Tooth Eruption and Exfoliation

Question 1

How do the primary and permanent dentitions develop in relation to one another?

Answer 1

at the same time

Question 2

How many teeth can the jaw of an infant fit?

Answer 2

20 teeth

Question 3

How many teeth can the jaw of a 4-5 year old accomadate?

Answer 3

20 erupted teeth and 28 developing teeth

Question 4

When is the mixed dentition stage?

Answer 4

8-12 years

Question 5

What is involved with the mixed dentition stage?

Answer 5

simultanous exfoliation of decidious teeth and eruption of permanent teet

Question 6

What is tooth eruption ?

Answer 6

the movement of a tooth from its site of development within the alveolar process to its functional position in the oral cavity

Question 7

What are the three stage of tooth eruption?

Answer 7

-pre-eruptive stage
-pre-functional eruptive phase
-functional phase (post-eruptive phase)

Question 8

What causes the movement of teeth in the pre-eruptive stage?

Answer 8

-growth of jaws
-growth of tooth buds
-remodeling of the walls in the bony crypt
(mesial migration results when there is resorption of the mesial wall with the concomitnant apposition of bone on the distal wall

Question 9

In which directions does the jaw increase in size?

Answer 9

-length of jaw (antero-posterior)
-width of jaw (coronal plane)
-alveolar ridge height
-buccal-lingual width of alveolus

Question 10

Which grows faster, teeth or the jaw?

Answer 10

teeth
-individual tooth germ grows rapidly and due to the jaw length ,they become crowded

Question 11

As the jaw increases in size, which way do the teeth move?

Answer 11

outward (facially) and toward the oral cavity (either upward or downward)

Question 12

Which way do the permanent molars grow in?

Answer 12

angled inclination prior to and during eruption and achieve vertical alignment only when the jaw length is sufficient to allow it

Question 13

What are the five theories of tooth eruption?

Answer 13

-root growth
-vascular pressure
-selective bone deposition and resorption
-pulpal pressure
-periodontal and gingival fiber ligaments

Question 14

What is the root growth theory of tooth eruption?

Answer 14

elongation of the roots in relation to stability of the fundus of the pocket

Question 15

What is the vascular pressure theory of tooth eruption?

Answer 15

increased hydrostatic pressures in the apical dental sac or periodontal ligament

Question 16

What is the selective bone deposition and resorption theory of tooth eruption?

Answer 16

coronal bone resorption concomitant with bone apposition in the fundus area

Question 17

What is the pulpal pressure theory of tooth eruption?

Answer 17

-tissue pressure differential in the pulp compared to the PDL
-decrease in pressure inside, PDL exerts pressure on the tooth and it moves up

Question 18

What is the periodontal and gingival fiber ligament theory of eruption?

Answer 18

cells (myofibroblasts) exert traction on the tooth through the collagen network and cell to cell contacts
-contacts help to push the tooth up

Question 19

What are the most frequently accepted theories of tooth eruption?

Answer 19

root growth, alveolar bone remodeling, and periodontal ligament formation

Question 20

What other factors influence tooth eruption?

Answer 20

-parathyroid hormone (influence mineralization and resorption of roots)
-MMPs produced by fibroblasts, osteoclasts, macrophages

Question 21

What is a gubernacular canal?

Answer 21

strand of connective tissue that contains remnants of dental lamina epithelium (derived from previous lamina)

Question 22

What is the best description of rate of eruption?

Answer 22

“burst of eruption” that averages about 3 mm every 3 months

Question 23

What is occlusal surface wear?

Answer 23

oblique fibers of PDL continue to pull tooth into occlusion as enamel is abraded

Question 24

What is a compensatory eruptive mechanism to continued occlusal abrasion?

Answer 24

apical cementum deposition

Question 25

What is proximal wear (mesial drift)

Answer 25

mesial inclination of teeth in full contact will yield an anterior force vector and when coupled with the pull of the transseptal fivers

Question 26

What are odontoclast?

Answer 26

cell derived from monocytes that exit capillaries to become connective tissue macrophages
-these form a multinucleated giant cell that function like osteoclast

Question 27

What do odontoclasts do?

Answer 27

degrade both collagenous and non-collagenous matrix of cementum and dentin and the hydroxyapatite mineral phase

Question 28

What is a fibroclast?

Answer 28

specialized fibroblasts like cells that are thought to destroy the collagen fibers of the PDL associated with resorbing tooth root

Question 29

What tooth typically gets messed up during eruption>

Answer 29

canine, bc its gotta fit in that little tiny space