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 TV gypsum product (Silky-Rock, Fuji Rock, Suprastone, or Vel-Mix). Using x12 magnification, 2 independent examiners scored the reproducibility of a 20-mu m 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-mu m line. Different impression materials showed different compatibility with different Type TV gypsum products. Only 25% of the Type IV gypsum casts completely reproduced the resultant 20-mu m 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.