Dentin surface reproduction with hydrophilic and hydrophobic impression materials

The detail reproduction of ground moist dentin surfaces with hydrophilic and hydrophobic elastomeric impression materials and the transfer of details onto stone casts produced from such impressions were investigated. Practically no difference was found in the detail-reproducing ability of the six impression materials and that of the dies produced therefrom. The surface roughness data were not related to the degree of hydrophilicity determined as the contact angle between water and impression material in spite of the considerable variation in contact angles of the six materials investigated. The critical surface tension of an experimental low-viscosity vinyl polysiloxane material of typical composition was 22.2 and 22.9 mN/m in the uncured and cured state, respectively. The contact angle between water and this compound was 105°. The critical surface tension of wet dentin is reported to be 45.1 mN/m (Glantz, 1969), which means that the experimental impression paste will spread on wet dentin in spite of the pronounced hydrophobicity of the set product.