Preclinical Paediatrics · MU Sofia

5. Tooth germ - morphological stages in the development of the enamel organ.

Covers the origin of tooth germs from oral ectoderm and ectomesenchyme, then moves through the dental lamina and the bud, cap and bell stages of the enamel organ. It describes the enamel knot, enamel cord and enamel niche, the cell layers of the enamel organ, and the cervical loop and Hertwig's root sheath. It ends with the formation of the permanent dentition, crown pattern determination, and the roles of the inner epithelium, dental papilla, dental follicle, stellate reticulum and stratum intermedium.

Inside: 14 sections · 4 labelled pictures · 14 flashcards · 11 min

Topic 5 of 40 in the MU Sofia syllabus for Preclinical Paediatrics (Dental Medicine, Year 3). The free AceMed note covers it in 14 sections, about 1,604 words (11 min of reading), with 14 flashcards.

In this note

  1. TOOTH GERM - MORPHOLOGICAL STAGES IN THE DEVELOPMENT OF THE ENAMEL ORGAN.
  2. Two Stages of Development
  3. Dental lamina
  4. Bud Stage
  5. Bud to Cap Transition
  6. Cap Stage
  7. Bell Stage
  8. Early Bell Stage
  9. Advanced Bell Stage
  10. Functions of the inner epithelium
  11. Functions of the dental papilla
  12. Dental follicle
  13. Functions of the stellate reticulum
  14. Stratum intermedium

TOOTH GERM - MORPHOLOGICAL STAGES IN THE DEVELOPMENT OF THE ENAMEL ORGAN.

Teeth have ectodermal and mesodermal origin

  • Mesoderm is the 4th embryonic leaf: ectomesenchyme is also involved
  • Ectomesenchyme epithelium is a combination of neural crest cells and mesenchyme

In tooth development, interaction of oral ectoderm and ectomesenchyme initiate the process

Cellular interaction leads to formation of dentin, enamel, cementum and the crown

Two Stages of Development

Morphological Stages:

  • Dental lamina
  • Bud Stage
  • Cap Stage
  • Early Bell Stage
  • Advanced Bell Stage
  • Formation of Enamel and Dentin Matrix

Physiological Stages:

  • Initiation
  • Proliferation
  • Histodifferentiation
  • Morphodifferentiation
  • Apposition-Mineralization
  • Maturation
  • Eruption

Dental lamina

  • One of two subdivision of primary epithelial band, other being vestibular lamina
  • Dental lamina is located orally to vestibular lamina.
  • Within dental lamina, continued and localized proliferative activity leads to formation of a series of epithelial outgrowths into ectomesenchyme at sites corresponding to positions of future primary teeth
  • In upper and lower dental lamina are formed 10 proliferations. Process called “tooth bud formation”. Beginning of tooth development

Teeth develop from three types of cells:

  • Oral Epithelial Cells
  • Mesenchymal Cells
  • Neural Crest Cells: ectomesenchymal cells

Next Development of Dental Lamina

  • Begin localized proliferations:
  • Early in medial part: incisors
  • Then in lateral part: canines and molars
  • In the upper and lower dental lamina are formed 10 proliferations

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