Trephination in Two Stages
 
Access cavities for endodontic treatment can be prepared in a reasonable time without additional clinical problems if appropriate tools are selected. A two-stage procedure is recommended for the preparation of the access cavity. To begin with, the veneer ceramic should be abraded with a diamond instrument without perforating the framework.<br>In a second step, the framework ceramic material should be perforated with a diamond-coated instrument in the required size. A distance of 0.5mm from the veneer ceramics should be maintained. Chipping of the veneer material can thus be prevented while the framework ceramic is being cut.

Tip

The structural durability of Cercon crowns is preserved even after endodontic treatment, therefore the restoration can stay in place. It is easiest to close the access cavity with a composite filling. Incidentally, Cercon restorations show a radiopacity that is comparable to metal-ceramic restorations.
Cylindrical diamond instruments with a rounded tip and a diamond grit size of 125-130um (e.g. 6836.314.014 or 5836.314.016, Gebr. Brasseler, Lemgo) in combination with an angled handpiece (4:1 speed transformation at maximum water-cooling) are especially suitable for the preparation of an access cavity and crown removal