|
A third molar.Main article: Dental anatomy
Dental anatomy is a field of anatomy dedicated to the study of tooth
structures. The development, appearance, and classification of teeth fall
within its field of study, though dental occlusion, or contact among teeth,
does not. Dental anatomy is also a taxonomical science as it is concerned
with the naming of teeth and their structures. This information serves a
practical purpose for dentists, enabling them to easily identify teeth and
structures during treatment.
The anatomic crown of a tooth is the area covered in enamel above the
cementoenamel junction (CEJ).[3] The majority of the crown is composed of
dentin with the pulp chamber in the center.[4] The crown is within bone
before eruption.[5] After eruption, it is almost always visible. The
anatomic root is found below the cementoenamel junction and is covered
with cementum. As with the crown, dentin composes most of the root, which
normally have pulp canals. A tooth may have multiple roots or just one
root. Canines and most premolars, except for maxillary (upper) first
premolars, usually have one root. Maxillary first premolars and mandibular
molars usually have two roots. Maxillary molars usually have three roots.
Additional roots are referred to as supernumerary roots.
Models of human teeth as they exist within the alveolar bone.Humans
usually have 20 primary teeth (also called deciduous, baby, or milk teeth)
and 32 permanent teeth. Among primary teeth, 10 are found in the (upper)maxilla
and the other 10 in the (lower) mandible. Teeth are classified as incisors,
canines, and molars. In the primary set of teeth, there are two types of
incisors, centrals and laterals, and two types of molars, first and second.
All primary teeth are replaced with permanent counterparts except for
molars, which are replaced by permanent premolars. Among permanent teeth,
16 are found in the maxilla with the other 16 in the mandible. The
maxillary teeth are the maxillary central incisor, maxillary lateral
incisor, maxillary canine, maxillary first premolar, maxillary second
premolar, maxillary first molar, maxillary second molar, and maxillary
third molar. The mandibular teeth are the mandibular central incisor,
mandibular lateral incisor, mandibular canine, mandibular first premolar,
mandibular second premolar, mandibular first molar, mandibular second
molar, and mandibular third molar. Third molars are commonly called "wisdom
teeth" and may never erupt into the mouth or form at all. If any
additional teeth form, for example, fourth and fifth molars, which are
rare, they are referred to as supernumerary teeth.[6]
Most teeth have identifiable features that distinguish them from others.
There are several different notation systems to refer to a specific tooth.
The three most commons systems are the FDI World Dental Federation
notation, the universal numbering system, and Palmer notation method. The
FDI system is used worldwide, and the universal is used widely in the
United States.
|