LESSON 4
DENTAL ANATOMY
Section I. ASPECTS OF THE ANATOMIC DESCRIPTION OF TEETH
4-1.
GENERAL
Teeth are of different shapes and sizes. The primary function of teeth is to chew
(masticate) food. They function in specialized ways in the preparation of food for
digestion. There are two kinds of teeth--anterior and posterior. The anterior teeth are
designed for the purpose of cutting and tearing food. The posterior teeth are designed
for the purpose of grinding or crushing food. Teeth also have a role in speaking, by
aiding in the production of sounds. Another function of teeth concerns appearance
(esthetics). The presence or absence of teeth, their regularity or irregularity of position,
and their color and condition greatly affect the appearance of the individual. The shape,
size, number, and arrangement of teeth in a normal arch are such that they efficiently
perform these major functions. The character and general arrangement of teeth, taken
as a whole, are referred to as the dentition. The individual has two sets of teeth during
his lifetime. The first set is the primary (deciduous or temporary) set of 20 teeth. A later
set is the secondary (permanent) set of 32 teeth.
4-2.
ANATOMIC DIFFERENCES BETWEEN GROUPS OF TEETH
The 32 teeth that are commonly found in the adult dentition have differences and
similarities in form and function. For comparison, the teeth are often grouped as
maxillary and mandibular teeth or as anterior and posterior teeth.
a. Maxillary and Mandibular Teeth. The maxilla and the mandible contain the
same number and types of teeth. There are certain distinct differences between the
teeth of the two jaws. One of the differences is in the mesiodistal width between the
maxillary and mandibular anterior teeth. The normal relationship between the maxillary
and mandibular teeth results in a horizontal and vertical overlap. The horizontal overlap
is called overjet. The vertical overlap is called overbite. This results in a wider arch for
the maxillary teeth to fill. It affects the anterior teeth because of the greater curvature of
the anterior part of the dental arch. (There is little or no lateral curvature in the posterior
part.) Other differences include the number of roots of molars (maxillary molars have
three and mandibular molars have two), the configuration and the outline form of
occlusal surfaces, and the nature of the curvature of vertical crown surfaces.
MD0501
4-2