2b Odontogenesis

Question 1

What stage is tooth shape determined?

Answer 1

between bud and cap stage

Question 2

What transciption factors determine posterior teeth?

Answer 2

Dix1/2 and Barx-1

Question 3

What transcription factors determine anterior teeth

Answer 3

Msx-1/2 and Alx-3

Question 4

What happens to the reduced ameloblasts and other remnants of the enamel organ (OEE, stellate reticulum and stratum intermedium)?

Answer 4

Start to fuse to become the reduced enamel epithelium

Question 5

What is the role of reduced enamel epithelium?

Answer 5

• Protection of enamel surface form
  ○ Resorption
  ○ Prevention of cementum formation
  
  • Provide an epithelial lines pathway for eruption
    Form the initial junctional epithelium

Question 6

In what position relative to the primary tooth, is the successional lamina going to develop?

Answer 6

lingual

Question 7

What common developmental disturbances are seen in the initiation stage?

Answer 7

• Anodontia
  ○ All teeth missing
  ○ Extremely rare
  ○ Possibly to do with PITX being formed
  
  • Oligodontia
    ○ More than 6 teeth are missing
    ○ This disturbance happens at the initiation stage
    ○ Something going wrong with Msx-1, Pax-9 or Axin2 in development
  • Hypodontia
    ○ One or a few missing teeth (except 3rd molars)
    ○ 2-10% of population
    Msx-1, Pax9
• Supernumeracy of tooth/teeth (over expression of msx-1 and pax-9)

Question 8

What common developmental disturbances are seen in the bud stage?

Answer 8

• Microdontia
  ○ Abnormally small teeth
  ○ Clinical - need to fill the space
  
  • Macrodontia
    ○ Abnormally large teeth
    Clinical - need to do some extractions

Question 9

What common developmental disturbances are seen in the cap stage?

Answer 9

• Dens in dente
  ○ Enamel organ invaginates into the dental papilla
  ○ Commonly affects the permanent maxillary lateral incisor
  ○ Get this deep lingual pit forming
  ○ Probably need endodontic treatment
  
  • Fusion
    ○ Union of 2 teeth resulting in 1 large tooth
    ○ Orthodontic treatment
  • Germination
    ○ Tooth germ tries to divide and you get a large single root with one pulp cavity and 2 teeth
    Orthodontic treatment