mean average Ra values of specimens polished with a polishing cream alone (Ra = 1.01 ± 0.17 μm to 1.68 ± 0.47 μm) were significantly higher (P<.05) than those obtained with other polishing systems tested, which was confirmed
by scanning electron microscope images of acrylic resin surfaces. Significant differences
in mean average surface roughness were found between autopolymerizing and injected
heat-polymerizing resin specimens. In addition, scanning electron microscopy revealed
increased porosity of autopolymerizing resin specimens.
Conventional laboratory polishing was found to produce the smoothest surface of denture
base acrylic resin. Chairside silicone polishing kits produced a significantly smoother
surface of acrylic resin than specimens polished with a tungsten carbide bur. The
presence of large pores was characteristic for the autopolymerizing resin material.