Three impression materials, Impregum, Permadyne, and Reprosil, were tested with three restorative materials, Lodestar, Dispersalloy, and Concise. Polished cylindrical samples of each restorative material with and without a collar design were used for impression retention testing. A pullout test using an Instron machine was used to test the samples that were individually submerged in the impression materials until set. Results show similar behavior for Lodestar and Dispersalloy with and without a collar. Permadyne and Impregum were significantly more retentive with resin composite than was Reprosil. Resin composite was significantly more retentive than the metals. Impression materials may bond with restorative materials, significantly increasing resistance to impression removal.