Time-related wettability characteristic of acrylic resin surfaces treated by glow discharge

Statement of problem. Adhesion and cohesion have important roles in denture retention, and attempts have been made to improve the wettability of the a crylic resin material by surface treatments. Purpose. This study examined the initial and subsequent wettability of an a crylic resin denture base material treated under air or argon plasma atmosp here before and after exposure to air or distilled water. Material and methods. Acrylic resin specimens were treated with plasma unde r air or argon atmosphere and were either exposed to air or distilled water for up to 60 days. Wettability characteristics of the acrylic resin specim ens were determined by contact-angle measurements after 2 hours and after 6 0 days. Surface composition of the specimens also was analyzed with x-ray p hotoelectron spectroscopic (XPS) measurements. Results. Statistically significant difference was found between control and each of the plasma treatment groups (P<.05). Although the storage conditio n and storage period caused statistically significant difference on contact angle values (P<.05), atmosphere type did not have any effect on the resul ts (P>.05). XPS spectra of the plasma-treated specimens differed from contr ol specimens only in the Ols region with a narrower and more intense peak t hat could be assigned to -COH groups. During 60 days of exposure, the O/C a tomic ratios decreased within the first 2 weeks but settled to 0.40 and 0.3 2 up to 60 days compared with 0.26 for untreated control specimens. Conclusion. Glow discharge plasma altered the surfaces of the acrylic resin and increased the wettability as shown both by XPS and contact-angle measu rements, and plasma treatment seemed to offer a durable (at least up to 60 days) wettability.