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