Comparison of Dimensional Accuracy and Surface Detail Reproduction of Two Hydrophilic Addition Reaction Silicone Impression Materials Under Dry, Moist, and Wet Conditions

Objectives: A severe limitation of polyvinyl siloxane impression materials is hydrophobicity. To eliminate this problem, manufacturers have added surfactants and labeled the new products hydrophilic polyvinyl siloxanes. The purpose of this investigation was to compare the dimensional accuracy and surface detail reproduction of two hydrophilic addition reaction silicone impression materials made under dry, moist, and wet conditions. Methods: 102 Polyvinyl siloxane impressions were made of stainless steel metal dies similar to those described in ANSI/ADA specification No. 19, with vertical and horizontal lines inscribed on the surface. Impressions were made under dry, moist, and wet conditions. Dimensional accuracy was measured by comparing the average length of the middle horizontal line in each impression to the same line in the standard die under a measuring microscope with an accuracy of 0.001 mm. Surface detail reproduction was evaluated in two ways: 1) ANSI/ADA criteria for satisfactory surface detail reproduction and 2) classified by surface characteristics: smooth and shiny, rough and chalky, or pitted or wrinkled. Results: For dimensional accuracy, conditions did not cause significant adverse effects for each material, however significant differences were found between the two materials (p<0.05). Both materials performed satisfactorily in respect to detail reproduction under dry and moist conditions, but not under wet conditions according to ADA specification No. 19 recommendations. Smooth surface reproduction found that both materials performed satisfactorily only under dry conditions, while under moist and wet conditions, both materials performed inconsistently. Conclusions: Changes in dimensional accuracy were within ANSI/ADA guideline recommendations. Satisfactory results were dissimilar between ANSI/ADA detail reproduction standards and those of smooth surface evaluations. Therefore, detail reproduction criteria set in ANSI/ADA specification No. 19 should not be the only evaluation for surface quality of elastomeric impression materials.