Teeth
The study of tooth is known as odontalogy.
There are a number of teeth present at the side of oral cavity.
Each of the teeth is embedded in a socket of the bone of jaw in thecodent type of attachment.
Tooth eruption starts by 6-8 month of age.
The central incisors appear first.
Human have diphyodont type of dentition thus they develop 2 sets of teeth, one is temporary or milk teeth and another is permanent teeth.
The temporary teeth in child is also known as milk teeth. There are 20 number of temporary or milk teeth.
The milk dentition starts from 6 months and complete by nearly 2 years of age. The teeth of milk dentition are of 3 types-
1. Incisor
2. Canine
3. Molar
The premolar teeth are absent in temporary teeth.
The temporary or milk teeth are replaced by permanent teeth between 6-12 years.
An adult human has 32 permanent teeth.
The permanent teeth are of 4 types-
1. Incisors- For cutting and biting food
2. Canines- For tearing the food
3. Premolar- For chewing and grinding the food
4. Molar for chewing and grinding the food.
What is the dental formula?
The dental formula is the arrangement of teeth in the half of both jaws in order of incisors, canines, premolars and molars.
It is the equation that represents the number of different types of teeth in each half of upper and lower jaw.
Dental formula of human
The dental formula of human is 2123/2123. The equation for the dental formula of human is
2*(i) 2/2(c)1/1(p)2/2(m)3/3=16/16
The dental formula of human in upper jaw include-
Central incisors — 6 to 7 year
Lateral incisors — 7 to 8 year
Canine or cuspid — 9 to 10 year
First premolar or first bicuspid — 10 to 12 year
Second premolar or second bicuspid — 11 to 12 year
First molar — 6 to 7 year
Second molar — 11 to 13 year
Third molar or wisdom teeth — 17 to 21 year
Similarly, The dental formula of human in lower jaw include-
Central incisors — 7 to 8 year
Lateral incisors — 8 to 9 year
Canine or cuspid — 11 to 12 year
First premolar or first bicuspid — 10 to 11 year
Second premolar or second bicuspid — 10 to 12 year
First molar — 6 to 7 year
Second molar — 12 to 13 year
Third molar or wisdom teeth — 17 to 21 year
Dental formula child
The dental formula child is 212/212. The equation for the dental formula child is
2*(i) 2/2(c)1/1(m)2/2=10/10
The dental formula child of upper jaw include-
Central incisors — erupt in 8 to 12 month & shed in 6 to 7 year
Lateral incisors — erupt in 9 to 13 month & shed in 7 to 8 year
Canine or cuspid — erupt in 16 to 22 month & shed in 10 to 12 year
First molar — erupt in 13 to 19 month & shed in 9 to 11 year
Second molar — erupt in 25 to 33 month & shed in 10 to 12 year
Similarly, The dental formula of human in lower jaw include-
Central incisors — erupt in 6 to 10 month & shed in 6 to 7 year
Lateral incisors — erupt in 10 to 16 month & shed in 7 to 8 year
Canine or cuspid — erupt in 17 to 23 month & shed in 9 to 12 year
First molar — erupt in 14 to 18 month & shed in 9 to 11 year
Second molar — erupt in 23 to 31 month & shed in 10 to 12 year
Structure of a tooth
The structure of tooth consists of three major external parts crown, neck and root.
Crown is the visible part of a tooth. The neck region is middle part which is surrounded by gums and the root part is embedded in the sockets. There are one to 3 roots present in a tooth
The structure of a tooth internally consists of enamel, dentin and pulp cavity.
Enamel
The enamel is the hardest covering of the tooth and is the top most part consisting of calcium phosphate and calcium carbonate. It protects the inner soft part of the tooth.
Dentin
The dentin is the soft inner part next to enamel consisting of calcified connective tissue giving a proper shape and rigidity to the tooth.
Pulp cavity
The pulp cavity of the teeth include a pulp of connective tissue containing blood vessels, lymph vessels and nerves.
There is a narrow cavity running through the roots of the tooth called root canal.
The structure of a tooth is very complicated.
Excellent, found very informative and easy to understand. everyone should read this to understand about human tooth. The part of dental formula is very interesting and explained very uniquely.
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