Tooth Anatomy

Tooth as very important part of digestive system, consist of some tissues as showed on the left picture. The outer part is enamel which is the hardest part of a tooth, under enamel there is dentine that supports the enamel and absorbs the pressure of eating. Below dentine, there are blood vessels which support nutrition for tooth and also nerves in a part called pulp. Under pulp there is cementum that covers the dentine at the root and it is attached to the bone of the jaw with little elastic fibers. Another important part is gum which is support root to make tooth stay strongly on its place and don't forget bone which is place of gum to attach on.

Human been have two set types of teeth growing. First set is called "milk teeth", it consists of 20 deciduous teeth. The earliest teeth are called teething. Teething can start as early as three months or as late, in some cases, as twelve months. Occasionally a baby may even present with one or more teeth at birth. The typical time frame for new teeth to appear is somewhere between six and nine months.The infant teeth tend to emerge in pairs - first one upper incisor emerges then the other upper incisor emerges before the next set begin to emerge. Milk teeth tend to emerge sooner in females than in males. The exact patterns and initial starting times of teething appear to be hereditary. When and how teeth appear in an infant has no bearing on the healthiness or developmental ability of the child.

The general pattern of emergence is:
1. Lower central incisors (2)
2. Upper central incisors (2)
3. Upper lateral incisors (2),
4. Lower lateral incisors (2)
5. First molars (4)
6. Canines (4)
7. Second molars (4)

Second set called "permanent teeth" consists of 32 teeth. 28 of them appear between the ages of about 6 and 12 years. Permanent teeth do not push deciduous teeth out of their sockets; instead, a group of cells (odontoclasts) forms in front of tip of second tooth and dissolves the base of first tooth. Finally, the first tooth is held in place only by tissues of gum. Deciduous molars are replaced by premolars. The final 4 third molars, or "wisdom teeth" may erupt between 16-21 years.

Permanent teeth are evenly distributed across the mouth's quadrants. Each quadrant of eight teeth has a:

1. Central incisor

• upper jaw: maxillary central incisor
• lower jaw: mandibular central incisor

2. Lateral incisor

• upper jaw: maxillary lateral incisor;
• lower jaw: mandibular lateral incisor

3. Canine

• upper jaw: maxillary canine;
• lower jaw: mandibular canine

4. First premolar

• upper jaw: maxillary first premolar;
• lower jaw: mandibular first premolar

5. Second premolar

• upper jaw: maxillary second premolar;
• lower jaw: mandibular second premolar

6. First molar

• upper jaw: maxillary first molar;
• lower jaw: mandibular first molar

7. Second molar

• upper jaw: maxillary second molar;
• lower jaw: mandibular second molar

8. Third molar (wisdom teeth)

• upper jaw: maxillary third molar;
• lower jaw: mandibular third molar