Two Year Molars

Amy's teeth, just as with all adults, are her second set of teeth. Every human is born with two sets of teeth that are hidden in the upper and lower jaws. At about six months of age, individuals begin to get their first teeth, called baby or deciduous teeth. The first set of teeth will continue to penetrate through the gums up to about two years of age, until all 20 teeth have emerged. The first set consists of eight incisors, four canines, and eight molars (Figure 5.1a).

The second set of teeth, called permanent teeth, begins to push the baby teeth out at about seven years of age. The permanent teeth continue to come into the mouth up to about age 25, when the wisdom teeth have emerged. A complete set of permanent teeth consists of eight incisors, four canines, eight premolars, and 12 molars, totaling 32 teeth (Figure 5.1b).

All teeth have basically the same structure (Figure 5.2). The visible part of the tooth, the crown, is covered with hard enamel. The enamel cannot be replaced. If it is damaged, the underlying tissues of the tooth may be exposed, resulting in the

Incisors: central (6-8 months)-

Canine(eyetooth): (16-20 months)

Molars: first molar (10-15 months)-second molar: (about 2 years)-

Incisors: central (6-8 months)-

Canine(eyetooth): (16-20 months)

Molars: first molar (10-15 months)-second molar: (about 2 years)-

Teeth Biology
  • Incisors: central (7 years) -
  • lateral: {8 years) -

Canine (eyetooth): (11 years)

  • Premolars (bicuspids): -
  • first premolar (11 years)

second premolar: (12-13 years) Molars: first molar (6-7 years) ]— second molar: (12-13 years)

third molar (wisdom tooth): (17-25 years)

Second Molars Baby

Figure 5.1 Humans are born with two sets of teeth: deciduous (milk) teeth (a) and permanent teeth (b). The deciduous teeth erupt from the gums around six months of age, and generally finish growing at about two years. At about age 7, a child will begin to lose his or her baby teeth, which will gradually be replaced by the permanent teeth.

degeneration and loss of the tooth. The shape of the crown determines whether the tooth is an incisor, canine, or molar.

The neck of the tooth starts at the gum line and extends through the gum. More of this portion of the tooth may be exposed if the gum recedes with age. Below the neck, the root of the tooth is embedded in the jawbone. The root is held in place by a calcified type of connective tissue called cementum

Cavity Below Gum Line
Figure 5.2 Teeth are very hard structures, as they are used for chewing. Teeth are made up of two sections: the crown, which lies above the gum, and the root, which lies below. The crown covers the dentin, which reaches into the root cavity. The root contains blood vessels and nerves.

that attaches the tooth to a periodontal ligament. Depending on the type of tooth, teeth may have from one to three roots.

Dentin, a bone-like substance, extends through the crown, neck, and root of the tooth and makes up the bulk of the tooth. Although enamel cannot be replaced, dentin can, so there is some repair of damage or decay throughout life. The central core of each tooth is filled with a mixture of connective tissue, blood vessels, and nerves called pulp. This pulp extends through the tooth to the base and forms the root canal.

0 0

Post a comment