Embryology of tooth development part 1

Question 1

What branchial arch do teeth develop from

Answer 1

first

Question 2

What occurs in the reciprocal induction of dentiogenesis and amelogenesis

Answer 2

Downward and forward growth of 1st branchial arch ectomesenchyme brings it into contact with ‘oral’ epithelium
The oral epithelium has an instructive effect on the ectomesenchyme leading to odontoblast differentiation
Subsequently the ectomesenchyme feeds back to the OE to regulate patterning and amelogenesis

Question 3

What are the stages of dentinogenesis

Answer 3

Odontoblast differentiation
Formation of mantle dentine 
Formation of primary dentine 
Formation of secondary dentine 
Formation of tertiary dentine

Question 4

What does the primary epithelial band split into

Answer 4

Vestibular lamina and dental lamina

Question 5

What does dental lamina do

Answer 5

Leads to tooth development

Question 6

What are the stages involved in tooth development

Answer 6

Bud, cap, bell and crown stage

Question 7

What happens in the bud stage

Answer 7

• Epithelium of the dental lamina begins to form a ‘bud’ into underlying ectomesenchyme
• Forms inside upper and Lower jaws

Question 8

What happens in the cap stage

Answer 8

Stage of cellular proliferation

• The epithelial bud continues to grow to form a ‘cap’ shaped structure - this is known as the dental/ enamel organ
• Ectomesenchymal condensations form around the epithelial buds which give rise to the dental papilla and dental follicle

Question 9

What does the dental papilla make

Answer 9

Dentine and the pulp

Question 10

What does the dental follicle contain

Answer 10

Blood vessels and nerves

Question 11

What makes up the tooth germ

Answer 11

Dental organ + Dental papilla + Dental follicle

Question 12

What happens in the bell stage

Answer 12

Stage of histodifferentiation and morphogenesis
- The dental organ grows into a bell shape
- Cell of the dental organ differentiate, depending on their new function they will fall into one of the four cell groups: inner enamel epithelium, outer enamel epithelium, stratum intermedium, stellate reticulum
These work together to develop the enamel layer of the tooth - amelogenesis

Question 13

What happens in the crown stage

Answer 13

Stage of development of the dental hard tissues

• Differentiation of odontoblasts from the dental papilla and commencement of formation of a mineralised dentine matrix
• Followed immediately by the commencement of amelogenesis by ameloblasts which develop from the internal enamel epithelium

Question 14

What happens in root formation and cementogenesis

Answer 14

• Once the crown form is established, the cervical sheath grows downwards as ‘Herwigs Root Sheath’ to define the shape of the root