eruption patterns of teeth

Question 1

what controls the speed of eruption?

Answer 1

• Genetic control
• Local environment factors may play a major role
• Requires development of the tooth support tissues and dento-gingival junction

Question 2

how must the teeth move in order to erupt into the oral cavity

Answer 2

• Teeth must move from the crypt
• Through alveolar bone
• Break epithelial integrity
• Erupt into the oral cavity

Question 3

what occurs during the pre-eruptive phase?

Answer 3

• Initiation of root formation stimulates dental follicle
  
  • dental follicle is surrounded by bony crypt
• Recruits multiple growth/ transcription factors/hormones Required for:
  
  • Osteoclastogenesis
  • Osteogenesis
    
    • Both required for tooth eruption

Question 4

what occurs during intra-osseous eruption?

Answer 4

• Spatially restricted removal of bone on the coronal side of the tooth (+1o tooth)
  
  • Removing bone / deciduous tooth
• Creates eruption pathway
• Tooth moves in occlusal direction
• Bone apposition in the apical follicle
  
  • Translocation of the tooth occlusally
• Bone also deposited in bucco-lingual aspect
  
  • Forming dento-alveolar process
• Bone formation increases dento-alveolar process

Question 5

what is the speed of intra-osseous movement determined by?

Answer 5

• genetic factors
• local environmental factors
  
  • crowding
  • disturbed bone remodelling
    
    • reduced osteoclast activity
  • obstacles
    
    • e.g. money / cysts
  • trauma
  • early loss of primary teeth

Question 6

how does the tooth penetrate the mucosa?

Answer 6

Reduced enamel epithelium fuses with oral epithelium:

• forming epithelial plug

central cells degenerate leaving epithelial lined canal for eruption

Question 7

what occurs during supra-osseous eruption?

Answer 7

• Continues to erupt
  
  • At a speed of 25-75 microns/day
• All movement during night
• Active eruption stops once occlusal contact made
• Drift continues to occur through remodelling of PDL
  
  • PDL contains chemical mediators required to stimulate tooth movement

Question 8

what happens to the roots of the deciduous teeth?

Answer 8

are resorbed

Question 9

what are the gubernacular canals?

Answer 9

• directional pathways
• between permanent tooth germ and apex of deciduous tooth
  
  • directional pull for permanent teeth to erupt apical to their predecessor
  • contain remnants of dental lamina and connective tissue
• canal widened by bone resorption during eruption

Question 10

in what order to the deciduous teeth erupt?

Answer 10

1. A
2. B
3. D
4. C
5. E

Question 11

when do the deciduous teeth erupt,

when does calcification begin,

when is the enamel complete?

Answer 11

Question 12

in what order does the permanent maxillary teeth erupt?

Answer 12

1. 6
2. 1
3. 2
4. 4
5. 5
6. 3
7. 7

Question 13

in what order does the permanent mandibular teeth erupt?

Answer 13

1. 6
2. 1
3. 2
4. 3
5. 4
6. 5
7. 7

Question 14

when do the permanent teeth erupt,

when does calcification begin,

when is the enamel complete?

Answer 14

Question 15

when it root development complete in the primary dentition?

Answer 15

complete c12 months post eruption

Question 16

when it root development complete in the permanent dentition?

Answer 16

complete c3 years post eruption