Tear energy of impression materials.

Tear energies are determined for different types of impression materials. Reversible hydrocolloids show the lowest tear energy values, followed by alginate materials. Condensation silicone-, addition silicone-, polyether- and polysulphide impression materials give higher tear energy values. One particular polysulphide material gave the highest value. Tear energy tends to increase as follows: agar-agar, alginate, condensation silicones, polyethers, addition silicones and polysulphides. The highest tear energy values for alginate correspond with the lowest values for condensation silicones. There is considerable overlap of tear energy values within the range of elastomeric impression materials.