Improved water absorption behaviour of experimental hydrophilic vinyl polysiloxane (VPS) impression materials incorporating a crosslinking agent and a novel surfactant

• Published in: Dental materials 2021-06, Vol.37 (6), p.1054-1065
• Main Authors: Ud Din, Shahab, Parker, Sandra, Braden, Michael, Patel, Mangala
• Format: Article
• Language: English
• Subjects: Absorption; Crosslinking; Dental impression materials; Dentistry; Desorption; Diffusion coefficient; Diffusion rate; Dimensional stability; Disinfection; Elastomers; Gravimetry; Hydrophilicity; Hydrophobicity; Immersion; Oleyl alcohol; pH effects; Polysiloxanes; Reagents; Sodium hypochlorite; Solubility; Statistical methods; Submerging; Surfactants; Vinyl polysiloxane; Water absorption; Water uptake
• ISSN: 0109-5641; 1879-0097
• DOI: 10.1016/j.dental.2021.03.019

To study the effects of incorporating a further crosslinking agent and a novel surfactant on the water absorption behaviour of experimental VPS impression materials. Part 1: The water uptake behaviour of Aquasil-Ultra-Monophase (AqM) was studied gravimetrically in three media (DW, 1%NaOCl and Perform ID), at 23 °C and 37 °C, over a period of one and four-months (n = 5) to gain information on long-term immersion. Part 2: Five experimental materials were formulated: Exp-I and II as hydrophobic and Exp-III-V as hydrophilic, containing an additional cross-linking agent (TFDMSOS) and Rhodasurf CET-2 surfactant. Their water uptake and desorption (both at 23 °C) properties (gravemetrically), solubility, pH and diffusion coefficient (DC) data were compared with three commercial, hydrophilic VPS impression materials, over seven days (n = 5). The results were analysed statistically. Part 1: Significant differences in water absorbed by AqM were observed in the three media at 23 °C. Aq M had a significantly higher uptake in 2% Perform ID, than in DW and NaOCl. At 37 °C, over four-months the uptake profiles were more enhanced and differed. Part 2: All Exp and commercial materials significantly increased in weight in both media (DW and 1% NaOCl at 23 °C), with differing uptake profiles and non-reached equilibrium. Exp-VPS absorbed significantly less water than commercial-VPS. Desorption of all VPS from both parts was faster than absorption, followed Fickian diffusion kinetics and reached equilibrium within 1–3 days. Desorption DCs for Exp-VPS were higher than commercial materials (10−10 versus 10−11 m2 s−1). The solubility was higher in 1% NaOCl compared to DW. The pH of DW after immersion of samples significantly increased compared to 1% NaOCl. The incorporation of novel cross-linking agent, TFDMSOS and non-ionic surfactant, Rhodasurf CET-2, (ethoxylated-cetyl-oleyl alcohol) improved the dimensional stability of hydrophilic Exp-VPS in DW and 1% NaOCl. These materials merit further research in producing accurate casts of the patient’s anatomy following disinfection.