[Foundations and methods of rational crown preparation]

The targeted removal of dental hard tissues for the purposes of crown stump preparation may be designated as rational if the technique used ist atraumatic and implies the deliberate use of driving systems within different speed ranges and the utilization of adapted abrasive tools in a phase-synchronous and segment-oriented manner. Goal of the preparation is to realize a copy of the clinical crown that is reduced in size, presents less details and has a defined line of preparation.