odontogenesis

Question 1

odontogenesis

Answer 1

2) bud stage
3) cap stage
4) bell stage
–
5) crown/maturation stage

Question 2

timeline of development

Answer 2

1) 42-48 days
- dental lamina formation
2) 55-56 days
- bud stage of deciduous incisors, canines, molars
3) 14 weeks
- bell stage for deciduous, bud for permanent
4) 18 weeks
- dentin and functional ameloblasts in deciduous teeth
5) 32 week
- dentin and functional ameloblasts in permanent teeth

Question 3

initiation stage

Answer 3

1) formation of a continuous horseshoe shaped band of thickened epithelium
- stratified squamous
2) primary oral epithelium / primary epithelial band
3) each band of epithelium give rise to the dental lamina
4) dental placode inside DL
- initiation knot - transient signaling center
- primary oral epithelium presents odontogenic potential

Question 4

bud stage

Answer 4

1) dental lamina grows into the ectomesenchyme
2) tooth bud formed by epithelial cells
3) condensation of ectomesenchymal cells around the epithelial bud
- now assumes odontogenic potential

Question 5

early cap stage

Answer 5

1) the enamel organ
- outer enamel epithelium (glycogen)
- inner enamel epithelium (glycogen)
-stellate reticulum (glycosaminoglycans)
2) dental papilla and dental follicle
3) inner enamel epithelium
- ameloblasts
4) dental papilla
- dental pulp and odontoblasts
5) dental follicle
- cementoblasts, PDL, and alveolar bone proper
—
this is called the “tooth germ”
- enamel organ, dental papilla, dental follicle

Question 6

advanced cap stage

Answer 6

1) formation of enamel knot
- clusters of nondividing epithelial cells
- signaling and pattern formation of cusps
2) signal center that represents a organizational center which orchestrates cuspal morphogenesis

Question 7

cap to bell stage

Answer 7

1) primary enamel knot disappears and secondary enamel knots form
- at future locations of the cusps in premolars and molars
2) it is a signaling center

Question 8

bell stage

Answer 8

1) shape of the crown is established
2) the enamel knot disappears
2) formation of stratum intermedium
4) dental lamina begins to break up into discrete islands of epithelial cells (of serres)
5) formation of cervical loop
- root formation
6) mineralization starts
- amelogenesis (ameloblasts)
- dentinogenesis (odontoblasts)

Question 9

bell stage formation of permanent tooth

Answer 9

1) successional lamina arises from the dental lamina of the deciduous teeth (incisors, canines, and pre-molars)

Question 10

crown and maturation stage

Answer 10

1) increase minerals
2) increase size
3) maturation of crystals
4) completion of the crow formation

Question 11

how is tooth type determined

Answer 11

1) field model
2) tooth family

Question 12

field model genetic factors

Answer 12

1) presumptive incisor mesenchyme
- Msx-1, Msx-2, Alx-3
2) presumptive canines and premolar region
- Dlx1/2, Msx-1
3) presumptive molar region
- barx-1 and dlx-1/2

Question 13

anodontia (partial or complete)

Answer 13

1) absence of permanent or primary teeth that commonly include permanent third molar, maxillary lateral incisors, or second premolar
2) hereditary, endocrine, systemic disease, excess radiation that prevents tooth germ formation

Question 14

supernumerary tooth

Answer 14

1) development of one or more extra teeth that are commonly found between the permanent maxillary central incisors (mesiodens) distal to third molars, and premolar region
2) hereditary with extra tooth germ formation from persisting dental lamina clusters