Tooth Eruption Flashcards
What is the name of animals that have 2 sets of teeth?
Diphyodont
What does the term thecodont mean?
Tooth in socket in jaw
What does the term heterodont mean?
It means one animal has different types of teeth (e.g. incisors, canines etc)
When do teeth start forming in embryonic life?
Week 5
At what point do the teeth stop developing? Approximately what age is this?
Continues until the roots of the third permanent molars are completed (around 20 years of age)
What are 5 general differences between primary and permanent teeth?
Cues:
- S & W
- MD > CO
- B&L–> O
- Thinner
- Occlusal slope
- Smaller and whiter (primary teeth)
- Mesiodistal diameter is greater than cervico-occlusal dimension (of primary molar crown)
- Buccal and lingual surfaces converge towards the occlusal
- Enamel and dentin are thinner in primary teeth
- Cervical enamel rods slope occlusally.
Ends abruptly at cervixrather than being oriented gingivally and gradually becoming thinner as in permanent teeth
How do the contact points differ between primary and permanent teeth?
In primary teeth they are broaded and flatter
In permanent teeth the contact points are small, distinct and circular
Do permanent or primary teeth have shorter clinical crowns?
Primary
Of which teeth, primary or permanent, are the pulp chambers proportionately larger and closer to the surface?
Primary teeth
Why do the roots of deciduous molars diverge so greatly?
To allow for the developing permanent premolars
In which teeth, primary or permanent, is the crown short, relative to the length of the root?
Primary teeth
What is the definition of shedding?
Physiological process for elimination of deciduous teeth by resorption of their roots prior to eruption of their permanent successors.
What are the local factors that affect shedding?
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
What are the genetic factors that affect shedding?
- Apoptosis in PDL fibres
- Initiation of root resorption
Which tissues resorb when teeth shed?
Hard tissue and soft tissue
is the pattern of shedding asymmetrical or symmetrical?
Symmetrical (right to left symmetry)
Do the upper or lower teeth shed first?
Lower teeth shed first
In which arch does shedding follow anterior to posterior order?
Mandible
In which arch does the first molar shed before the canine?
Maxilla (upper)
In which teeth does resorption initiate at the lingual side of the root?
All anterior deciduous teeth
Where does resorption initiate in deciduous molars?
Initiates on the inner surface where the permanent premolars initially develop
Which two are the most common deciduous teeth that persist beyond their shedding time?
Upper B, Lower E
What are common reasons why deciduous teeth may be retained?
Usually due to congenital missing or impaction of permanent teeth or ankylosis (fuses into surrounding bone) due to trauma
Although retained deciduous teeth appear normal, why will resorption eventually occur?
Resorption occurs due to heavy masticatory forces
If a tooth is ‘submerged’ what does this mean?
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
Which deciduous teeth are mostly seen to be submerged?
Lower Es
What is a common cause of submerged deciduous teeth?
Ankylosed deciduous teeth often because of trauma
The permanent is either impacted or out of alignment
What are examples of abnormalities of shedding?
- Retained teeth
- Submerged teeth
- Remnants of deciduous teeth
What causes remnants of deciduous teeth?
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
Predeciduous/natal teeth are a rare condition where teeth are present in newborns. What issues can arise with this condition?
- May cause eruption cyst
- Danger of inhaling
- Cause of discomfort when breastfeeding
What is the definition of tooth eruption?
The process whereby a tooth moves from its developmental position within the jaws to emerge in the oral cavity
Name the 4 possible mechanisms for eruption
- Root formation: space for growing root accommodated by occlusal movement of tooth crown
- Hydrostatic pressure: within periapical tissues pushing the tooth occlusally
- Bone remodelling
- Pulling of the tooth in occlusal direction by the cells and fires of the periodontal ligament
What are 2 control of eruption mechanisms that have been suggested?
Hormonal control
Physical control
Name the 6 stages in tooth development
- Thickening stage
- Bud stage
- Early cap stage
- Late cap stage
- Bell stage
- Crown stage
