5.2 Teeth: Structure, Types, Functions, and Dental Formula

1. Structure of a Tooth

1.1 Main Anatomical Parts

• Crown: Visible part above gum line, covered by enamel.
• Neck (Cervix): Where crown meets root, at gum line.
• Root: Embedded in jawbone, anchors tooth.

1.2 Layers of a Tooth

• Enamel: Outermost layer of crown; hardest substance in body; protects tooth.
• Dentin: Bone-like material beneath enamel/cementum; forms bulk of tooth; sensitive.
• Cementum: Covers root; anchors tooth to jawbone.
• Pulp: Innermost part (pulp chamber, root canals); contains blood vessels, nerves; nourishes dentin, provides sensation.

1.3 Supporting Structures

• Periodontal Ligament (PDL): Connects cementum to jawbone; shock absorber.
• Gingiva (Gums): Soft tissue around teeth; protective seal.
• Alveolar Bone: Part of jawbone supporting tooth roots.

2. Functions of Different Types of Teeth

• Incisors (8): Front teeth; chisel-shaped; for cutting and biting.
• Canines (4): Pointed; for tearing and piercing tough foods.
• Premolars (Bicuspids) (8): Two cusps; for tearing and crushing.
• Molars (12): Large, broad, flat surfaces; for grinding and mashing food.

3. Dental Formula of an Adult

• Represents number of each tooth type in one half of upper and lower jaws.
• Formula: 2(I 2/2, C 1/1, PM 2/2, M 3/3) = 32
  • I: Incisors
  • C: Canines
  • PM: Premolars
  • M: Molars
• Total 32 permanent teeth (including wisdom teeth).