The effect of various core build-up materials on the polymerization of elastomeric impression materials

ObjectivesThe purpose of this study was to detect whether core build-up materials could be isolated as an inhibitory factor in the polymerization of commonly used types of elastomeric regular set impression materials, and to evaluate several decontamination methods to eliminate the inhibitory effect of core build-up materials.Materials and MethodsThe polymerization of six brands of elastomeric impression materials (Virtual, Aquasil, Genie, Correct Plus, Express and Impregum) was evaluated in vitro after direct contact with various core build-up materials (composite resin, flowable composites and resin-modified glass ionomers). The setting of impression materials was visually scored as either inhibited or non-inhibited independently by three different general practitioners. Different methods to prevent inhibition were also tested. The materials were dispensed according to the manufacturers’ instructions on exposed dentin of the premolar teeth mounted in dental stone. A Chi-square analysis was used to evaluate the results (p < 0.05).ResultsSetting inhibition was found with five brands of Polyvinyl siloxane impression materials when they directly contact four types of core build-up materials. None of the materials used caused inhibition to the polyether impression material. No decontamination method proved adequate in preventing impression material inhibition except grinding 1 mm from the multicore restoration surface. Examiners were in complete agreement (kappa +1).ConclusionsBased on the results of our study and for optimal results, when using Multicore composite as a core build-up material, at least 1 mm from the restoration surface should be grinded before the PVS final impressions are taken. Flowable composites should not be used as a core build-up material with PVS impression materials, so polyether is the material of choice.