Preclinical Paediatrics · MU Sofia

4. Tooth germ - physiological stages in the development of teeth.

Walks through the physiological stages of tooth germ development, starting with initiation, where the primary epithelial band, vestibular lamina and dental lamina form from oral ectoderm and ectomesenchyme. It then covers proliferation and tooth bud formation, histodifferentiation with its epithelial layers and the enamel knot, enamel cord and enamel niche, morphodifferentiation of the enamel organ, dental papilla and follicle, apposition of enamel, dentin and cementum, maturation and eruption. The note also sets out the morphological stages from bud to bell.

Inside: 7 sections · 2 labelled pictures · 15 flashcards · 5 min

Topic 4 of 40 in the MU Sofia syllabus for Preclinical Paediatrics (Dental Medicine, Year 3). The free AceMed note covers it in 7 sections, about 746 words (5 min of reading), with 15 flashcards.

In this note

  1. TOOTH GERM - PHYSIOLOGICAL STAGES IN THE DEVELOPMENT OF TEETH.
  2. Proliferation
  3. Histodifferentiation
  4. Morphodifferentiation
  5. Apposition
  6. Maturation
  7. Eruption

TOOTH GERM - PHYSIOLOGICAL STAGES IN THE DEVELOPMENT OF TEETH.

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
  • Maturation
  • Eruption

Initiation

  • Newly formed stomodeum is lined by a primitive 2 or 3-cell thick layered epithelium covering an embryonic tissue that is now called Ectomesenchyme (neural crest cells+ mesenchyme)
  • Ectomesenchyme consists of a few spindle shaped cells separated by a gelatinous ground substance
  • Formation of primary epithelial thickening dental lamina, tooth bud and cap, bell stage cannot take place without dentally active ectomesenchyme which becomes concentrated in regions of presumptive tooth development
  • Inner epithelium of enamel organ induces ectomesenchyme of dental papilla to become orientated towards the intervening basal lamina and differentiate into odontoblasts

Stages of Initiation:

  • Primary Epithelial Band
  • Continuous band of thickened epithelium forms around the mouth in presumptive upper and lower jaws ↳ change in orientation of mitotic spindle & cleavage plane of dividing cells
  • Bands are roughly horseshoe shaped and correspond to position of future dental arches of jaw
  • Each band of epithelium gives rise to Vestibular Lamina and Dental lamina
  • Vestibular lamina (lip furrow band)
  • Vestibule forms as a result of proliferation of vestibular lamina into ectomesenchyme
  • Cells rapidly enlarge and then degenerate to form a cleft that becomes the vestibule between the cheek and tooth bearing area
  • Dental lamina
  • Located orally to vestibular lamina
  • Within dental lamina, continued and localized proliferative activity leads to formation of a series of epithelial outgrowth into ectomesenchyme at sites corresponding to positions of future primary teeth

Continue reading free

The whole note, all 7 sections, is free with an AceMed account, with its 15 flashcards. Premium adds flashcard recall, highlights and Ask AI.

Start freeAlready a member? Open the note