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.