Abstract: Improved two component polymerizable polyorganosiloxane compositions are described, particularly for use in making dental impressions, having improved tear strength and wettability. Improved tear strength results from inclusion of a quadri-functional polysiloxane having a vinyl content of 0.16 to 0.24 m-mole/g. Working time is maintained by including sufficient amounts of a retarder composition that delays onset of the vinyl polymerization. Wettability is improved by including a surfactant resulting in a surface contact angle with water at three minutes of less than 50.degree.. The surfactant chosen has an HLB of 8-11, such that the wetting contact angle is achieved within less than two minutes and remains wetting throughout the working time of the impression taking, substantially improving the impression making process.

Abstract: A method of preparing an impression of dentition in the oral cavity is provided that overcomes a problem of transfer of inhibitors left by latex gloves that interfere with platinum catalyzed hydrosilation reactions. The method involves applying a surfactant, preferably with peroxide, to the area that is to have its impression taken substantially immediately before applying the impression taking material, rinsing the composition from the area and proceeding with the taking of the dental impression. Preferably the decontaminating composition consists essentially of surfactant, especially polyoxyethylene surfactants, hydrogen peroxide and water.