What are full ceramic crowns ?
A full ceramic crown is a dental prosthetic made out entirely of porcelain, ceramic crowns were first developed by LANG in 1886. However, their failure rate was very high. The frequent fracture of the crowns was the cause of their temporary abandonment. Improvements in ceramics, refractory linings and bonding techniques have led to the development of bonded all ceramic crowns. A bonded ceramic crown is one of the best treatments for aesthetic restorations.
The advantages of full ceramic dental crowns
Aesthetic: the absence of a metallic cap allows excellent light transmission and therefore a more natural appearance.
No corrosion: Full ceramic crowns do not include metal parts.
Tissue behavior: the perfect adaptation of the ceramic-tooth joint associated with the absence of visible metal edging leads to excellent tissue-crown adaptation.
Biological: eliminates the problems of allergy to metals and dental alloys.
The disadvantages of full ceramic crown
-The making of a dental crown is a complicated process that can take more than one session.
-It needs an experienced laboratory.
-Limited indications: single crown, small bridge.
-Less aesthetic than E-max crowns
Full ceramic crown indications
-Ceramic crowns are essencially indicated front teeth for aesthetic reasons:
-upper and lower front discoloured teeth.
-Severe teeth decay.
-On unsightly teeth (dysplasia or dystrophies).
-Teeth with aesthetic composite reconstructions.
-Allergies to metals and dental alloys.
Full ceramic crown contra-indications
-Crown of the tooth is too short.
-In the presence of malfunction or parafunctions.
The making steps of a full ceramic dental crown
Dental crown preparation
The general shape of the preparation should be similar to that of the natural tooth, this is essential to have a better force mechanical distribution. The principle of dental crown preparation is to reduce the natural surface using burs in order to have the following results:
- Low clearance (6° relative to the major axis of the tooth) allowing a regular and sufficient thickness of the ceramic (aesthetic and mechanical reasons).
- No proximal cantilever zones and free edge.
- The cervical limit is a shoulder with a rounded internal angle with a depth of:
- to 1.2 mm on the buccal surface.
- 1.2 mm on the palatal surface.
- 1 mm on the proximal surfaces.
- The free edge is reduced by 2 mm for a better aesthetic result with an inclination of 15 ° towards the palatal surface.
- Eliminate any sharp angle.
The imprint is a recording of the morphology elements of the dental arch by a material capable of molding its volume and surface. In prosthesis, impression materials allow to save and reproduce dental structures and tissue, and therefore allow the transfer of clinical data in the laboratory.
While waiting for the making of the final ceramic crown, a temporary crown is put for aesthetic and functional reasons, the temporary crown is usually made out of resin or composite.