Tooth Development Flashcards
(45 cards)
what is the pattern of tooth eruption of the primary dentition with timeline
- mandibular central incisors: 5-8 mo.
-maxillary central incisors: 6-10 months
-mandibular lateral incisors: 7-10 mo. - maxillary lateral incisors: 8-12 months
- mandibular canine: 16-20 months
- maxillary canine: 16-20 months
- mandibular first molars: 11-18 months
- maxillary first molars: 11-18 months
- mandibular second molars: 20-30 months
- maxillary second molars: 20-30 months
when does calcification of the permanent dentition begin
- central incisors: 3-4 months
- maxillary lateral incisors: 10-12 months
- mandibular lateral incisors: 3-4 months
- canines: 4-5 months
- first premolars: 18-24 months
- second premolars: 24-30 months
- first molars: birth
- second molars: 30-26 months
- maxillary third molars: 7-9 years
- mandibular third molars: 8-10 years
when is the crown completely calcified in permanent dentition
- central incisors: 4-5 years
- lateral incisors: 4-5 years
- canines: 6-7 years
- first premolars: 5-6 years
- second premolars: 6-7 years
- first molars: 30-36 months
- second molars: 7-8 years
when is the first sign of tooth development in utero
6-7 weeks
when do deciduous teeth begin to calcify in untero
13-20 weeks
how long in utero for all deciduous teeth have begun to calcify
18-20 weeks
when do deciduous teeth erupt
6-30 months
what part of the tooth is the first to calcify
the crown
what gene is responsible for tooth development in the dental mesenchyme stage
msx1
what are the stages of tooth development in order
- crown formation
- root formation
- supporting structures
what are the steps in crown formation
-initiation
- bud stage
-cap stage
- bell stage
- enamel and dentin formation
describe the primary epithelial band
-horseshoe shaped
- correspond to future dental arches
what does the primary epithelial band give rise to
dental lamina and vestibular lamina
what is expressed in the epithelium where the tooth bud would form
SHH
what is expressed in the mesenchyme where the tooth bud would form
Pax9
describe the initiation of tooth development
- placode formation- epithelial thickening
- epithelial outgrowth into the mesenchyme
- initial odontogenic potential lies in the epithelium subsequently shifts to mesenchyme - the neural crest mesenchyme induces the oral ectoderm to become the dental lamina
what happens in the bud stage
-epithelial cells show no major changes
- Shh, Lef-1 and Eda-Edar involved in placode formation
- mesenchyme beneath starts to condense by the factors secreted by the epithelium
- cross talk between the epithelium and the mesenchyme
-odontogenic potential in the epithelium
what happens in the cap stage
- epithelium proliferates, mesenchyme continue to condense. looks like cap sitting on a ball of mesenchyme
- tooth germ: enamel organ and dental papilla
what is the bud to cap stage regulated by
signaling molecules and transcription factors
what does the enamel organ become
enamel of the tooth
what does the dental papilla form
dentin (outer) and pulp ( inner)
what does the dental follicle or dental sac differentiate into
supporting structures such as cementum/ periodontium/ alveolar bone proper
what is the enamel knot
a key signaling center consisting of cluster of non dividing cells that determine cusp formation
describe cap stage histodifferentiation
-cells in the enamel organ synthesize glycosaminoglycans in the ECM. hydrophilic and pull water in to the enamel organ
- increase in fluid volume forces the cells apart leading to formation of star shpaed stellate reticulum cells
