Exam 2 - Cementum

Question 1

Which is the LEAST mineralized: bone, dentin, cementum, enamel?

Answer 1

cementum

Question 2

Cementum is __% organic, __% mineral.

Answer 2

50; 50

Question 3

What type of collagen is most prevalent in cementum?

Answer 3

Type I

Question 4

What components are made out of type I collagen in cementum?

Answer 4

intrinsic fibers

Sharpey’s fibers

Question 5

Cementum, unlike dental pulp, does not contain ___.

Answer 5

glycoproteins

Question 6

What are the functions of cementum?

Answer 6

attachment for PDL
continuous apical opposition when teeth wear
may repair minor root fractures

Question 7

Extra ____ is laid down from the bottom to put tooth back into occlusion, while ____ is formed from the top to reduce proximity to the pulp.

Answer 7

cementum; reparative dentin

Question 8

Cementum is formed from ____ cells.

Answer 8

neural crest (ectomesenchymal cells)

Question 9

T/F: Cementum is innervated.

Answer 9

FALSE - cementum is avascular and is not innervated

Question 10

T/F: Cementum contains Haversian and Volkmann’s canals.

Answer 10

FALSE - cementum does NOT contain these structures

Question 11

Where is cementum thinnest? Thickest?

Answer 11

thinnest at CEJ

thickest at the apex of the root

Question 12

Cervically, cementum is ____; apically, cementum is ____.

Answer 12

thinner and more acellular; thicker and more cellular

Question 13

T/F: At the apex of the root, cementum contains lacunae with cementocytes.

Answer 13

TRUE

Question 14

Is the cementum perforated?

Answer 14

YES to allow for Sharpey’s fiber attachments

Question 15

____ are the cells responsible for the secretion of the organic matrix of cementum.

Answer 15

Cementoblasts

Question 16

Where are cementoblasts derived from?

Answer 16

undifferentiated mesenchymal cells that originate in the proximal zone of the dental follicle

Question 17

Where do the undifferentiated mesenchymal cells that form cementoblasts originate in?

Answer 17

the proximal (inner) zone of the dental follicle

Question 18

All cells in the dental follicle are derived from ___.

Answer 18

ectomesenchyme (neural crest cells)

Question 19

Differentiation of the undifferentiated mesenchymal cells into cementoblasts are initiated by what?

Answer 19

the disruption of Hertwig’s epithelial root sheath

Question 20

Tiny perforations in Hertwig’s root sheath allow ____ to leak out of the pulp and make contact with undifferentiated mesenchymal cells and induce differentiation.

Answer 20

dentin matrix growth factors (BMP, FGF, DMP)

Question 21

What causes the differentiation of undifferentiated mesenchyme to cementoblasts?

Answer 21

perforations in Hertwig’s sheath that leak out dentin matrix growth factors that stimulate differentiation

Question 22

Depositional lines and reversal lines both indicate _____ and run longitudinally from crown to apex.

Answer 22

incremental growth

Question 23

_____ secrete cementum matrix which becomes mineralized.

Answer 23

Cementoblasts

Question 24

____ contain lacunae and canaliculi.

Answer 24

Cementocytes

Question 25

____ are the spaces occupied by cell bodies.

Answer 25

Lacnuae

Question 26

____ are the spaces occupied by cytoplasmic projections that allow cells to connect and coordinate reparative functions.

Answer 26

Canaliculi

Question 27

____ are the insertion of the PDL into acellular cementum to allow attachment of bone to cementum.

Answer 27

Sharpey's fibers

Question 28

In __% of patients cementum overlaps enamel.

Answer 28

60

Question 29

In __% of patients cementum joins enamel end-to-end.

Answer 29

30

Question 30

In __% of patients cementum stops short of enamel and leads to heightened sensitivity.

Answer 30

10

Question 31

What is the loss of tooth structure at the buccal or labial cervical areas called?

Answer 31

abfraction

Question 32

____ is caused by tensile and compressive forces during tooth flexure.

Answer 32

Abfraction

Question 33

Tensile and compressive forces during flexure cause ____ of cementum and underlying dentin.

Answer 33

resorption

Question 34

____ causes deep, narrow V-shaped notches/lesions.

Answer 34

abfraction

Question 35

Does abfraction usually affect single teeth?

Answer 35

YES

Question 36

What type of teeth does abfraction usually affect?

Answer 36

premolars and canines - teeth with excursive interferences or occlusal loads

Question 37

____ is the loss of dental tissue caused by foreign substances (e.g. toothbrush).

Answer 37

Abrasion

Question 38

Where is abrasion usually located?

Answer 38

cervical areas of teeth

Question 39

In ____ lesions are more wide than deep.

Answer 39

abrasion

Question 40

Abrasion commonly affects which teeth?

Answer 40

premolars, canines and molars

Question 41

What are calcified bodies appearing on or in the cementum and PDL in response to local trauma or hyperactive occlusion?

Answer 41

cementicles

Question 42

T/F: Cementicles have an increasing prevalence with increasing age.

Answer 42

TRUE

Question 43

How are cementicles classified?

Answer 43

free attached (inside cellular layer) embedded (covered by epithelial tissue)

Question 44

Cemental spurs are caused by ___ or ___.

Answer 44

traumatic occlusion; local response to trauma

Question 45

What cementum abnormality causes a hook that digs into the PDL, which can make extraction difficult?

Answer 45

cemental spurs

Question 46

What is the excessive production of cementum that generally involves the apical 1/3 of the root?

Answer 46

hypercementosis

Question 47

What cementum abnormality causes a bulbous root tip?

Answer 47

hypercementosis

Question 48

____ is possibly causes by occlusal trauma, periapical inflammation, and compensation for occlusal attrition.

Answer 48

Hypercementosis

Question 49

What prevents the reattachment of collagen onto cementum?

Answer 49

hypermineralization of exposed cementum

Question 50

The rough surface of exposed cementum facilitates ____ absorption.

Answer 50

endotoxin

Question 51

The rough surface of exposed cementum facilitates the attachment of ___ and ___.

Answer 51

plaque; calculus

Question 52

Enamel ___ bacterial biofilm formation; cementum ___ bacterial biofilm formation.

Answer 52

repels; allows

Question 53

What does scaling and root planing treatment cause?

Answer 53

smear layer to form

Question 54

What are the possible causes of resorption?

Answer 54

excessive orthodontic movement | trauma from occlusion

Question 55

T/F: Roots cannot repair themselves once the cause of resorption is removed.

Answer 55

FALSE - roots CAN repair themselves if the cause is removed

Question 56

Where are accessory canals found? What do they allow for?

Answer 56

found inside the root, allowing vascular tissues and GFs to reach apical mineralized tissues

Question 57

What stimulates cementoblasts to initiate repairs?

Answer 57

extra nutrients and growth factors

Question 58

Where are accessory canals found in multi-rooted teeth? What is the prevalence?

Answer 58

in the furcation area; 28%

Question 59

Where are accessory canals found in single-rooted teeth? What is the prevalence?

Answer 59

in the apical third; 17%