e. Crown. An artificial crown is a replacement for enamel and other layers of the
natural crown of a tooth. Crowns are commonly made of metal alloys, acrylic resin, or
porcelain. They are classified according to the type of material used in their construction
and the number of tooth surfaces which they cover. For example, a three-quarter crown
gold alloy is a crown made of gold alloy replacing three of the axial surfaces of the natural
tooth crown. A full porcelain crown (or porcelain jacket) is one made of porcelain
replacing all the surfaces of the crown of a tooth. A veneer crown is a full metallic crown
with a porcelain or acrylic resin veneer on the facial surface. Steps in the fabrication of
the various crowns are generally the same as those for the inlay.
f. Fixed Partial Denture. A fixed partial denture, often called a bridge or a fixed
bridge, is a prosthodontic restoration which is fabricated to replace a missing tooth or
teeth and is held in place by crowns or inlays cemented to one or more adjacent natural
g. Pulp Cap. Pulp capping is a treatment procedure in which a material is placed
over an exposed or near-exposed portion of a dental pulp to protect it and facilitate its
recovery from the effects of chemical, mechanical, or bacterial irritation. Calcium
hydroxide is the preferred base material in pulp capping.
h. Cement Base. A cement base is a foundation that is made of either zinc
phosphate cement or zinc oxide and eugenol cement. The cement base is placed in the
deep portions of cavities to protect the pulp from chemical, thermal, or electrical trauma.
i. Rubber Dam. A rubber dam is thin, rubber sheet material used to isolate the
teeth and keep them dry during the performance of certain restorative and endodontic
CLASSES OF CAVITY PREPARATIONS
Cavity preparation is the term used to describe the process of preparing a tooth to
receive a restoration. It includes the removal of decayed material, the necessary cutting
and shaping of remaining tooth structure, and the cleaning of the prepared area. Certain
basic principles of cavity preparation, first advanced by the American dentist, Dr. G. V.
Black in the early part of the twentieth century, still serve as standards. These principles
provide for convenience in placing the restoration, retention of the restoration, sufficient
bulk and strength of restoration and remaining tooth structure, and prevention of further
dental caries. The design of the cavity preparation must take into account the location
and size of the cavity, the stresses to which it will be subjected, and the type of restorative
material to be used. Cavity forms are classified according to the tooth surfaces involved.
a. Class I cavity preparations (pits and fissures) are one-surface preparations
which involve the occlusal surfaces or the occlusal two-thirds of the facial or lingual
surfaces of a posterior tooth or the lingual pits of maxillary anteriors.