Evaluation of Elastomeric Impression Materials’ Hydrophilicity: An in vitro Study

Abstract

Introduction: Hydrophilicity of dental impression materials is crucial for obtaining an accurate impression and necessary for the production of a well-fitting cast restoration. The most common technique for evaluation of hydrophilicity is a contact angle measurement. The aim of the present in vitro study was to compare the water contact angles of four groups of elastomeric impression materials, before and during setting. Material and methods: Flattened specimens (n=10) of tested impression materials were prepared by the use of a Teflon mold with specific dimensions. A 5μl droplet of deionized water fell on the specimen, and photos were taken using a Nikon D3200 DSLR camera and a 105 mm macro lens (Nikorr, Nikon) in specific time points. Results: A comparison of the contact angle measurements of the impression materials initially, after mixing, revealed statistically significant differences (p<.05).  it was found that PE impression material had significant lower contact angle initially comparing to the CAD.The contact angles measured during setting were significantly lower compared with those measured at initial time points for all the tested groups. Moreover, all tested impression materials presented a stepwise development of hydrophilicity in the setting stage, which was not observed at the initial time point t1. The PE presented lower measured contact angle values both at t1 and t2 examined time points. Conclusions: It was concluded that the PE impression material presented statistically significant lower contact angles initially comparing to CAD. Both impression materials developed a stepwise hydrophilicity.