Occlusion building is that part of dentistry that deals with restoring occlusion and articulation if one or more teeth are lost. This recovery from occlusion and articulation can be done with removable, prosthetic devices or with fixed, cast, non-removable devices. The removable provisions are discussed in another chapter '' Prosthetic dentistry '', the permanent provisions are discussed in this chapter.
If a large part of the crown of a dental element has been lost, the remaining part can offer insufficient resistance (resistance) to the acting chewing forces. It may also be that there is still insufficient support (retention) for a plastic restoration.
It can then be decided to provide the element with a crown. In fact, the crown of an element is the part that is visible above the gums. But when in practice the term crown is used, this usually refers to a cast or baked restoration that completely or partially replaces the crown portion of an element. The shape and function of the element can be restored with a crown.
A bridge can be manufactured if one or more elements are lost. The bridge is a non-removable cast restoration that replaces the lost elements and has a foundation of at least two ground, so-called pillar elements. The forces acting on the bridge are supported by these pillar elements and their periodontium (periodically worn). With a removable dental prosthesis, the forces are absorbed by the mucosa (mucosal support).
The group of permanent restorations include – in addition to the crown and the bridge – the inlay, the onlay and the facing.
An inlay is a cast metal and / or porcelain restoration that lies within the tooth crown. We speak of an intracoronary restoration. An example of this is a porcelain MOD. An onlay is a restoration located partly inside and partly outside the tooth crown that covers one or more nodules of the original tooth crown. A restoration located outside the crown is called extracoronary. As with the inlay, metal and / or porcelain is used as the material.
A facing is a porcelain shield cemented on the buccal side of an element. Usually the element is first ground to make room for the porcelain. Facings are applied for aesthetic reasons, to mask discolorations or to adjust the shape of an element.
The fixed cast restorations are made in a laboratory. They are indirect restorations. The patient must make prints to copy the situation in the mouth (see images below).
Crown and bridge work include extensive, time-intensive treatments that are costly. That is why there must be a good preliminary investigation and treatment plan. In the dental examination the dentist looks at the following aspects:
- The patient's oral hygiene.
- The state of the periodontium.
- Occlusion and articulation in the mouth. Occlusion is a static contact between upper and lower elements and articulation is a sliding or dynamic contact. The lower jaw can move sideways (lateral articulation) and forward (protral articulation) from occlusion.
The lateral (lateral) articulation can proceed in two patterns:
- Cuspidate guidance: if the lower jaw moves to the left or right, only the cuspidates on the relevant side make contact. The entire chewing movement is carried by the cuspidates.
- Group guidance: when the lower jaw moves to the left and right, the C, P1, P2, M1 and M2 all make contact on the side to which the lower jaw is moved. The chewing movement is then carried by all elements in the lateral parts. With protral (forward) articulation, in an ideal situation all upper front elements will touch the lower front elements equally. The premolars and molars do not touch each other (see image below).
- The state of the element concerned. There must be sufficient support and firmness for the restoration. If the remaining stump offers insufficient support, it will first have to be assembled.
- The vitality of the element involved. An X-ray is a good tool for assessing the condition of the periodontium and apical area.