Reaction of the rat molar pulp to direct capping with the separate components of Hydrex

Teeth treated with Hydrex, a hard-setting calcium hydroxide pulp-capping material, have shown pernicious features on the pulp. Hydrex is presented as two pastes which are mixed before use. Since one of them is based on calcium hydroxide, which promotes secondary dentin formation, it was thought that the resin-based paste is probably responsible for the deleterious effects. The present study performed on rat molars has shown that, whereas most of the pulps of teeth treated with the Hydrex base were healthy, all of those capped with the Hydrex catalyst presented pathologic changes, most of the pulps being necrotic.