In this article:
How many teeth do humans have? / Wisdom teeth? / Types of teeth? | The parts of the tooth?
Do you know how many teeth do humans have? Firstly, teeth have a vital role to our health because they are helping us to bite and crush or break down food so that our digestive system can get nutrients out of it.
The number of human teeth depend an age, to understand more, you need to know that there is two type of dentition:
- Primary or temporary teeth: the first teeth that appear for a baby, looks a little bit smaller in size, whiter and less mineralized (also called deciduous or milky teeth), their main function is to maintain space for permanent teeth.
- Secondary or permanent teeth: replace primary dentition in a certain age.
How many teeth do humans have?
We can divide it into three periods:
1- From 6 months to 2 years: Pure primary dentition.
Number of teeth: 20
This period is characterized with presence of only primary teeth: 2 incisors, 1 canine and 2 molars in each quad.
2- From 6 years to 12 years: Mixed dentition.
Number of teeth: 28
The presence of both primary and permanent teeth in this period.
3- From 12 years to 25 years: Pure permanent dentition.
Number of teeth:32
We can find only permanent teeth: 2 incisors, 1 canine, 2 premolars and 3 molars in each quad.
It’s the third permanent molar, they appear in the period of permanent dentition between 17 to 25 years.
Pathological: impacted: mean that there is a cause which is preventing from completely erupting into the normal position, may be due to lack of space, obstruction by another tooth, or an abnormal eruption path.
Types of teeth:
We can find in oral cavity 4 different types of teeth:
1- Incisors – there is frontal and lateral incisors in each quad, in total: eight situated in the front of the month.
Primary incisors are usually the first teeth to erupt for a baby at around 6 months, and between 6 and 8 for permanent incisors for an adult.
2- Canines – sharpest teeth and are used for ripping food. You have 4 canines in your oral cavity: 1 canine in each quad.
Primary canines appear generally between 16 and 20 months for a child, and permanent canines starting eruption in 9 years old till 12 years old. (Lower canines: 9 and upper canines: 11-12)
3- Premolars – for chewing and grinding food. An adult has 8 premolars, two in each quad.
There is no primary canines. The first premolars appear around 10 years old, and second premolars arrive within a year later.
They take place of first and second molars.
4- Molars – also used for chewing and grinding food. An adult has 12 molars, three molars in each quad.
Primary molars appear between 12 and 28 months, they get replaced by first and second premolars, permanent molars arrive between 6 and 25 years old. ( First molars: 6-7 and second molar: 11-13 and third molar (wisdom teeth): 17-25 years old)
The parts of the tooth:
The tooth is divided into two main part:
- Crown: the white part of the tooth which is visible.
- Root: unseen part of the tooth.
Root goes below the gum line and deep into the bone to get the attachment of the tooth.
The teeth contain several types of tissue, each one has a role:
-Enamel: it is the hardest think in all your body, the visible part and cover the tooth crown.
Protects the tissue within your teeth and made from calcium, phosphorous and hydroxyapatite.
-Dentin: the second layer of the teeth.
It is located under the enamel and similar to the bone. However, it is not quite hard as the enamel.
-Cement: found in the root, covers it and help for the attachment of the tooth into the bone with the periodontal ligament, he has usually light-yellow color and covered by the gum and bone.
-Pulp: found in the middle of the tooth and contains blood vessels and tissue that come with nutrients and signals to the tooth.