Recommendations for preparation

Non-suitable: tangential preparation and stair preparation with slope trimmingPreparation recommendations for Cercon restorations follow familiar recommendations for all-ceramic systems. This means that tangential preparation and stair preparation with slope trimming are not suitable for zirconia oxide restorations because with both preparations there originate thin edges threatened by their fracture.
Suitable: preparation for round stair and for stair with rounded internal edge


The following preparation forms are suitable:

  • marked round stair (90°)
  • stair with rounded internal edge

The preparation of the round stair requires cylindrical rounded diamond tools (e.g.:8881.314.016, Gebr. Brasseler, Lemgo). The preparation of the stair with rounded internal edge requires conical diamond tools with the rounded edge (e.g.8951KR.314.014, Gebr. Brasseler, Lemgo).

For reasonable fabrication of all-ceramic preparations in frontal and lateral part there was established a preparation set consisting of 6 diamond tools (Ergo - Präp - Set, TD 1275, Gebr.Basseler, Lemgo).





Circular cross-section depth of 1.0 mmTo finish the preparation there is recommended a use of rotary tools with medium granulation of 30 um. Minimum wall thickness of zirconia framework is 0.4 mm, minimum demand for space for covering by ceramics in cervical area is 0.6 mm. This results in the circular cross-section depth of 1.0 mm which is acceptable.


Lateral teeth restorations
Occlusive loss of substance: 1.5 mm

For the restorations in the lateral part there shall be ensured an occlusive thickness of the covering ceramics of 1.0 mm. With respect to the minimum wall thickness of the framework which shall be 0.4 mm, the loss of the tooth substance on occlusive surfaces is 1.5 mm. The cone angle of the corresponding axial surfaces shall be 3°- 4°. The transitions of axial walls to occlusive surface shall be rounded.

Determination of the fitting direction
Especially with bridge frameworks the determination of the fitting direction shall be considered and there also shall be ensured so that the corresponding stump areas of the bridge posts can show the cone angle of minimum 6°. Very steep sides seem to be vertical lines at scanning process which cannot be exactly shown by the programme.
Simplified occlusive relief

Especially with bridge frameworks the determination of the fitting direction shall be considered and there also shall be ensured so that the corresponding stump areas of the bridge posts can show the cone angle of minimum 6°. Very steep sides seem to be vertical lines at scanning process which cannot be exactly shown by the programme.

Orthorhombic diamond tool (e.g.: 8899.314.027 /palatine grinder/, Gebr. Brasseler, Lemgo) which is conducted vertically to the tooth axis proved satisfactory for the preparation of occlusive parts.




Frontal teeth restorations
Basic warningsPreparation in frontal part shall be oriented according to the mentioned general preparation rules: along with circular cross-section depth with size dimension of 1 mm it is necessary to ensure the cone angle of 6°-8° on preparation borders. The transitions between axial surfaces and palatine surfaces as well as incisional ones shall be rounded (minimum diameter of 0.4 mm).
Thickness of incisional edge

Especially due to the aesthetic reasons the substance occlusive loss shall be 2.0 mm. The minimum thickness of incisional edge in vestibular direction shall be 0.9 mm in order to ensure the precise reproduction of framework internal surfaces by the cutter unit.

Appearance of palatine contour To fabricate the palatine contour of upper incisors and canine teeth there shall be recommended a use of the already mentioned palatine grinder (8899.314.027, Gebr. Brasseler, Lemgo).
HintThe same tool is recommended also for roundness of transitions between the axial walls and incisional edge.  
Ceramic restCercon restorations may be fabricated also with vestibular or ceramic stair, there are ensured sufficient support masses for the covering ceramics Cercon ceram S. The stair preparation in comparison with the laboratory fabrication of the ceramic rest has advantages against the preparation for rounded stair.