Introduction to Dental Anantomy

The mouth is a versatile area of the human anatomy used for respiratory and digestive functions besides other functions such as speech. Teeth form the most important component of the Oral cavity.
In non-mammalian vertebrates the teeth are constantly replaced throughout life, a condition called Polyphyodonty. Most mammals including humans exhibit two sets of teeth. Usually, at birth no teeth are present in the oral cavity . Soon the primary or deciduous teeth erupt in the oral cavity. These primary teeth are later replaced by permanent teeth. Such a condition where two sets of teeth exist is called diphyodonty.

QUADRANTS OF THE MOUTH:
Oral cavity in humans is divided into four quadrants. Each quadrant resembles other three quadrants in morphology. The upper jaw which is called as maxilla is divided further into two quadrants; (i) right maxillary quadrant and (ii) left maxillary quadrant.Similarly, the lower jaw called as mandible is also divided into two similar quadrants (i) Right mandibular quadrant and (ii) Left mandibular quadrant.

HUMAN DENTAL FORMULA:
The human dentition have teeth of 4 distinct morphological types. They are the incisors, canines, premolars and molars.

The number of teeth present in the deciduous and permanent dentition are different and can be represented by a dental formula. The human dental formula for primary and permanent dentition is given below: The formula represent the teeth of a single quadrant.

Dental Formula for Primary dentition

Dental Formula for Permanent Dentition

The teeth of the upper jaw are called maxillary teeth while the teeth of the lower jaw are called mandibular teeth.

Thus in all there are 20 deciduous teeth and 32 permanent teeth.

THE STRUCTURE OF A TOOTH

Each tooth in humans features two primary components: the crown and the root. 

CROWN : That portion of a tooth which projects above the gum line and is visible in the oral cavity.

ROOT : That portion of a tooth which projects into the jaw base and anchors the tooth.

The crown and the root portion of a tooth meet at cemento-enamel junction.

The crown morphology differs from tooth to tooth, Incisors are flat and possess an incisal edge. Canines have one cusp while premolars and molars have two or more cusps.

INCISORS :

They are named so in man because they are used to incise food. They possess thin blade like crowns which are adapted for cutting and shearing food preparatory to grinding. There are two incisors in each quadrant of the jaw. They are termed the central incisors and the lateral incisors.

CANINES :

The canine is present distal to the incisors. It is a large tooth having a single cusp. Morphologically they can be considered transitional between incisor and the premolar. The canines have the longest root in the jaw.

PREMOLARS :

Premolars are found distal to the canine and are unique to the permanent dentition. The replace the deciduous molars. The premolars usually possess two cusps; one buccal and a lingual / palatal, separated from each other by a mesiodistal occlusal fissure. Morphologically the premolars are considered transitional between canines and molars.

MOLARS :

They are teeth that possess the largest occlusal surface having 3 to 5 cusps, The permanent molars do not have deciduous predecessors. They are used for grinding food. The permanent dentition has three molars. They are called the first, second and third molars starting distal of the canine.

The root portion of a tooth can end as a single root or can divide to form two or more roots as seen in molars and certain premolars. The root is held firmly within the jaw base i,e the maxilla and the mandible. The portion of the jaw bone that houses and supports the roots is called the alveolar process.