TEETH
The teeth are embedded in the alveoli or sackets of
the alveolar ridges of the mandible and the maxilla.
The babies are born with two sets , or dentitions, the
temporary or deciduous teeth and the permanent teeth .
After birth the teeth of both dentitions are present ,
in immature form ,in the mandible and maxilla.
There are 20 temporary teeth, 10 in each jaw.
They begin to erupt when the child is about 6 months
old, and should all be the present by 24 months.
The permanent teeth begin to replace the deciduous
teeth in the 6th year of the age and this dentition,consisting of 32
teeth, is usually complete by the 24th year.
FUNCTIONS OF THE TOOTH
1.
The incisor and canine teeth are the cutting
teeth and are used for biting off pieces of food.
2.
The premolar and molar teeth,with broad ,flat
surfaces, are used for grinding or chewing food.
STRUCTURE OF THE
TOOTH
The shapes of the different teeth vary,the structure is the same and consists
of
1.the crown -
the part that protrudes from the gum.
2.the root – the part embedded in the bone,
3.the neck – the slightly narrowed region where the
crown merges with the root.
The centre of
the tooth is the pulp cavity containing blood vessels ,lymph vessels,and
nerves, and surrounding this is hard ivory-like substance called DENTINE.
Outside the dentine of the crown is a thin layer of
very hard substance, name it has ENAMEL.
The root of the tooth,on the other hand, is covered
with a substance resembling bone, called it has CEMENT ,which secures the tooth
in its socket.
Blood vessels and nerves pass to
the tooth through a small foramen at the apex of each root.
BLOOD
SUPPLY
ARTERIAL BLOOD SUPPLY – Branches of the maxillary arteries.
VENOUS DRIANAGE- Internal
jugular veins.
NERVE
SUPPLY
The nerve supply to the upper
teeth is by branches of the MAXILLARY Nerves and to the lower teeth by branches
of the MANDIBULAR Nerves.
These are both branches of the
TRIGEMINAL NERVES(5th cranial nerves)
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