Macroscopic structure of the teeth, fixation, gingivodental junction, innervation and vascular supply

1. External Anatomy

• Crown:
  • Visible part above the gumline.
  • Covered with enamel.
• Root:
  • Embedded in the jawbone.
  • Covered by cementum.
  • Anchored by the periodontal ligament.
• Neck (Cervix):
  • Junction between crown and root.
  • Encircled by the gingiva (gums).

2. Surfaces of the Teeth

• Occlusal Surface: Chewing surface of molars/premolars.
• Incisal Edge: Cutting edge of incisors.
• Mesial: Surface facing the midline of the dental arch.
• Distal: Surface facing away from the midline.
• Lingual/Palatal: Inner surface facing the tongue/palate.
• Buccal/Labial: Outer surface facing the cheeks or lips.

3. Types of Teeth

• Incisors: Cutting function (8 total).
• Canines: Tearing function (4 total).
• Premolars (Bicuspids): Crushing and grinding (8 total).
• Molars: Heavy grinding (12 total, including wisdom teeth).

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Fixation of Teeth

1. Periodontium: Structures that fix the tooth in place:
   • Cementum: Mineralized tissue covering the root.
   • Periodontal Ligament (PDL):
     • Dense connective tissue anchoring cementum to alveolar bone.
     • Absorbs mechanical stresses during chewing.
   • Alveolar Bone:
     • Surrounds and supports the tooth socket.
     • Trabecular bone in the jaw providing stability.
   • Gingiva (Gums):
     • Soft tissue surrounding the teeth and covering the alveolar bone.
     • Acts as a barrier against bacterial invasion.

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Gingivodental Junction

1. Definition:
   • The area where the gingiva meets the tooth surface, providing a protective seal.
2. Key Components:
   • Free Gingiva:
     • Unattached tissue around the tooth.
     • Forms the gingival sulcus (1-3 mm depth in healthy conditions).
   • Attached Gingiva:
     • Firmly bound to the underlying alveolar bone.
   • Junctional Epithelium:
     • Specialized epithelial tissue that forms a tight seal with the tooth surface.
     • Prevents bacterial penetration into deeper tissues.
3. Clinical Relevance:
   • Inflammation of the gingivodental junction leads to gingivitis or periodontitis.
   • Loss of junctional epithelium attachment contributes to periodontal disease.

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Innervation of Teeth

1. Sensory Innervation:
   • Maxillary Teeth (Upper Jaw):
     • Supplied by the superior alveolar nerves (branches of the maxillary nerve - CN V2).
     • Includes anterior, middle, and posterior superior alveolar nerves.
   • Mandibular Teeth (Lower Jaw):
     • Supplied by the inferior alveolar nerve (branch of the mandibular nerve - CN V3).
2. Periodontal and Gingival Innervation:
   • Supplied by branches of the trigeminal nerve (CN V).
   • Conveys pain, pressure, and proprioception.

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Vascular Supply of Teeth

1. Arterial Supply:
   • Maxillary Teeth:
     • Supplied by branches of the maxillary artery:
       • Anterior, middle, and posterior superior alveolar arteries.
   • Mandibular Teeth:
     • Supplied by the inferior alveolar artery (branch of the maxillary artery).
2. Venous Drainage:
   • Venous drainage parallels the arterial supply.
   • Drains into the pterygoid venous plexus.
3. Periodontium and Gingiva:
   • Supplied by anastomoses between:
     • Superior and inferior alveolar arteries.
     • Facial and lingual arteries.
4. Clinical Relevance:
   • Infections in the oral cavity can spread via venous drainage, potentially leading to systemic complications.