Effect of surface treatments on the wettability of vinyl polysiloxane impression materials

A number of vinyl polysiloxane (VPS) impression materials are claimed to be hydrophilic, but it has been hypothesized that the degree of hydrophilicity may be altered by the exposure to saliva, disinfecting agents, and surfactants.

This study compared the effects of 6 treatment regimes on the hydrophilicity of 3 VPS materials.

Three VPS materials (Dimension Garant L, Hydroflex, Imprint II, referred to as G, H, and I, respectively) were each treated with: (1) nothing (control), (2) saliva, (3) saliva and NaOCl, (4) saliva and 2-propanol-based disinfectant, (5) saliva, NaOCl and surfactant, and 6) saliva, 2-propanol-based disinfectant, and surfactant. Advancing contact angles (thetaA) were measured using a Cahn Dynamic contact angle analyzer and WinDCA software. Using saturated CaSO4 solutions, thetaA was determined for the 3 materials in each of the 6 conditions. For each combination of VPS and treatment, 5 determinations were made using fresh samples and fresh solution each time. Considerable contact angle hysteresis was observed. Two-way ANOVA was performed, followed by post-hoc Boneferroni-Dunn tests.

For all outcome variables, the treatment effects were not the same for all materials (P < .001). However, for all materials, treatments that included surfactants were among the groups with the lowest thetaA values and thus had the best wettability. For example, materials G and I, as made, had high thetaA values (109.7 and 115.2 degrees, respectively), but these values reduced to approximately 90 degrees after surfactant treatment. Material H had a thetaA value of 87.1 degrees. Exposure of material H to saliva and/or a disinfectant raised this value, but a thetaA close to the original value was achieved by the use of a surfactant.

Treatments affected the VPS materials in different ways but, after disinfectant treatment, the wetting of "hydrophilic" VPS materials was improved by surfactant treatment.