Anatomy-Dental Structures



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CROWN

The crown is the exposed surface above the gum line on the normal adult tooth. The crown is covered with enamel.

ENAMEL

Enamel covers the crown of the tooth. It is the hardest substance in the body. It is 90% mineral and normally very smooth. The enamel is completely formed in the unerupted tooth at 8 weeks of age, as hard as it will ever be and irreplaceable, whether complete or incomplete, for the entire life of the animal.

DENTIN

Dentin is the layer immediately beneath the enamel. The dentin extends from the crown to the apex of the tooth. It is softer than the enamel and only 70% mineralized. The dentin is constantly formed throughout life and provides the support of the tooth. Connections between the dentin and the bone of the jaw hold the tooth in place. Cementum covers the dentin beneath the gum line.

CEMENTO-ENAMEL JUNCTION

The cemento-enamel junction is located where the enamel stops and the root of the tooth begins. The root of the tooth is covered with cementum, which binds the tooth into place. The periodontal ligaments bridge the junction between the cementum and the bone of the jaw. The periodontal ligament is a shock absorber for the tooth. The cemento-enamel junction is also called the cervix or neck of the tooth. It is located at the base of the gum tissue and is the most common location of cavities in dogs and cats. Cervical caries (cavities) are a serious problem that is common in cats and can result in pain, loss of appetite and loss of the tooth.

PULP

The pulp chamber is in the center of the tooth. The pulp is composed of nerves, blood vessels and the cells that produce the dentin. It is responsible for feeling in the tooth – all sensation in the tooth whether heat, cold or trauma is perceived as pain. The pulp lives in the PULP CHAMBER that extends from the apex of the tooth to the level of the crown. The pulp below the level of the crown is called the PULP CANAL or ROOT CANAL that extends below the neck of the tooth.

PERIODONTAL LIGAMENT

The periodontal ligament attaches to the cementum and to the bone in the socket (alveolar bone) holding the tooth in place. The periodontal ligament can regenerate if damaged but it heals slowly.

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CUSP

A cusp is a point or tip of the crown or the tooth.

MANDIBLE

The lower jaw bone.

MAXILLA

The upper jaw bone.

ALVEOLAR BONE

The bone of the upper or lower jaw that forms the socket of the tooth or alveolar socket.

GINGIVA

Gingiva is gum tissue. This tissue stops at the mucogingival line, which is the junction of the lining of the mouth (MUCOSA) with the gum tissue. The gum tissue is attached to the cementum of the root of the tooth at the cemento enamel junction. The gum tissue extends past this attachment onto the tooth a short distance.

CEMENTUM

Cementum is the covering of the root of the tooth. It is bound to the dentin and serves as a point of attachment of the periodontal ligament to the alveolar bone. The cementum cements the tooth into the socket.

APEX OF TOOTH

The apex of the tooth is the part of the tooth that is embedded the deepest into the bone. It is the tip of the tooth opposite the crown. The apex is the location where the nerves and blood vessels enter the tooth. The apex is a point that is commonly infected in a tooth causing an “apical abscess”.

CERVICAL LINE

The cervical line is also the cemento-enamel junction. It is the location of cavities.

PRIMARY TEETH

Primary teeth, deciduous teeth, baby teeth, and milk teeth are all names for the first teeth that grow and are replaced later by the adult teeth.

PLAQUE

Plaque is a bacterial mass that attaches itself to the tooth surface. Plaque is colorless and cannot be seen unless in large amounts. Plaque is the matrix that becomes calcified to form tartar. Plaque removal will prevent tartar. Plaque is the initial stage of dental disease and causes gingivitis. You may know plaque as the “sweaters” that cover your teeth after a long period of not brushing.

TARTAR

Tartar is calcified plaque and is also called calculus. Tartar can be supra-gingival (above the gum-line) or sub-gingival (below the gum-line) and causes inflammation and resultant recession of the bony tissue of the tooth socket. This leads to deepening of the gingival sulcus and periodontitis.

CARIE

A cavity in a tooth, more common in cats and usually occurs at the cemento-enamel junction.

 

SELF EVALUATION

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Please label the anatomical drawing:

  1. What is the hardest part of the tooth?
  2. Where does the plaque accumulate?
  3. What holds the tooth into the socket?
  4. What must happen before a tooth becomes loose?
  5. Does a tooth have feelings?
  6. What tooth in the dog is most commonly abscessed? Why?
  7. What is a cusp?
 

Please label the drawing below by writing the name of the anatomical part next to the corresponding number.
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