Tooth Eruption & Shedding Flashcards
Permanent anterior teeth begin developing ___ to incisal level of pri teeth early in pre-eruptive stage.
lingual
Mixed dentition phase
8-12 years old
Permanent premolars move from near occlusal area of pri molars to ___ roots of pri molar.
within
Maxillary molars form within maxillary A w/ occlusal surfaces inclined B.
A: tuberosities
B: distally
Occlusal surfaces of mandibular molars slope ___ as they develop in mandibular rami.
mesially
When does pre-functional eruptive phase begin & end?
It begins w/ development of root & ends when teeth makes occlusal contact.
Name the 4 impt events which occur during pre-functional eruptive phase
- Development of root
- Proliferation & fusion of reduced enamel epithelium & oral epithelium
- Emergence of crown tip from fused epithelial layers
- Incisal/Occlusal contact
What protects new enamel?
Primary cuticle
When does formation of Guber-na-cular canal occur?
Pre-function eruptive phase
Characteristic of Gubernacular canal
- Triangular
- No blood vessels & nerves (have been degenerated)
- Margin has follicular fibers called gubernacular cord/gubernaculum dentis
How are blood vessels & nerves in Gubernacular region degraded?
Macrophages
In which direction do PBLs form?
Cervical to apical
What transient structure forms beneath tooth during pre-functional eruptive phase?
Bone ladder
Order of shedding of pri teeth
Cent incisors, lateral incisors, mand canines, 1st molars, max canines & 2nd molars
Age cent incisors shed
6-7 years old
Age lateral incisors shed
7-8 years old
Age mand canines shed
9-12 years old
Age max canines shed
10-12 years old
Age 1st molars shed
9-11 years old
Age 2nd molars shed
10-12 years old
What initiates resorption of root?
Pressure exerted by erupting permanent tooth
Where does resorption of root begin on pri anterior teeth?
Lingual surface
Where does resorption of root begin on pri molars?
Inner surfaces of teeth
Type of enzyme in vacuoles of odontoclasts
Acid phosphatase
Molecule which inhibits differentiation of odontoclast
OPG
Molecule which promotes differentiation of odontoclast
RANKL
Resorbed enamel & dentinal surfaces are coated w/ ___.
cementum
What type of cementum is deposited in larger & deeper resorption bays?
Cellular
Where are odontoclasts commonly found?
Root surface
Single-rooted teeth often shed ___ resorption of root is done.
before
For pri molars, roots completely resorb & crown partially resorbs ___ shedding.
before
After root resorbs, dentogingival junction migrate A holding tooth B before shedding.
A: apically
B: cervically
Initiations for shedding
Pressures from…
- erupting tooth
- masticatory force
- tumor
How does pressure from erupting tooth cause shedding?
- Pressure causes resorption of root
- Less surface area for attachment of PDL
- Weakens tooth support
How does pressure from mastication cause shedding?
- Muscle increases in size w/ age
- Heavy force exerted on tooth
- PDL can’t withstand
- Trauma
- Resorption
Periodontal ligament resorbed thru ___.
apoptosis
