Crowns and bridges
The crown is the visible, upper part of the tooth or molar; this part is much smaller than the other, non-visible part – the root. The outside of the crown consists of a very hard material: enamel. The rest of a molar or tooth is composed of cementum. Cementum is less hard than enamel. Inside the cementum, blood vessels and nerves can be found.
In addition to a natural crown, one may also have an artificial crown. This is a hood of ceramic and/or metal which exactly fits a tooth or molar, and is glued into place. An artificial crown will be used when there is insufficient grip for a filling when a tooth is severely decayed. Or there may be cosmetic reasons; this usually involves poorly shaped or discoloured teeth.
First, sufficient dental material must be removed with a drill in order to make room for the porcelain crown and the crown substructure. After this, a dental impression is made. The material used for the impression may be made from various materials, for example, hydrocolloid, polyether, silicon or other polymers. Nowadays, so-called mouth scanners are used, which take over the task of the impression plates. One then has a three-dimensional image of the tooth in question. This print is then usually sent to a dental laboratory.
The manufacture of a crown is precision work carried out by a dental technician. The finished product is returned to the treating dentist, who glues the crown onto the filed down tooth or molar.
Nowadays, dental implants are used to anchor multiple crowns (Implantology).
A dental bridge is a construction used to replace one or more absent natural dental elements, and is attached to neighbouring dental elements. A classic bridge contains a single cast-metal structure (a gold or stainless steel alloy) covered in porcelain. Today, instead of gold, a lot of work is done with zirconium oxide.
Zirconium (IV) oxide is mainly used in ceramics. However, it has also become popular in the field of dentistry, for the manufacture of crowns and bridges. Cubic zirconia is the cubic crystalline form of zirconium (IV) oxide. This material has features that come closer to the characteristics of diamond than any other material. It is therefore implemented as a pseudo-diamond. The beauty of this material is that it is opaque and the right colour. There are no “dark edges” anymore.
The element that replaces the missing teeth is called the pontic. The teeth that hold the bridge are called the abutment teeth. The abutment teeth are filed down by the dentist. A bridge consists of at least two crowns with at least one pontic element. Implants can also be used as abutments. Bridges are categorised according to the material from which they were made or according to their shape.
A Maryland bridge (or adhesion bridge or tack bridge or etching bridge) is a tissue-saving technique used to replace a missing tooth by fixing an artificial tooth to the surrounding teeth. This technique was developed at the University of Maryland, hence the name. A Maryland bridge consists of a metal base with a tooth of fired porcelain on top. It looks like a tooth with two metal wings. These two metal wings are glued on the palatal aspect to the neighbouring teeth at either side. Preparation of the neighbouring teeth is minimal. The palatal aspect of the neighbouring teeth is cut into a number of grooves. The Maryland bridge is stuck onto the teeth to the left and right of the missing tooth using a composite or a modified composite. Fixation is mainly via the adhesive strength of the composite. A Maryland bridge is only possible if there is enough space between the lower and upper teeth. The Maryland Bridge can also occasionally be considered a temporary solution in anticipation of an implant or a classic bridge. This is because the Maryland bridge has a shorter lifespan.
Crowns and bridges are aesthetically beautiful and durable solutions. You might want to consider them yourself!