The purpose of this study was to investigate the relationship between surface hydrophilicity and detail reproducibility of die stone for hydrophilic polyvinyl siloxane impression materials modified with nonionic surfactants.
Hydrophilic polyvinyl siloxane impression materials were prepared with a polydimethylsiloxane composition and nonionic surfactants. The surfactants used were nonylphenoxy poly(ethyleneoxy) ethanol homologs of varying ethyleneoxy chain length. These homologs are designated NP4, NP6, and NP10 according to the mole number of ethyleneoxy group of 4, 6, and 10, respectively. The contact angle, consistency, and detail reproducibility for hydrophilic polyvinyl siloxane impression materials were tested.
The incorporation of nonionic surfactant into polyvinyl silxanes enhanced their hydrophilicity and consequently led to significant reduction in contact angles. Significant differences in contact angle were found among the samples (P<0.05). The contact angle was lowest when NP4 was incorporated even though NP4 is less hydrophilic than NP6 and NP10. This implies that the exposed surfactant concentration on the surface was highest when NP4 was used. The consistency of surfactant-modified silicone impression materials were not affected by the type of surfactants used in this study. However, NP4-modified polyvinyl siloxane impression material showed the highest quality reproduction of the thinnest line, indicating highest wettability with gypsum among the samples.
In conclusion, the surface concentration of surfactant on the silicone impression material was crucial factor in determining wettability. The surface hydrophilicity of surfactant-modified silicone impression materials was of major relevance to the detail reproduction of die stone.