Timing and sequencing of dental development

• Dental development occurs over a long time: 6 weeks in utero to late teenage years
• Dental development includes

  • Calcification
  • Eruption and emergence
• Tooth calcification


  Can be studied histologically, radiologically, and clinically
• Radiological assessment of tooth calcification

  1. Formation of dental crypt

  2. Calcification of cusps

  3. Calcification of crown

  4. Calcification of roots

  5. Emergence

  6. Closure of the apical canal of roots
• Sequence of primary tooth calcification


  • 51, 61, 71, 81
  • 54, 64, 74, 84
  • 52, 62, 72, 82
  • 73, 83, 53, 63
  • 55, 65, 75, 85
• Variability in tooth calcification


  • Related to individual, sex, ethnicity
  • Individuals: agenesis (non-development of a tooth)
  • Sex: females get 2° teeth earlier than males; crowns smaller, roots shorter
  • Ethnicity: Indigenous Australians & Africans - sequence of development compared to Europeans
• Tooth emergence


  • Movement of a developing tooth initiated by initial formation of the root
  • Appearance of tooth in the oral cavity
• Twins have later emergence of primary teeth than singletons
• Variability in tooth emergence

  • Timing and/or sequence
  • Within and between populations
• General factors affecting tooth emergence

  • Socio-economic status
  • Physical status
  • Genetic conditions
  • Endocrine conditions
  • Delayed tooth eruption/emergence
• Local factors affecting tooth emergence

  • Premature extraction of primary teeth
  • Early extraction of 6 or 7 affects 8
  • Amount of space - leeway space
  • Crowding, inclination and obstacles e.g. supernumerary teeth, cysts