Human teeth and its structure

  • Human teeth are thecodont, diphyodont and heterodont.
  • They are borne by the premaxillae of upper jaw and mandibles of lower jaw.
  • They are found embedded in jaw sockets which we call thecodont.
  • Human have two sets of teeth.
  • The milk teeth also known as deciduous dentitions appear first and are progressively replaced by the permanent teeth which cannot be replaced.
  • This is known as diphyodont.
  • At birth, the teeth of both dentitions are present in immature form in the mandible and maxillae.
  • The temporary teeth are 20 in number, 10 in each jaw.
  • They begin to erupt when the child is about 6 months old, and should all be present by the end of 24 months.
  • The permanent teeth begin to replace the deciduous teeth in the 6th year of age and this condition is completed by the 24th year with 32 teeth.
  • Teeth are of different shapes and sizes and possess uneven biting surfaces.
  • Human possesses up-to 32 permanent teeth, consisting of 8 incisors (i), 4 canines (c), 8 premolars (pm) and up-to 12 molars (m).
  • The arrangement of teeth is expressed in the form of a dental formula which is given as:

Image result for dental formula

  • Third molar appears only when one will cross the age of 20 years. So, they are called wisdom teeth.
  • They may not appear in the case of certain person sometimes.
  • The number, size and shape of teeth are directly affected by diet.
  • On the basis of structure and function of each type of tooth, four different types of teeth (heterodont) are as follows:

Image result for types of teeth  Image result for types of teeth

a) Incisors

  • They are situated at the frontal region of buccal cavity.
  • They have got flat and sharp edges. They are used for cutting and biting food.

b) Canines

  • They are pointed dagger-shaped teeth.
  • They are poorly developed in humans, but highly developed in carnivores used for piercing and tearing flesh.

c) Premolars

  • They are broad and strong having one or two roots and two cusps (projections on the surface of tooth).
  • They are used for crushing and grinding food, although in human they may also be used to tear food.

d) Molars

  • They have more than one root; upper molars have three roots, lower molars have two.
  • Each has four to five cusps.
  • They are used to crush and grind food.


Structure of a tooth

  • A typical tooth consists of three parts. They are:

Image result for structure of tooth        Image result for structure of tooth

i) Crown

  • It is the exposed part of tooth.
  • It is covered with the hardest substances called enamel.
  • It is relatively resistant to decay.
  • Internally, it has the hard substance called dentine.
  • Inside the dentine is a cavity called pulp cavity which is lined by a layer of odontoblast cells.
  • The pulp cavity contains connective tissues, blood vessels and nerve endings.
  • Chemically the dentine is bone-like and contains many fine canaliculi.

ii) Neck

  • It is a short part embedded in gums.

iii) Root

  • This part is embedded in bony jaw that holds the tooth.
  • Blood vessels and nerves pass to the tooth through a small foramen present at the apex of each root.
  • The number of root vary in different teeth.




Human teeth and its structure