Effects of the temperature of cooling water during high-speed and ultrahigh-speed tooth preparation.

In vitro measurements of heat production in the pulp chamber during tooth preparation were performed on intact third molars. The experiments were designed to simulate physiologic temperature conditions in the tooth and oral cavity and to standardize parameters of tooth preparation. Two drive systems, the turbine and the high-speed angle, were compared by using two ranges of cooling water temperature. The critical temperature of 41 degrees C to 42 degrees C that is irreversibly harmful to pulpal tissue was not reached with a cooling water temperature of 30 degrees C to 34 degrees C. Because the temperature elevation during turbine preparation was dependent on the diminishing thickness of remaining dentin, in preparing teeth close to the pulp, a high-speed angle was advantageous.