Each molar has four or five cusps, is shorter and more
blunt in shape than other teeth and provides a broad
surface for grinding and chewing solid masses of food.
The teeth of the upper arch are called maxillary
teeth, (fig. 4-12) because their roots are embedded
within the alveolar process of the maxilla. Those of the
lower arch are called mandibular teeth because their
roots are embedded within the alveolar process of the
mandible. Each arch contains 16 teeth. The teeth in an
arch are composed of 6 anteriors (cuspid to cuspid) and
10 posterior (all teeth distal to the cuspids). In a
quadrant, there are 3 anterior and 5 posterior teeth.
Each dental arch is divided into a right and a left
quadrant. The quadrants are formed by an imaginary
line called the midline that passes between the central
incisors in each arch and divides the arch in half
(fig. 4-13). There are four quadrants in the mouth (two
Figure 4-12.Maxillary and mandibular arches showing
relationship of the bones and teeth.
Figure 4-11.Working surfaces of human teeth.
cuspids, also referred to as canines, are at the
angles of the mouth. Each has a single cusp in stead of
an incisal edge and are designed for cutting and
Bicuspids, also referred to as premolars, are
similar to the cuspids. They have two cusps used for
cutting and tearing, and an occlusal surface that is
wider to crush food.
Molars are located in the back of the mouth; their
size gradually gets smaller from the first to third molar.
Figure 4-13.Maxillary and mandibular arches divided into