The tooth preparation with a circular bevel (step-stair bevel), a precise preparation line and precise marginal sealing are basic prerequisites for creating the finest aesthetic ceramic crowns and bridges and healthy and beautiful gums in areas surrounding the crown or the bridge.

Tooth preparation for the ceramic crown with a circular/step-stair bevel and a precise preparation line is done in such a way that in the tooth cervix area, at the level of the gums, we circularly prepare a sharp boundary with a gentle step-stair bevel to which we will place the crown precisely. This way only, we create a precise connection between the tooth and the edge of the ceramic crown, which makes an ideal extension to the tooth root. We call this marginal sealing.

In the case of metal ceramic crowns, the precision of marginal sealing is 20 microns, while in the case of zircon ceramics it is merely 5 microns.
The precision of zircon ceramics is the biggest advantage in comparison to metal ceramics. For this reason, zircon ceramics are most often recommended as the material of choice for dental crowns and bridges.
In this micron-sized space between the ceramic crown and the rest of the tooth, an adhesive dental cement is placed, that attaches the crown to the tooth crown and forms a seal, without any fissures, in such a way that the ceramic crown and the rest of the tooth become "one body".

All this leaves no possibility for food retention in the seal, hence accumulating bacteria that can cause gum inflammation and the emergence of caries below the crowns.