When reducing a tooth for a crown, high-speed rotary milling (air-rotor) operations are used. A very high frictional heat is generated when the milling cutter contacts the tooth surface. If sufficient cold water is not sprayed from the milling cutter and the cap during this process, the released thermal energy passes through the enamel and dentin tubules of the tooth and reaches the pulp tissue in the vital center of the tooth. Even a mere 5.5-degree increase in pulp temperature can lead to irreversible damage (thermal shock) to the vascular and nerve network there. In cases of insufficient water cooling, the tooth loses its vitality from within weeks or months after the procedure (pulp necrosis) and abscesses form at the root tip. Therefore, effective water cooling is the most vital clinical requirement for maintaining the vitality of abutment teeth.
