Surfaces Of Teeth

For convenience of description and as an aid in denoting the location of areas of decay and restorations, the crown part of a tooth is divided into a number of surfaces. Some of these surfaces are characterized by certain anatomic features such as pits, grooves, and ridges. Every dental specialist should be familiar with these terms. These surfaces are named to indicate the direction each surface faces. See figure 4-5.

a. Lingual. The lingual surface is that surface of the tooth that faces toward the tongue.

b. Facial. The facial surface of a posterior (back) tooth faces toward the cheek.

In some textbooks, it is referred to as the buccal surface because it lies next to the buccinator (cheek muscle). The facial surface of an anterior (front) tooth faces toward the lips. In some textbooks, it is referred to as the labial surface because it lies next to the labia (lips). In this subcourse, the term facial surface will be used.

c. Occlusal. The occlusal surface is the broad chewing surface found on posterior teeth (bicuspids and molars). The occlusal surface faces toward and contacts the teeth of the opposite jaw.

INCISAL EDGE OCCLUSAL SURFACE

MESIAL SURFACE (TOWARD THE MIDLINE)

DISTAL SURFACE (AWAY FROM MIDLINE)

Figure 4-5. Occlusal view of maxillary tooth surfaces.

d. Incisal. The incisal surface is the narrow cutting edge found on anterior teeth (incisors and cuspids). Incisors have one incisal edge. Cuspids have two incisal edges, the distal slope and the mesial slope, that meet at the tip of the cusp. The incisal surface (incisal edge) of an anterior tooth faces toward the teeth of the opposite jaw.

e. Proximal. The proximal surface lies next to another tooth. The tooth surfaces that face each other are called proximal surfaces. The proximal surface includes the entire length of the tooth from the crown to the root tip. Most mesial and distal surfaces are proximal surfaces.

f. Mesial. The mesial surface (toward the midline) contacts the tooth immediately anterior to it (mesial to it) in the dental arch. Following the curvature of the dental arch, it is the surface of a tooth that is closest to or facing the midline (or median line) of the arch. With central incisors, it is that surface which normally contacts the central incisor of the opposite side of the arch.

g. Distal. The distal surface (away from the midline) contacts the tooth immediately posterior to it (distal to it) in the arch. Following the curvature of the dental arch, it is the tooth surface that faces away from the midline (median line). With deciduous second molars and permanent third molars, it is that surface which faces posteriorly in the arch.

h. Axial. The axial surface is any surface of a tooth that is parallel to the long axis of the tooth (see figure 4-6). The long axis is an imaginary straight line passing through the crown and root of the tooth. The facial, lingual, mesial, and distal are all axial surfaces.

Lingual Facial

INCISAL EDGE OCCLUSAL SURFACE

MESIAL SURFACE (TOWARD THE MIDLINE)

DISTAL SURFACE (AWAY FROM MIDLINE)

Figure 4-5. Occlusal view of maxillary tooth surfaces.

Figure 4-6. Axial surface of a tooth.
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