The accuracy of dental elastomeric impression materials greatly depends on their ability to recover elastically after a deformation the greater the recovery, the better the precision. Polyvinylsiloxanes have the ability to absorb over three times more energy up to the point of permanent deformation than other elastomers. Tear propagation energy have been employed as common In vitro method to evaluate tear strength of elastic dental materials. Ideally, impression material should absorb high energy prior to permanent deformation and tears rather than deforms at critical areas. From the clinical perspective, materials with high tear energy or tear strength are not necessarily considered to be superior to the materials with low tear energy or tear strength. The tear of elastomeric materials is commonly initiated and propagated at high stress concentration sites as defects, or deformations within the material. VPES were introduced to represents the blend of hydrophilicity of polyether and excellent elastic recovery as well as the dimensional stability of Polyvinylsiloxanes impression materials. As there is no single impression material meets all of the ideal requirements, significant improvements have been made all over the years, including the introduction of vinyl polyether silicone (VPES) hybrids. On the other hand, PVS has great stability, high tear strength, and excellent recovery, but with a hydrophobic nature. Polyethers have excellent flow and hydrophilic properties, but they are rigid, with slow recovery and low tear strength. Polyvinylsiloxanes (PVS) and polyethers (PE) are the most commonly used rubber base materials for secondary impressions all over the world. The three materials were statistically insignificant from each other, and all met the ISO4823 requirement of having greater than 96.5% recovery. Elastic recovery was evaluated one minute after the setting time recommended by the manufacturer. Tear strength was measured one hour after setting time of each material according to the manufacturer and the three materials showed statistically comparable tear strength in N/mm. ResultsĪ polyether (PE), polyvinyl siloxanse (PVS) and vinyl polyether silicone (VPES) hybrid elastomers were used in the present study. Thus, this study aimed to assess the impact of hybridization between polyether with addition silicone on tear strength and elastic recovery of the new material and compare such effect with regard to parent materials. The aim of the hybridization was to obtain a new material combining the good merits of both and eliminate their shortcomings. Since there is no material in the market met all the ideal requirements of an impression material, thus in an attempt to find one, hybridization between the two most commonly used impression materials were done.
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