In vitro comparative study of the surface properties of materials for removable prosthetic bases

Objectives: This work aimed to evaluate and compare the surface roughness, contact angle, and C. albicans adhesion in three materials for removable denture bases: polymethylmethacrylate and the thermoplastic resins polypropylene and polyolefin. Methods: Nine samples were manufactured, three of each material (n=3): polypropylene, polyolefin, and polymethylmethacrylate (control group). The thermoplastic resins were fabricated by injection technique and the polymethylmethacrylate by compression technique. After laboratory polishing, the surface roughness (Ra and Rz) was assessed with the 3D optical roughness meter NPFLEX, and the contact angle was measured with the optical tensiometer Contact angle system OCA15. C. albicans adhesion was assessed through colony- forming unit assays (n=9). ANOVA and Kruskal-Wallis tests were done to compare groups, considering a significance level of 0.05. Results: All values obtained for the control group were lower than those obtained for the thermoplastic resins. Statistically significant differences were found: for Ra between polypropylene (0.15±0.072 μm) and polymethylmethacrylate (0.03±0.006 μm) (p=0.045); for the contact angle between the three groups (p<0.001) – polymethylmethacrylate (26.57±6.719°), polypropylene (57.57±11.098°), and polyolefin (69.06±8.955°); and for C. albicans adhesion between polymethylmethacrylate and polypropylene (p=0.007) and polymethylmethacrylate and polyolefin (p=0.013). Conclusions: In the tested conditions and for the materials assessed, polymethylmethacrylate showed the lowest roughness, contact angle, and C. albicans adhesion, thus exhibiting better properties for removable denture bases than the thermoplastic materials.