Dentition in Humans

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Dentition in Humans

• MUNALI BOYS HIGH SCHOOL Muleba A. MBiology 10

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Structure of a tooth

• External parts of a tooth
• Crown, part above gum. Has thick outer layer
  called enamel.
• Neck, part between crown and root. Provides
  direct contact with gum.
• Root, part within the jaw. Forms the cover called
  cementum.

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Internal Parts of a Tooth

• Enamel, Dentine, Pulp Cavity, Blood Vessels,
  Nerves, and Fibres.
• See following slides for details

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NERVES

• Nerves are found in the pulp cavity
• They make the tooth more sensitive

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Blood Vessels

• Blood vessels are found in the pulp cavity.
• Blood vessels supply a tooth with oxygen and
  nutrients.

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FIBRES

• Connect the tooth to the gum
• They hold the tooth in its socket, but permit it
  to move slightly and cushion it from excessive
  jarring when it hits something hard.

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ENAMEL

• Enamel is the surface of a tooth, part of which
  is exposed
• Made up of a hard substance that contains calcium
  phosphate.

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DENTINE

• Dentine is the bone like structure that surrounds
  the pulp cavity.
• Made up of tiny channels containing living cells
• Makes the tooth sensitive.

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PULP CAVITY

• Pulp cavity is in the middle of a tooth.
• It has soft tissues containing blood vessels and
  nerves.

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TYPES OF TEETH

• INCISORS
• Shaped like chisels and used for cutting
• CANINE
• Shaped like daggers and used for cutting
• MOLARS AND PREMOLARS
• Flat surface used for grinding

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TOOTH DECAY

• After a meal, bacteria in the mouth feed on any
  sugar present and turn it into acids.
• Acids eats the teeth and cause cavities.

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PREVENTION OF DECAY

• Visit the dentist regularly.
• Brush the every after a meal.
• Avoid sweet foods.
• Do not open bottles using teeth.

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Review Questions

• The crown or exposed part of a tooth, consists of
  a very hard material covering the main substance
  of a tooth. What name is this part?
• State the functions of the following enamel,
  dentine, pulp cavity, blood vessels nerves, and
  fibres
• How can you prevent tooth decay?