Individual crowns can be fabricated from metal, in most cases gold, from metal covered with tooth-coloured plastic or ceramic, or completely metal-free from ceramic only. Although dentists and insurance funds consider crowns as a kind of dentures, a crown doesn’t substitute a tooth. It is supposed to restore the tooth anatomically and functionally correctly.
Basically, all crowns result from teamwork between the dentist and the dental technician. That’s why your dentist will make mouldings of the ground tooth and of the opposite jaw as well as some bite records so that the technician gets all the informations required for manufacturing a crown.
Until the crown is done, the patient receives a temporary crown to protect the tooth. Depending on the kind of the crown, in the next sitting or after an additional fitting, it can be tried in and the dentist checks its fit and marginal integrity. Then, the crown can be bonded using a special cement. There are various kinds of crowns: - full cast crowns
Due to their excellent stability, full cast crowns (metal-coloured, mostly gold) are recommended for molars. - crowns with a plastic cover. This is the easiest way to fabricate a tooth-coloured crown. Basically, it is a full cast crown but its visible surface is covered with a tooth-coloured veneer. Because of their relatively soft material, plastic covers are more prone to stainings caused by smoking, tea, coffee or red wine and to abrasion.
Patients should consider that every plastic cover is more likely to fracture due to the shearing forces when chewing or grinding the teeth. Compared to indirect restoration in a laboratory, direct restoration inside the mouth in most cases cannot provide an ideal result. It is not possible to fabricate a full plastic veneer since a gold frame is necessary for static reasons. - porcelain-fused-to-metal crowns.
All porcelain-fused-to-metal crowns are fabricated individually in a laboratory. This is a very elaborate process which includes many steps such as moulding and fusing. This provides hardness and material integrity and protects the crown from stainings and fracture. However, in case of a porcelain veneer, only the visible part of the crown is tooth-coloured. The chewing surface is done from metal. - crowns with full ceramic veneer Here, the tooth is only covered with a thin metal shell which protects it. Over it there is a three-dimensional ceramic shell which provides an excellent naturally looking result. For the reasons of construction, on the tongue side there still may be a thin gold edge.
Modern ceramic materials are not so hard as before which makes the chewing more comfortable. Besides, the wear on opposite teeth is not higher than in case of natural enamel. - fully veneered crowns with ceramic shoulder Have you ever noticed that perfidious blue shimmer on incisors that indicates artificial teeth in spite of a generally good appearance? It is not always possible to avoid this visual defect when manufacturing a convenient construction since both metal and porcelain end at the preparation border.
If you set great store by aesthetics, a ceramic shoulder may provide a solution. However, this service is not covered by compulsory insurances. - All-ceramic restoration? The advantages of all-ceramic restoration are as follows: - better aesthetics since porcelain is most similar to natural enamel due to its brilliance and transparency. - metal-free construction excludes the possibility of metal allergies and galvanic elements in the mouth. - long duration - In contrast to veneered crowns, no dark edges are visible even in case of shrinking gums. - tooth substance is not damaged - Especially on the front teeth it is often possible to apply partial porcelain veneers instead of convenient crowns so that no large preparations on the palatal side are required.