Tooth Eruption and Exfoliation

Question 1

what is the Gubernacular Canal?

Answer 1

the canal which connects the dental lamina of unerupted tooth to the lamina propria of the gingivae at the site of eruption

Question 1

what happens to the deciduous tooth as the permanent tooth begins its pressure to erupt?

Answer 1

the deciduous root cementum and dentine begins to resorb

osteoclasts are also recruited

Question 2

with the incisors, from which angle do the permanent teeth sit from to the deciduous?

Answer 2

lingually

Question 3

where does the permanent pre-molar sit prior to eruption?

Answer 3

between the splayed roots of the deciduous molar

• allows the deciduous roots to resorb in multiple areas

Question 4

define tooth eruption

Answer 4

when tooth moves from developmental position within the jaw into position within the oral cavity

Question 5

what are the 3 phases of tooth eruption? describe each.

Answer 5

1. pre-eruptive (pre-eruptive)
   - refers to movement of tooth from tooth germ itself and its growth changes within the bone
2. pre-functional (eruptive)
   - active phase of tooth into crown completion
3. functional (post-eruption)
   - constant outward flow of tooth, accommodating for loss of enamel due to wear

Question 6

what is the net eruptive force?

Answer 6

the generated force pushing the tooth out minus the resistance pushing the tooth back in

Question 7

what may be the sources of resistance for teeth?

Answer 7

occlusal forces

Question 8

what 2 things happen as the tooth begins to erupt through the surface?

Answer 8

1. remaining epithelial connective tissue becomes ischaemic and necrotic
   - triggers inflammatory response
   - red, swelling, soreness (teething)
2. reduced enamel epithelium fuses to oral epithelium, force degrades the fusion, forms a canal from which tooth can erupt

Question 9

what is the reduced enamel epithelium?

Answer 9

sits on top of regular enamel and protects enamel during eruption

• after eruption, remnants of reduced enamel epithelium becomes the junctional epithelium

Question 10

what are the 5 criteria of eruptive force?

Answer 10

1. the system must be capable of producing a force to move a tooth in the right direction
2. experimental changes should cause predictable changes in eruption
3. system must be able to sustain eruptive movements over long periods
4. the biochemical and phsiological characteristics of a system should be consistent with the production of the force
5. the morphology of the system should be consistent with the production of the force

Question 11

what are the 2 categories which are the suggested generators of eruptive force? expand on these.

Answer 11

periodontal
- fibroblast migration/contraction
- vascular pressure

extra-periodontal
- root growth
- pulpal cell proliferation
- fundic bone deposition - as new bone layed down, tooth needs to be pushed out