Tooth crowns restore the shape, function and appearance of heavily damaged natural teeth. Their preparation requires at least 2 mm of preserved healthy tooth structure above the gum, so that the tooth can function properly for a long time.
Dental crowns are divided into several types, depending on the material they are made of:
- 1. Metal-ceramic crowns – this construction is made of several layers. They consist of metal interior over which the ceramic layers are applied. The colour of the ceramic layer is selected according to the adjacent natural teeth, so that it resembles them as much as possible. These crowns have been used for many years and have proven to be a very good tool for restoring severely damaged teeth, as well as making a bridge for missing teeth. The metal base does not allow light to pass through as with natural teeth. In case of high aesthetic requirements and front teeth, it is best to use non-metal crowns (entirely made of ceramics).
- 2. All-porcelain crowns (the so-called pure ceramics) – these crowns do not have a metal skeleton, but are made entirely of porcelain.
Porcelain is a semi-permeable material for light that is as close as possible in optical properties to the natural tooth structures. The preparation of these crowns includes layering of ceramic mass of different colour and transparency for maximum resemblance to the adjacent natural teeth. They have excellent aesthetic and mechanical qualities.
All-ceramic crowns need less tooth removal than metal-ceramic crowns, which makes them gentler for the teeth. The disadvantage of the pure ceramics is the impossibility of making bridges in the absence of rear teeth.
- 3. Temporary crowns can be made of different materials, depending on the time they are needed for. They have several functions:
- – They protect the filed tooth during the preparation of the final crown in the dental laboratory.
- – They form the soft tissues before taking impression for the permanent crown.
- – They serve as a previsualisation of the permanent crowns for the patient (shape, size, bite and speech).
- – When changing the bite vertically for complete restorations of all teeth, the temporary crowns check the new position and size of the teeth and how they work.
Crown over an implant
In case of tooth loss from complications of some cavity or trauma, the most advanced option to solve this problem is implant placement. The implant is a titanium screw that is placed in the bone. It does not restore the missing tooth, but is the supporting structure for the stump over implant (superstructure) and the crown that restores functionally and aesthetically the missing tooth.
The stages of placing the implant and the crown are:
- – The implant is placed.
- – A period of osteointegration (knitting of the implant with the bone) is waited.
- – The implant is revealed and the abutment over implant (superstructure) is placed.
- – A temporary crown is placed.
- – The soft tissues are shaped with the temporary crown.
- – The final crown is placed.