Type IV gypsum compatibility with five addition-reaction silicone impression materials

STATEMENT OF PROBLEM: The compatibility of current addition-reaction silicone impression materials and Type IV gypsum products is not completely understood. PURPOSE: The purpose of this study was to compare surface detail reproduction between various combinations of contemporary addition-reaction silicone impression materials and Type IV gypsum products. MATERIAL AND METHODS: Under standardized conditions, 300 impressions were made of a ruled stainless steel die (ADA specification 19), using 5 addition-reaction silicones (Examix-NDS, Doric-ES Flo-Light, Panasil Contact Plus, Extrude Wash, and President Plus Jet). Fifteen impressions of each material were poured with each Type IV gypsum product (Silky-Rock, Fuji Rock, Suprastone, or Vel-Mix). Using x12 magnification, 2 independent examiners scored the reproducibility of a 20-microm line in both the impression and the resultant casts. Statistical analysis was performed using 2-way analysis of variance and post hoc Bonferroni testing (alpha = .05). RESULTS: All impression materials tested fully reproduced the 20-microm line. Different impression materials showed different compatibility with different Type IV gypsum products. Only 25% of the Type IV gypsum casts completely reproduced the resultant 20-microm line with fine margins, and 88% of the completely reproduced casts were made from Suprastone. CONCLUSION: Not all combinations of impression material and Type IV gypsum products used exhibited similar compatibility.