A dental restoration or dental filling is a dental restorative material used to restore the function, integrity and morphology of missing tooth structure. The structural loss typically results from caries or external trauma. It is also lost intentionally during tooth preparation to improve the aesthetics or the physical integrity of the intended restorative material. Dental restoration also refers to the replacement of missing tooth structure that is supported by dental implants. Dental restorations can be divided into two broad types: direct restorations and indirect restorations. All dental restorations can be further classified by their location and size. A root canal filling is a restorative technique used to fill the space where the dental pulp normally resides.
Restoring a tooth to good form and function requires two steps, (1) preparing the tooth for placement of restorative material or materials, and (2) placement of restorative material or materials.
The process of preparation usually involves cutting the tooth with special dental burrs, to make space for the planned restorative materials, and to remove any dental decay or portions of the tooth that are structurally unsound. If permanent restoration can not be carried out immediately after tooth preparation, temporary restoration may be performed.
The prepared tooth, ready for placement of restorative materials, is generally called a tooth preparation. Materials used may be gold, amalgam, dental composites, glass ionomer cement, porcelain or any number of other materials.
Preparations may be intracoronal or extracoronal.
- Intracoronal preparations are those preparations which serve to hold restorative material within the confines of the structure of the crown of a tooth. Examples include all classes of cavity preparations for composite or amalgam, as well as those for gold and porcelain inlays. Intracoronal preparations are also made as female recipients to receive the male components of Removable partial dentures.
- Extracoronal preparations are those preparations which serve as a core or base upon which or around which restorative material will be placed to bring the tooth back into a functional or aesthetic structure. Examples include crowns and onlays, as well as veneers.
In preparing a tooth for a restoration, a number of considerations will come into play to determine the type and extent of the preparation. The most important factor to consider is decay. For the most part, the extent of the decay will define the extent of the preparation, and in turn, the subsequent method and appropriate materials for restoration.
Another consideration is unsupported tooth structure. In the photo at right, unsupported enamel can be seen where the underlying dentin was removed because of infiltrative decay. When preparing the tooth to receive a restoration, unsupported enamel is removed to allow for a more predictable restoration. While enamel is the hardest substance in the human body, it is particularly brittle, and unsupported enamel fractures easily.