[Rational methods of crown preparation].

Today, a rational technique of crown preparation seems to be defined by the following features: 1. Speed-conscious operation 2. Sectionalization into a phase of coarse preparation and a phase of fine preparation 3. Phase-synchronous and segment-oriented coarse preparation in the maximum speed range 4. Fine preparation by means of abrasive tools to achieve a defined preparation limit in the high-speed range 5. Finishing with the aid of properly formed diamond stones or tungsten-carbide finishers in the normal speed range 6. Speed-dependent supply of cooling water according to the principle of double safety (spray and additional cooling).