Coating of silicone-based impression materials in a glow-discharge system by acrylic acid plasma

Objectives. The main purpose of this study was to demonstrate an increase in the wettability of silicone-based impression materials after coating them with a hydrophilic film in a glow-discharge system. Methods. Two vinyl polysiloxane impression materials, Extrude (Kerr) and Accuflex (GC America Inc.) were used. Impression specimens were treated in a glow-discharge reactor at a radio frequency of 13.56 MHz at different discharge powers (5–20 W) and exposure times (5–60 min). Surface analysis of the specimens was done by FTIR. Surface contact angles were obtained by a captive-bubble method. These results were analyzed by ANOVA and Duncanʹs Multiple Range test (p < 0.05). The total number of voids on the die stone casts was observed microscopically. Linear dimensional accuracy, detail reproducibility, and surface hardness of the die stone casts were also determined. A Student t-test was performed for statistical analysis of these parameters (p > 0.05). Results. FTIR spectra indicated that the number of hydroxyl groups on the surfaces increased (p > 0.05) because of the glow-discharge treatment. Contact angle measurements showed an increase (p < 0.05) in surface hydrophilicity.Total void formation in the stone casts decreased. There were no significant differences in the linear dimensional accuracy, detail reproducibility, and hardness, before and after glow-discharge treatment (p > 0.05). Significance. It was concluded that the surface wettability of the impression materials may be increased by plasma deposition, and therefore, the formation of voids was reduced in the stone casts.