tooth eruption

Question 1

What is tooth eruption

Answer 1

The process where a tooth moves from its developmental position within the jaw to its functional position within the oral cavity

Question 2

Name the 3 phases of tooth eruption

Answer 2

1. Pre eruptive
2. Eruptive- pre functional
3. Post eruptive- functional

Question 3

What is the pre eruptive phase

Answer 3

Refers to the movement of the developing tooth arising from growth of the tooth germ itself or form growth changes in the surrounding bone

Question 4

What does the pre functional/ eruptive phase of tooth eruption refer to

Answer 4

Refers to the active phase of movement of the tooth into its functional position following crown completion

Question 5

What does the functional/ post eruptive phase of tooth eruption refer to

Answer 5

Refers to the constants slow outward movement of the teeth to accommodate for the loss fo enamel due to occlusal wear

Question 6

State the formal tooth eruption is depend on

Answer 6

Net eruptive force= generated force - resistance

Question 7

What does the net eruptive force formula mean in words

Answer 7

If the force pushing or pulling the tooth out is greater than the resistance to the movement then the tooth will erupt

Question 8

What is a lack of eruption usually due to

Answer 8

Caused by either a reduced force or an increased resistance

Question 9

What happens to the tooth once it enters the oral cavity

Answer 9

Occlusal forces will start to impinge and will provide a large component of any resistance to eruption

Question 10

How is the overlying bone and gingiva covering teeth with no predecessor removed

Answer 10

1. The reduced enamel epithelium which covers the enamel proliferates into the overlying gingival connective tissue and released enzymes which start to degrade the connective tissue matrix
2. It also releases cytokines
3. it prevents the simultaneous action of osteoclasts on the enamel which of course is subjected to the same pressure

Question 11

What di the cytokines released by the reduced enamel epithelium do

Answer 11

1. Trigger the adjacent fibroblast to also release degrading enzymes
2. Strats the cascade of events which lead to the recruitment of osteoclast and subsequent bone removal

Question 12

What happens as the cusps of the tooth approach the gingival epithelium

Answer 12

1. Remaining connective tissues becomes ischemic and necrotic
2. Where the reduced enamel epithelial meets the oral epithium they fuse and continued pressure results in degradation of the fused epithelium above the cusp

Question 13

What happens as the remaining connective tissue becomes ischemic and necrotic

Answer 13

It triggers an inflammatory reaction redness, sourness and raised temperature

Question 14

What form the initial junctional epithelium

Answer 14

Derived from the remnants of the reduced enamel epithelium

Question 15

List the 5 criterias that must be fulfilled to be able to explain what generated the eruptive force for tooth eruption

Answer 15

1. The proposed system must be capable of producing a force under physiological conditions which is sufficient to move a tooth in the required direction
2. Experimentally induced changes in the system should cause predictable changes in eruption
3. The system myst have characteristics which allow it ti sustain eruptive movements over long periods
4. The biochemical and physiological characteristics of the system should be consistent with the production of an eruptive force
5. The morphological features associated with the system should be consistence with the production of the eruptive force

Question 16

Evidence suggests that the eruptive forces for teeth resides where?

Answer 16

Resides around the tooth in the periodontal space

Question 17

How might periodontal fibroblast migration aid in the eruption of teeth

Answer 17

When the periodontal fibroblasts migrate through the periodontal matrix they either:
1. Pull out the tooth
2. Act in a contractile fashion contracting the matrix and pulling the tooth out

Question 18

What happens to a permanent tooth when its corresponding deciduous tooth erupts

Answer 18

The permanent tooth develops further a wall of bon which divides the socket into 2
Eventually the permanent tooth is completely enclosed in its bony crypt

Question 19

As the unerputed permeant tooth continues to grow and erupt what happens

Answer 19

Pressure is applied to the wall of bone and as a result osteoclasts are recruited and the bone begins to resorb

Question 20

What is the area where bone respiration of erupting teeth called

Answer 20

Resorbing organs of Tomes

Question 21

What happens as the tooth continues to grow and erupt

Answer 21

Eventually complete loss of the intervening bone palate occurs and resorption of the root cementum and dentine of the deciduous tooth

Question 22

What are the cells that degrade the tooth called

Answer 22

Odontoblasts or dentinoclasts

Question 23

What are odontoblasts/ dentinoclasts identical to

Answer 23

Osteoclasts

Question 24

Describe how a deciduous tooth falls out

Answer 24

eventually the permanent tooth comes into a position directly under the deciduous tooth
the deciduous tooth has very little root and supporting periodontal ligament
occlusal forces increases a child grows and eventually a critical point is reached when the tissue ruptures and the tooth falls out

Question 25

Which teeth exfoliate and erupt in a slightly different way to the rest

Answer 25

Pre molars

Question 26

Where do premolars develop

Answer 26

the pre molars develop between the splayed roots of the deciduous molar

Question 27

What can sometimes happen during premolar eruption and why

Answer 27

Because of the splayed nature of the roots of deciduous molars sometimes resorption process will miss the most apical root fragment causing that to stay in the tissue even after the tooth has been lost