Teeth are important part of human body that are used for chewing, biting and grinding the food we eat. Teeth are attached to the jawbone by a root that goes down into the gums and protrude to outer surface of the gums. The outer surface of teeth is harder so they can be used for eating food.
Human Tooth Composition
What Are Teeth Made Of?
Human teeth are made of multiple tissues of varying thickness and density. Dentin, enamel, cementum and dental pulp are the four major tissues which make up the tooth.
A human tooth is made up of four parts (Look at the following picture of tooth):
- The root extends through the gum and into the bone of the jaw. The roots of teeth are embedded in the maxilla (upper jaw) or the mandible (lower jaw).
- Cementum: The root of the tooth is covered by Cementum which is a bone like substance. The cementum serves as a medium by which the periodontal ligaments can attach to the tooth for stability.
- Inner core: The inner core of the teeth is called the dental pulp and is made up of a soft core containing nerves, arteries and veins.
- An outer harder surface (Crown): The hard material (dentin) of the tooth is composed of calcium, phosphorus and other mineral salts. The outermost layer is an enamel coating covering the tooth. The enamel is the hardest part of the teeth that can be lost with eating excessive acidic food and drinks. Excessive use of hydrogen peroxide to clean the teeth can also destroy the enamel. The normal color of enamel varies from light yellow to grayish white. Enamel varies in thickness over the surface of the tooth and is thinnest at its border and thickest at the cusp, up to 2.5mm.
Number of Roots in a Tooth
Do you know how many roots and root canals are there in a tooth?
- Upper front teeth (incisors) have 1 root and 1 root canal.
- Upper molars have 3 roots and 3 or 4 root canals.
- Lower molars usually have 2 roots and 3 root canals.
Types of Teeth & Teeth Classification
Teeth are classified as
Incisor teeth for cutting off or biting into food such as apples, carrots, radish, etc. The front middle teeth in both the upper and lower jaws are called incisors.
There are a total of four incisor teeth in each jaw, two on either sides of the median line. The first incisor on each side of the median line is called the central incisor and the one next to it is called the lateral incisor tooth.
Cuspids (also called canines) have long sharp points and are used for tearing food. These canines are used to tear into meat and other food that need to be torn before they can be chewed. The canines are found after the four incisors in both the jaws, one on each side of the incisor group.
Premolars and Molars
Premolars and Molars with large relatively flat surfaces used for grinding foods after they are already in bite size pieces inside the mouth. Premolars are found after the canines which are present before the molars and initiate the chewing process. After the premolars there are molars that help to grind the food. The third molar tooth is also called the "wisdom tooth" and erupts much later or may never erupt or form at all.
How Many Teeth Do You Have?
Humans usually have 20 primary teeth (baby teeth) and 32 permanent (adult) teeth. The permanent teeth are 16 in the maxilla (upper jaw) and 16 in the mandible (lower jaw). Each jaw has 6 molars, 4 premolars, 2 cannies and 4 incisors. In all human has following 32 permanent teeth. Toothache reasons and relief
Information on Permanent Teeth Chart
4 central incisors, 4 lateral incisors, 4 cuspids (also called canine), 4 first bicuspids (also called first premolars), 4 second bicuspids (also called second premolars), 4 first molars (also called 6-year molars), 4 second molars (also called 12-year molars), 4 third molars (also called wisdom teeth)
The dental formula for human is (18.104.22.168)/(22.214.171.124). This formula (126.96.36.199) for upper teeth or lower teeth indicates 2 incisors, 1 canine, 2 premolars and 3 molars on one side of the upper mouth; and similar for other side of the mouth.
The first permanent tooth usually appears at around 6 years of age and up to the age of 13 years, 28 of the 32 permanent teeth will appear. The 4 last adult teeth will appear between the ages of 17 and 25 years. This is the reason they are named wisdom teeth. Some people may not develop wisdom teeth even after attaining the normal age of maturity.