Study Notes on the Oral Cavity and Human Dentition

Introduction to the Oral Cavity

  • Presented by Dr. Kornelija Sfera

Intended Learning Outcomes

  • Relate the oral cavity to the surrounding structures of the head and neck
  • Compare and contrast the basic traits of the two sets of human dentition
  • Apply the rules of the FDI tooth numbering system to permanent and primary dentitions

Boundaries of the Oral Cavity (Recapitulation)

  • Anterior: Lips
  • Lateral: Cheeks
  • Posterior: Palatoglossal fold
  • Superior: Palate
  • Inferior: Floor of the mouth

Anatomy of the Oral Cavity

Regions and Sections

  • Oral Cavity Proper: The main space where food is ingested, contains the gums and teeth
  • Vestibule: The space between the lips and cheeks externally, and the gums and teeth internally
  • Soft Palate: The muscular part at the back of the roof of the mouth
  • Hard Palate: The bony front part of the roof of the mouth
  • Tongue: A muscular organ crucial for taste, swallowing, and speech

Midsagittal Cross-Section of the Head

  • Visual representation showing the relationship of oral cavity to adjacent structures
  • Key components include:
    • Pharynx
    • Nasal cavity
    • Nasopharynx
    • Oropharynx
    • Laryngopharynx
    • Cricoid cartilage
    • Uvula
    • Lingual tonsils
    • Epiglottis
    • Hyoid bone

Oral Cavity Relations

  • Relations with Paranasal Sinuses:
    • Frontal Sinus: Located above the eyes, drains into the nasal cavity
    • Sphenoid Sinus: Located behind the eyes, drains posteriorly
    • Ethmoid Sinus: Located between the eyes, consists of multiple air cells
    • Maxillary Sinus: Below the eyes, drains into the middle nasal meatus
    • Relationship to the nasal cavity is significant for understanding oral and sinus pathologies

Oroantral Communication

  • Pertains to the roots of maxillary posterior teeth in close relation to the maxillary sinus floor
  • Possible Outcomes:
    • Iatrogenic communication may occur post-extraction
    • Untreated communication can lead to maxillary sinusitis

Human Dentition

Overview

  • Humans possess two sets of teeth:
    1. Primary Teeth (also known as baby, deciduous, or milk teeth)
    • Present from about 6 months of age until around 12 years
    1. Permanent Teeth (adult teeth)
    • Begin appearing around 6 years of age and last throughout adulthood

Mixed Dentition

  • Describes the transitional period (around 6 to 12 years) when both primary and permanent teeth coexist in the mouth

Primary Dentition

  • Represents the first set of human teeth; all primary teeth are eventually replaced by permanent teeth
  • Total count of primary teeth: 20
    • Arrangement: 5 in each quadrant of the dental arch

Permanent Dentition

  • Full set comprises 32 permanent teeth
    • 8 in each quadrant of the oral cavity

Differences Between Primary and Permanent Dentition

  • Tooth Anatomy Comparison:
    • Central Incisors
    • Lateral Incisors
    • Cuspids (Canines)
    • Premolars and Molars differ in structure and count
  • Characteristics:
    • Number: Primary have 20, permanent have 32
    • Color: Primary teeth generally appear whiter
    • Shape: Permanent teeth are more robust and complex
    • Size: Permanent teeth are larger overall than primary teeth

Tooth Development Timeline

Timeline of Eruption

  • Primary Teeth Eruption:

    • Central Incisors: 6-10 months
    • Lateral Incisors: 8-13 months
    • Cuspids (Canines): 13-19 months
    • First Molars: 16-23 months
    • Second Molars: 23-33 months

  • Permanent Teeth Eruption:

    • Central Incisors: 6-8 years
    • Lateral Incisors: 7-9 years
    • Canines (Cuspids): 9-12 years
    • First Molars: 11-13 years
    • Second Molars: 11-13 years
    • Third Molars (Wisdom Teeth): 17-21 years

Tooth Identification Using FDI Notation System

Overview of FDI Notation

  • Permanent Teeth:
    • Two digits notation system
    • First digit indicates quadrant (1-4); second digit indicates tooth position relative to midline (1=central incisor, 8=third molar)

Primary Teeth Notation

  • Similar two digits notation:
    • First digit indicates quadrant (5-8); second digit indicates tooth
    • Teeth are numbered starting from the midline
    • Notations for primary teeth:
    • '1' = Central Incisor
    • '5' = Second Primary Molar

References

  • Illustrated Anatomy of the Head and Neck: Fehrenbach MJ, Herring SW; Elsevier 2017, 5th ed, Chapter 2, pg. 20
  • Oral Anatomy, Histology and Embryology: Berkovitz BK, Holland M, Moxham; Mosby Elsevier 2018, 5th ed, Chapter 2, pgs. 13-15
  • Netter’s Head and Neck Anatomy for Dentistry: Norton NS, Elsevier 2017, 3rd ed, Chapter 13, pgs. 348-349, 354, 357-359
  • Relevant YouTube Links for visual understanding of tooth differences and erruption processes.