Crowns
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A clinical dental crown is the name given to the part of the natural tooth which protrudes from the gum. If some parts are destroyed by caries or a trauma, they can be replaced by fillings or by crowns. The following crowns are distinguished according to the applied materials:
Full crowns consist solely of metal. Silver coloured crowns can consist of a palladium alloy or titanium (non-precious metals). Gold coloured crowns consist of alloys with a greater or lesser proportion of gold.
Faced crowns consist of a thin metal structure, which is individually faced with plastic or ceramics in tooth colour.
Jacket crowns are tooth coloured and do not have a metal structure, that is, they are manufactured solely from polymers or ceramics.
Partial crowns get their name from the fact that they only replace a part of the tooth. Depending on their size they are also called half or three-quarter crowns. They can consist of metal, ceramics or plastic. The transition from inlay/onlay to partial crown is smooth.
Crowns are further distinguished according to construction specific characteristics (e.g., pin crowns, telescope crowns).
Indications for crowns
Crowns are applied to restructure the tooth if caries or trauma has caused a larger loss of the tooth's hard substance or because of severe discolouration. Discolouration causes may be: intake of antibiotics (tetracycline) during the tooth formation phase; intake of too much fluoride (fluorose); dead or removed pulpa after trauma or root canal treatment.
Enamel hypoplasia and form deviations may also justify crown therapy. In enamel hypoplasia, enamel formation is dysfunctional. The tooth's surface is covered with a large number of pits, in which, with time, food pigments are stored, which lead to discolouration. In the case of discolorations and hypoplasias, an alternative to the crown would be the option of bleaching and veneering of these teeth (ceramic veneers).
Form deviations are created during tooth formation either through general illness (e.g., rickets/syphilis) or are congenital (hereditary).
Further, rare indications include:
- Gap closure in the case of diastema by crowning the gapped anterior teeth;
- Specific dental positions;
- Apart from restructuring individual teeth, crowns serve as bridge anchors or attachment elements in malocclusion therapy.
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