Teeth Gastrointestinal System > Anatomy > Anatomy
TEETH
• Accessory digestive organs housed within the oral cavity.
• 32 permanent teeth in the adult, which replace the 20 deciduous teeth, (aka, milk teeth) that are lost during childhood.
4 PERMANENT TOOTH TYPES:
• Incisors, which slice and bite through foods
• Canines, which puncture foods
• Premolars, which crush and grind foods
• Molars, which also crush and grind foods
Regions of a tooth:
• Crown is the exposed portion
• Neck is the constricted region
• Root anchors the tooth in the jaw
Dental arches
• Teeth in anatomical position
• Quadrants along the sagittal plane:
- Upper (aka, maxillary) quadrants – right and left upper
- Lower (aka, mandibular) quadrants – right and left lower
Tooth Surfaces
• Vestibular surface
- Faces the lips and cheeks; the space between the teeth and overlying soft tissues is the vestibular cavity.
- Can also be called the labial or buccal surface, which depends on whether the tooth faces the lips or cheeks.
1 / 3 • Lingual surface
- Faces the tongue ("lingual" refers to the tongue)
• Occlusal surface
- Faces the tooth of the opposite jaw; it is where the teeth from the superior and inferior jaws meet.
- Occlusal surfaces of the premolars and molars have prominent ridges, called cusps, that mash the foods.
- Premolars typically have two cusps (and are therefore referred to as the bicuspids), and molars typically have 3-5.
• Mesial surface
- Faces the midline of the mouth
• Distal surface
- Faces away from the midline.
The mesial and distal surfaces of the teeth are collectively called proximal surfaces.
Anatomy of a molar:
• Alveolar socket (aka, tooth socket)
- Space within the jaw bone for the tooth.
- Comprises the connective tissues that attach the tooth to the bone
- Gingivae (aka, gums),are the outermost layer of the peridontium; they overlie the jawbone and attach to the neck of the tooth.
• Enamel
- Is the thick protective layer of the crown; the enamel is formed by calcium salts and is the hardest substance in the body.
• Dentin
- Surrounds the pulp cavity, which is a space within the tooth. Dentin comprises the majority of the tooth and is similar to bone tissue, but much harder; it protects the pulp cavity contents.
• Pulp
- Includes neurovascular structures
- Portion of the pulp that extends into the roots.
- Opening where neurovascular structures enter and exit the tooth to travel within the bone of the jaw.
• Cementum
2 / 3 - Comprises the outer protective cover of the root, and,
• Periodontal ligaments
- Connect the cementum of the root to the alveolar socket (to form a fibrous gomphosis joint).
Clinical correlations:
• Dental plaque comprises a thin layer of sugars, bacteria, and other materials that adhere to the teeth; flossing and brushing the teeth helps to prevent plaque build-up.
• Dental caries (aka, cavities) reflect decay of dental enamel and dentin by demineralizing acids, which are produced when bacteria metabolize dental plaque.
• Gingivitis refers to infection of the gingivae, in which the plaque accumulations, called calculus, detach the gums from the teeth.
If the calculus is not removed, periodontal disease (aka, periodondtis), may result.
• In periodontal disease, inflamed pockets of infection form between the teeth and gums, and trigger an immune response that leads to the erosion of the bone surrounding the tooth. Without treatment, periodontal disease causes tooth loss.
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