Eruption and Shedding

Question 1

The movements a tooth makes to attain and maintain its position in the jaw is known as ___.

Answer 1

eruption

Question 2

What direction does a tooth not move during eruption?

Answer 2

apically

Question 3

T/F. Tooth movement occurs throughout life.

Answer 3

True.

Question 4

The movements of eruption are a ___ activity involving different cell types of the ___ ___.

Answer 4

cellular; periodontal ligament

Question 5

What cells are involved in movements of eruption?

Answer 5

cementoblast
osteoblast
osteoclast
fibroblast

Question 6

What is the most numerous cell type of the periodontal ligament?

Answer 6

fibroblast

Question 7

What are the 3 functions of fibroblasts?

Answer 7

1. secretes extracellular substance (fibroblast)
2. lysis extracellular substance (fibroclast)
3. may become a contracting cell (fibromyocyte)

Question 8

What is a contracting cell called?

Answer 8

a ‘fibromyocyte’ myofibroblast

Question 9

A fibromyocyte or myofibroblast is a cell that is connected to principal ___ fiber bundles that connect the tooth to ___ bone, when it contracts the collagen fibers ___ moving the tooth.

Answer 9

collagen; alveolar; contract

Question 10

What are the 3 stages of eruption?

Answer 10

1. preemergence
2. prefunctional
3. functional

Question 11

What is the main direction of movement during the preemergence stage?

Answer 11

facially

Question 12

What is the main direction of movement during the prefunctional stage?

Answer 12

occlusially

Question 13

What is the main direction of movement during the functional stage?

Answer 13

mesially

Question 14

The preemergence stage starts with the appearance of the ___ ___ and continue to the appearance of the ___ ___ ___ and ___ root sheath, just prior to the start of root ___ formation.

Answer 14

dental lamina; reduced enamel epithelium; Hertwig’s; dentin

Question 15

After enamel formation is complete, what do the four cell layers of the enamel organ form?

Answer 15

the reduced enamel epithelium

Question 16

The cervical loop is where the ___ and ___ layers of the enamel organ come together to form ___ ___ ___ ___.

Answer 16

outer; inner; Hertwig’s epithelial root sheath

Question 17

How is the reduced enamel epithelium attached to the completed enamel surface?

Answer 17

by a basal lamina

Question 18

During demineralization of a forming crown of an extracted tooth, the reduced enamel epithelium is attached to ___ enamel.

Answer 18

immature

Question 19

What are the two main functions of Hertwig’s epithelial root sheath?

Answer 19

1. determines the number of root canals of tooth

2. determines the root dentin outline

Question 20

T/F. The preemergence stage starts after root formation.

Answer 20

False, it starts BEFORE root formation

Question 21

In what stage are the number of root canals determined?

Answer 21

Preemergence

Question 22

The openings in the Hertwig’s ___ indicate the number of root ___ before the start of root formation.

Answer 22

diaphragm; canals

Question 23

The ___ stage starts with root dentin formation and ends when the tooth reaches occlusial plane.

Answer 23

prefunctional

Question 24

The apical end of Hertwig’s epithelial root sheath continues as the ___ and determines the number of root ___.

Answer 24

diaphragm; canals

Question 25

When the HERS breaks up, what process occurs cervically?

Answer 25

cemetogenesis

Question 26

The first step in the fate of HERS is the ___/___ stage. Here the number of root ___ is determined and the tooth erupts ___ from this level.

Answer 26

sheath/diaphragm; canals; occlusially

Question 27

During the second step of the fate of HERS, the ___ elongates to determine the root ___ outline. The ___ remains at relatively the same level.

Answer 27

sheath; dentin; diaphragm

Question 28

Finally, the root ___ forms when the sheath breaks-up in the last step of the fate of HERS. ___ forms on exposed dentin. This sequence continues ___ until root dentin is completed.

Answer 28

dentin; Cementum; apically

Question 29

T/F. Remnants of epithelial cells from HERS in the periodontal ligament appear during the functional stage of eruption. This is known as the epithelial rest of Malassez.

Answer 29

False. Remnants of epithelial cells from HERS in the periodontal ligament appear during the PREFUNCTIONAL stage of eruption. This is known as the epithelial rest of Malassez.

Question 30

During the prefunctional stage of eruption, what merges with the reduced enamel epithelium and undergoes cell death?

Answer 30

oral epithelium. The allows the coronal most part of the tooth to emerge into the oral cavity

Question 31

Once the tooth emerges into the oral cavity, what does the reduced enamel epithelium become?

Answer 31

the junctional epithelium

Question 32

What attaches the junctional epithelium to the tooth surface?

Answer 32

basal lamina

Question 33

The basal lamina can be found along the surfaces of the ___ and ___ and it continues to the ___ tissue (lamina propria) side of the free gingival junctional epithelium.

Answer 33

enamel; cementum; connective

Question 34

T/F. There are two basal lamina associated with the junctional epithelium.

Answer 34

True.

Question 35

Which eruption stage begins with the occlusal plane and physiologically continues throughout life?

Answer 35

functional stage

Question 36

What positions can you find junctional epithelium as it changes throughout life?

Answer 36

A. Attached to enamel B. Attached to enamel and cementum C. Attached to cementum

Question 37

What stage of eruption does the functional arrangement of principal fibers of PDL occur?

Answer 37

functional stage

Question 38

T/F. Attrition, dead tracts, and reparative (teritary) dentin can lead to changes during functional eruption.

Answer 38

True.

Question 39

Continued ___ formation, reduced ___ tissue volume and ___ mineralization are all examples of changes that can occur during the functional stage of eruption.

Answer 39

dentin; pulp; ectopic

Question 40

A bone ___ can be seen on radiograph surrounding the ___ molar during the preemergence stage.

Answer 40

crypt; third

Question 41

___ is defines as the physiologic elimination of ___ teeth by the resorptive action of ___.

Answer 41

Shedding; primary; odontoclasts

Question 42

Where do odontoclast originate from? How does it get to its target site?

Answer 42

bone marrow; via lood vessels

Question 43

T/F. Odontoclast resorb the 4 mineralized tissues of teeth.

Answer 43

three

Question 44

What must remain intact on the enamel of permanent premolars if they wish to avoid damage during shedding?

Answer 44

reduced enamel epithelium