Tooth Eruption & Shedding

Question 1

Permanent anterior teeth begin developing ___ to incisal level of pri teeth early in pre-eruptive stage.

Answer 1

lingual

Question 2

Mixed dentition phase

Answer 2

8-12 years old

Question 3

Permanent premolars move from near occlusal area of pri molars to ___ roots of pri molar.

Answer 3

within

Question 4

Maxillary molars form within maxillary A w/ occlusal surfaces inclined B.

Answer 4

A: tuberosities
B: distally

Question 5

Occlusal surfaces of mandibular molars slope ___ as they develop in mandibular rami.

Answer 5

mesially

Question 6

When does pre-functional eruptive phase begin & end?

Answer 6

It begins w/ development of root & ends when teeth makes occlusal contact.

Question 7

Name the 4 impt events which occur during pre-functional eruptive phase

Answer 7

1. Development of root
2. Proliferation & fusion of reduced enamel epithelium & oral epithelium
3. Emergence of crown tip from fused epithelial layers
4. Incisal/Occlusal contact

Question 8

What protects new enamel?

Answer 8

Primary cuticle

Question 9

When does formation of Guber-na-cular canal occur?

Answer 9

Pre-function eruptive phase

Question 10

Characteristic of Gubernacular canal

Answer 10

• Triangular
• No blood vessels & nerves (have been degenerated)
• Margin has follicular fibers called gubernacular cord/gubernaculum dentis

Question 11

How are blood vessels & nerves in Gubernacular region degraded?

Answer 11

Macrophages

Question 12

In which direction do PBLs form?

Answer 12

Cervical to apical

Question 13

What transient structure forms beneath tooth during pre-functional eruptive phase?

Answer 13

Bone ladder

Question 14

Order of shedding of pri teeth

Answer 14

Cent incisors, lateral incisors, mand canines, 1st molars, max canines & 2nd molars

Question 15

Age cent incisors shed

Answer 15

6-7 years old

Question 16

Age lateral incisors shed

Answer 16

7-8 years old

Question 17

Age mand canines shed

Answer 17

9-12 years old

Question 18

Age max canines shed

Answer 18

10-12 years old

Question 19

Age 1st molars shed

Answer 19

9-11 years old

Question 20

Age 2nd molars shed

Answer 20

10-12 years old

Question 21

What initiates resorption of root?

Answer 21

Pressure exerted by erupting permanent tooth

Question 22

Where does resorption of root begin on pri anterior teeth?

Answer 22

Lingual surface

Question 23

Where does resorption of root begin on pri molars?

Answer 23

Inner surfaces of teeth

Question 24

Type of enzyme in vacuoles of odontoclasts

Answer 24

Acid phosphatase

Question 25

Molecule which inhibits differentiation of odontoclast

Answer 25

OPG

Question 26

Molecule which promotes differentiation of odontoclast

Answer 26

RANKL

Question 27

Resorbed enamel & dentinal surfaces are coated w/ ___.

Answer 27

cementum

Question 28

What type of cementum is deposited in larger & deeper resorption bays?

Answer 28

Cellular

Question 29

Where are odontoclasts commonly found?

Answer 29

Root surface

Question 30

Single-rooted teeth often shed ___ resorption of root is done.

Answer 30

before

Question 31

For pri molars, roots completely resorb & crown partially resorbs ___ shedding.

Answer 31

before

Question 32

After root resorbs, dentogingival junction migrate A holding tooth B before shedding.

Answer 32

A: apically
B: cervically

Question 33

Initiations for shedding

Answer 33

Pressures from…

1. erupting tooth
2. masticatory force
3. tumor

Question 34

How does pressure from erupting tooth cause shedding?

Answer 34

1. Pressure causes resorption of root
2. Less surface area for attachment of PDL
3. Weakens tooth support

Question 35

How does pressure from mastication cause shedding?

Answer 35

1. Muscle increases in size w/ age
2. Heavy force exerted on tooth
3. PDL can’t withstand
4. Trauma
5. Resorption

Question 36

Periodontal ligament resorbed thru ___.

Answer 36

apoptosis