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Questions and Answers
When do deciduous (baby) teeth begin to develop?
What is ectomesenchyme tissue derived from?
Which of the following is not a stage of tooth morphogenesis?
What causes the cells within the dental lamina to proliferate and invaginate?
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Which tissue components are involved in tooth development?
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When do permanent teeth begin to develop?
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What is the third stage of tooth development?
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Which type of cells form the stellate reticulum in the cap stage of tooth development?
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What role do enamel knots play in tooth development?
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Where do ectomesenchymal cells mainly accumulate during the cap stage of tooth development?
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What event characterizes the Bell Stage of tooth development?
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What new cell type is formed between the stellate reticulum and inner enamel epithelium during tooth development?
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Study Notes
Odontogenesis (Teeth Development)
- Deciduous teeth develop in week 6-7 of in-utero life
- Permanent teeth develop in week 14 of in-utero life
- Permanent teeth have successional lamina, which is not present in deciduous teeth
Tooth Development Stages
- Teeth start to develop in week 6 from 2 tissue components: primitive oral epithelium (derived from ectoderm) and ectomesenchyme (derived from craniofacial neural crest cells)
- Primitive oral epithelium thickens, creating primary epithelial bands, one on each jaw
- Each primary epithelial band splits into two: inner/lingual dental lamina and outer/buccal vestibular lamina
Signal Proteins
- FGF, BMP, and EDA cause cells within the dental lamina to proliferate and invaginate, forming dental placodes (enlarged projections within the dental lamina)
Tooth Morphogenesis (Tooth Shape Formation)
- The interaction between epithelium and mesenchymal tissues goes through 3 stages: bud, cap, and bell
- During morphogenesis, the tooth undergoes different shape formations, resulting in various tooth shapes
Bud Stage
- Dental placode proliferates, forming a bud-like structure (tooth bud)
- Tooth bud attaches to oral epithelium by the dental lamina
- Ectomesenchymal cells cluster around the tooth bud, causing condensation of the ectomesenchymal cells (beneath the bud)
Cap Stage
- 3 different epithelial cells form: inner enamel epithelium, outer enamel epithelium, and stellate reticulum
- Inner enamel epithelium lines the inner enamel central depression
- Outer enamel epithelium lines the sides of the cap
- Stellate reticulum secretes glycosaminoglycans, attracting water and pushing on the cell membrane, turning them into a star shape
Enamel Knots
- Non-dividing cells within the enamel organ, acting as a signalling centre
- Regulate the formation of the cusps of the tooth
- The number and location of enamel knots determine the number and location of cusps
Bell Stage
- Enamel organ continues to grow
- The invagination (indent) in the cap deepens, forming the cervical loop
- The cervical loop is at each tip of the enamel organ (root-like shape)
- The cervical loop is where the inner and outer epithelium meet (at the root ends)
- Cells between the stellate reticulum and inner enamel epithelium differentiate into a new cell called stratum intermedium (spindle shape)
- Stellate reticulum starts to collapse
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Description
Learn about the timeline of deciduous and permanent tooth development during in-utero life, as well as the different tissue components involved in odontogenesis.
