Tooth Eruption

Question 1

What is the name of animals that have 2 sets of teeth?

Answer 1

Diphyodont

Question 2

What does the term thecodont mean?

Answer 2

Tooth in socket in jaw

Question 3

What does the term heterodont mean?

Answer 3

It means one animal has different types of teeth (e.g. incisors, canines etc)

Question 4

When do teeth start forming in embryonic life?

Answer 4

Week 5

Question 5

At what point do the teeth stop developing? Approximately what age is this?

Answer 5

Continues until the roots of the third permanent molars are completed (around 20 years of age)

Question 6

What are 5 general differences between primary and permanent teeth?

Cues:

1. S & W
2. MD > CO
3. B&L–> O
4. Thinner
5. Occlusal slope

Answer 6

1. Smaller and whiter (primary teeth)
2. Mesiodistal diameter is greater than cervico-occlusal dimension (of primary molar crown)
3. Buccal and lingual surfaces converge towards the occlusal
4. Enamel and dentin are thinner in primary teeth
5. Cervical enamel rods slope occlusally.
   Ends abruptly at cervixrather than being oriented gingivally and gradually becoming thinner as in permanent teeth

Question 7

How do the contact points differ between primary and permanent teeth?

Answer 7

In primary teeth they are broaded and flatter

In permanent teeth the contact points are small, distinct and circular

Question 8

Do permanent or primary teeth have shorter clinical crowns?

Answer 8

Primary

Question 9

Of which teeth, primary or permanent, are the pulp chambers proportionately larger and closer to the surface?

Answer 9

Primary teeth

Question 10

Why do the roots of deciduous molars diverge so greatly?

Answer 10

To allow for the developing permanent premolars

Question 11

In which teeth, primary or permanent, is the crown short, relative to the length of the root?

Answer 11

Primary teeth

Question 12

What is the definition of shedding?

Answer 12

Physiological process for elimination of deciduous teeth by resorption of their roots prior to eruption of their permanent successors.

Question 13

What are the local factors that affect shedding?

Answer 13

Pressure from permanent successional tooth.

Increased force on deciduous teeth due to:

• Growth of face and jaws
• Enlargement of masticatory muscles

Summary: pressure + growth + loss of supporting tissue = exfoliation

Question 14

What are the genetic factors that affect shedding?

Answer 14

• Apoptosis in PDL fibres

- Initiation of root resorption

Question 15

Which tissues resorb when teeth shed?

Answer 15

Hard tissue and soft tissue

Question 16

is the pattern of shedding asymmetrical or symmetrical?

Answer 16

Symmetrical (right to left symmetry)

Question 17

Do the upper or lower teeth shed first?

Answer 17

Lower teeth shed first

Question 18

In which arch does shedding follow anterior to posterior order?

Answer 18

Mandible

Question 19

In which arch does the first molar shed before the canine?

Answer 19

Maxilla (upper)

Question 20

In which teeth does resorption initiate at the lingual side of the root?

Answer 20

All anterior deciduous teeth

Question 21

Where does resorption initiate in deciduous molars?

Answer 21

Initiates on the inner surface where the permanent premolars initially develop

Question 22

Which two are the most common deciduous teeth that persist beyond their shedding time?

Answer 22

Upper B, Lower E

Question 23

What are common reasons why deciduous teeth may be retained?

Answer 23

Usually due to congenital missing or impaction of permanent teeth or ankylosis (fuses into surrounding bone) due to trauma

Question 24

Although retained deciduous teeth appear normal, why will resorption eventually occur?

Answer 24

Resorption occurs due to heavy masticatory forces

Question 25

If a tooth is ‘submerged’ what does this mean?

Answer 25

The affected teeth do not come to the level of adjacent normal occluding teeth.

Submerged teeth are always 0.5 mm or more below the intact marginal ridges of the adjacent teeth

Question 26

Which deciduous teeth are mostly seen to be submerged?

Answer 26

Lower Es

Question 27

What is a common cause of submerged deciduous teeth?

Answer 27

Ankylosed deciduous teeth often because of trauma

The permanent is either impacted or out of alignment

Question 28

What are examples of abnormalities of shedding?

Answer 28

• Retained teeth
• Submerged teeth
• Remnants of deciduous teeth

Question 29

What causes remnants of deciduous teeth?

Answer 29

Usually due to more diverged roots of the deciduous teeth, especially molars, which can interferes with eruption path of permanent teeth.

And alongside smaller premolar size can cause this abnormality

Question 30

Predeciduous/natal teeth are a rare condition where teeth are present in newborns. What issues can arise with this condition?

Answer 30

• May cause eruption cyst
• Danger of inhaling
• Cause of discomfort when breastfeeding

Question 31

What is the definition of tooth eruption?

Answer 31

The process whereby a tooth moves from its developmental position within the jaws to emerge in the oral cavity

Question 32

Name the 4 possible mechanisms for eruption

Answer 32

1. Root formation: space for growing root accommodated by occlusal movement of tooth crown
2. Hydrostatic pressure: within periapical tissues pushing the tooth occlusally
3. Bone remodelling
4. Pulling of the tooth in occlusal direction by the cells and fires of the periodontal ligament

Question 33

What are 2 control of eruption mechanisms that have been suggested?

Answer 33

Hormonal control

Physical control

Question 34

Name the 6 stages in tooth development

Answer 34

1. Thickening stage
2. Bud stage
3. Early cap stage
4. Late cap stage
5. Bell stage
6. Crown stage