General dentistry, also referred to as operative dentistry, remains the primary responsibility of the general dentist. This chapter presents background knowledge and describes the skills needed for the clinical dental assistant to gain knowledge of restorative and esthetic procedures such as amalgam restorations, composite resin restorations, intermediate restorations, resin veneers, and tooth-whitening procedures.

Restorative dentistry is indicated when teeth are to be restored to their original form and shape through the use of direct and indirect restorative materials. Specific conditions that determine the need for restorative dentistry include the following:

• Initial or recurring decay (cavity)

• Replacement of a failed restoration

• Abrasion or wearing away of tooth structure

• Erosion of tooth structure

Esthetic dentistry is devoted primarily to improving the appearance of teeth by repairing imperfections with direct and indirect restorative materials, or by using whitening techniques. Specific conditions that result in the need for esthetic treatment include the following:

• Discoloration caused by extrinsic or intrinsic staining

• Anomalies caused by developmental disturbances

• Abnormal spacing between teeth

• Trauma

Cavity Preparation

To restore a tooth to its normal function while still maintaining its esthetic appearance, the dentist must master a technique that involves following specific steps to complete the process of restorative dentistry. When preparing a tooth for a permanent restoration, the dentist has acquired knowledge about the direction of the enamel rods, the thickness of the enamel, the body of the dentin, the size and position of the pulp, and the crown of the tooth as it relates to the gingival tissues.

Terminology

An understanding of the terminology of a cavity preparation will help you to know which dental instruments, dental accessories, and dental materials to have ready at the appropriate times throughout a procedure. The specific terminology refers to the anatomical structures as they relate to the cavity preparation, which is especially helpful for the expanded-function dental assistant (EFDA) in the application of dental materials and intermediate restorations. See Box 48-1 for tooth preparation terms.

BOX 48-1

Terminology Related to Cavity Preparation

Tooth Preparation Walls

Cavity wall: Internal surface of the tooth prepared for the restoration.

Internal wall: Cavity wall/surface that does not extend to the external tooth surface.

External wall: Surface of the tooth preparation that extends to the external tooth surface; named according to the tooth surface involved: distal, mesial, facial, lingual, or gingival.

Axial wall: Internal wall/surface of the prepared tooth that runs parallel to the long axis of the tooth.

Pulpal wall: Internal wall/surface of a prepared tooth that is perpendicular to the long axis of the tooth; also known as the pulpal floor.

Enamel wall: Portion of a prepared external wall that consists of enamel.

Dentinal wall: Portion of a prepared external wall that consists of dentin.

Tooth Preparation Angles

Line angle: Angle formed by the junction of two walls/surfaces in a cavity preparation (similar to the angle formed when two walls of a room meet to form a corner). To identify a line angle, the names of the two involved walls/surfaces are combined. For example, the angle formed by the mesial and lingual walls is called the mesiolingual line angle; the suffix –al of mesial is dropped and the letter o added. The two terms are then combined to form the term mesiolingual. It is important not to confuse the names of these angles with the names used to describe the surfaces involved in the restoration itself.

Point angle: Junction of three walls/surfaces that are coming from a different orientation.

Cavity preparation is the process of removing diseased tooth structure while leaving a limited amount of healthy tooth structure for the tooth to maintain a restoration. The principles of cavity preparation are divided into two stages, each with several steps. The dentist follows these steps in an exact order so that ideal results are achieved.

Permanent Restorations

A permanent restoration can be anything from a small class I restoration to an extensive class II multisurface foundation. With the exception of steps added to the process by using supplementary accessories and dental materials, a restorative procedure will follow a standardized format.

Class I Restorations

The class I cavity, or lesion, is a one-surface lesion involving the pits and fissures of a tooth. Because of this anatomical feature, plaque and debris will accumulate within these areas, making it difficult for a patient to keep the areas clean. Therefore, the pits and fissures are highly susceptible to decay. Class I decay involves the following areas of concern:

• Occlusal pits and fissures of premolars and molars (Fig. 48-5, A)

• Buccal pits and fissures of mandibular molars (Fig. 48-5, B)

• Lingual pits and fissures of maxillary molars (Fig. 48-5, C)

• Lingual pits of maxillary incisors, most frequently near the cingulum (Fig. 48-5, D)

FIG. 48-5 Class I restorations. A, Occlusal pits and fissures of premolar/molar. B, Buccal pits and fissures of mandibular molars. C, Lingual pits and fissures of maxillary molars. D, Lingual pits of maxillary incisors.

Tooth Preparation

The occlusal or lingual class I cavity preparation is a simple preparation for the dentist. The outline of the cavity preparation involves the pit, the groove, or a fissure that is decayed. The dentist will use a bur to open the enamel, taking care not to create any sharp angles or corners within the preparation. This preparation should be smooth throughout the internal structure (Fig. 48-6).

The location of the restoration in the mouth will determine the type of permanent restorative material to be used. Because class I lesions are small restorations and most likely do not interfere with occlusal forces, the dentist will commonly select a composite resin material for the permanent restoration.