Sunday, February 11, 2007

Dental Caries

Dental caries, also described as tooth decay, is a demineralization or an infectious disease caused by bacteria which damages the structures of teeth. The first signs of demineralization is a forming of small "white spot" (initial caries, incipient caries). It is not yet a cavity, the surface is still hard.

Bacteria are normally present in the mouth. The bacteria convert all foods especially sugar and starch into acids. The longer and more frequently sugar is in contact with teeth, the more likely this will happen. Sticky foods like toffee that take a long time to eat are major offenders. Bacteria, acid, food debris, and saliva combine in the mouth to form a sticky substance called plaque that adheres to the teeth. Plaque begins to accumulate on teeth within 20 minutes after eating (the time when most bacterial activity occurs). If this plaque is not removed thoroughly and routinely, tooth decay will not only begin, but flourish. The acids in plaque dissolve the enamel surface of the tooth and create holes in the tooth (cavities).

The resulting acidic levels in the mouth affect teeth because a tooth's special mineral content causes it to be sensitive to low pH. Depending on the extent of tooth destruction, various treatments can be used to restore teeth to proper form, function, and aesthetics, but there is no known method to regenerate large amounts of tooth structure.

Most cavities are discovered in the early stages during routine checkups. The surface of the tooth may be soft when probed with a sharp instrument. Cavities are usually painless until they grow very large inside the tooth and destroy the nerve and blood vessels in the tooth. If left untreated, a tooth abscess can develop. Untreated tooth decay also destroys the internal structures of the tooth (pulp) and ultimately causes the loss of the tooth.

Wednesday, January 31, 2007

Teeth Functions

Teeth are part of digestive system that are very important, because teeth help stomach to work by making foods into pieces, so that stomach will digest them easily. There are some teeth kinds and every tooth has special function :
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  1. Incisor
    It is the sharp, chisel-shaped front teeth (four upper, four lower) used for cutting food. Incisor located on front side of mouth bones upper and lower. There are no cusps on the tooth. Instead, the surface area of the tooth used in eating is called an incisal ridge or incisal edge.

  2. Canine
    This tooth kind is shaped like point (cusp). The location of the canines reflect their dual function as they complement both the premolars and incisors during mastication, commonly known as chewing. The most common action of the canines is tearing of food.

  3. Premolar
    This tooth has two pointed cusps on their biting surface and sometimes referred to as bicuspids. The function of this premolar is similar to that of canines in regard to tearing being the principal action during mastication, commonly known as chewing.

  4. Molar
    Molar is used for grinding, this tooth has several cusps on the biting surface.

Tuesday, January 23, 2007

Tooth Anatomy

Image Hosted by ImageShack.usTooth 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:
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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