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Oral Histo > Periodontium > Flashcards

Flashcards in Periodontium Deck (80):
1

components of the periodontium

cementum, PDL, bony socket, gingiva (sulcular and junctional)

2

attachment to tooth includes all of the periodontium except for

sulcular epithelium

3

describe the initiation of periodontal development

root dentinogenesis, HERS separates from the developing root, cells migrate from the follicle into their locations to differentiate (fibroblasts, cementoblasts, and osteoblasts)

4

what secretes its organic matrix first

cementoblasts and osteoblasts...primarily composed of type I collagen

5

cementoblast and osteoblast matrix formation is proceded by

PDL fibroblasts secreting their organic matrix

6

describe PDL development

as the PDL fibers are secreted they intermingle in the unmineralized matrices and then become trapped during mineralization. Fibers are added apically and change their orientation over time (oblique, horizontal, oblique)...ending with fibers embedded in the cementum are more coronal than those in the alveolar bone. Now they are more stable and can thicken after eruption.

7

the development of the root and periodontium occurs

from the CEJ to the root APEX

8

what is another name for the initial cementum matrix

fiber fringe...dense group of collagen fibers oriented at right angles to the DCJ..it extends into the unmineralized dentin matrix. longer as you go coronally bc they are more mature.

9

describe the formation of the root dentin

predentin extends b/w the future DCJ and the pulp at the advancing root edge. more coronally, root dentin starts to mineralize and separates 2 regions of dentin: on the outside, unmineralized dentin and on the pulp side, predentin. even more coronally, the fringe fibers are enclosed completely by mineralized dentin

10

primary cementum

first formed, acellular, coronal 2/3 of root. important in serving an attachment fn. more mineralized

11

secondary cementum

formed after at least half the root is formed...when emerging into the oral cavity, cellular, apical 2/3 of the root. overlies the primary cementum. deposited more rapidly. cementoblasts become trapped in the matrix and are now called cementocytes. less mineralized. more important in adaptation...thickens the most in response to occlusal forces

12

cementinogenesis

fiber fringe layed down first and embedded in unmineralized dentin. dentin mineralizes more coronally, then discrete foci of 1' cementum start to mineralize. the mineralized foci start to coalesce= initial layer of cementum or acellular extrinsic fiber cementum.

13

why is 1' cementum acellular

cementoblasts don't get trapped in the ecm they are making, they retreat toward the future PDL

14

sulcular epithelium arises from

the embryonic oral epithelium

15

junctional epithelium arises from

the REE

16

the c.t components of the periodontium (PDL, bony sockey, and cementum) arise from

the precursor cells of the dental follicle

17

cellular origin of cementoblasts

1. ectomesenchyme (NCC)
2. epithelial/ectoderm/HERS
3. both

18

support for dental follicle origin

follicle cells were able to be prompted to differentiate into a mineralized tissue that resembled cementum

19

support for origin of HERS

observed cell types in HERS are an intermediate b/w an epithelial and mesenchymal phenotype...HERS could potentially be transformed into cementoblasts

20

evidence for both

both cell types (from epithelium and ectomesenchymal) found in close proximity to where cementum was being secreted.

21

bone morphogenetic proteins (BMP)

secreted growth factors, TGF superfamily, serves as an inducing signal that triggers cementoblast differentiation

22

runX

downstream from BMP, t.f, regulate the upregulation of the proteins that characterize differentiated cementoblasts

23

bone sialoprotein and osteopontin

secreted from cementoblasts at the same time the initial collagen matrix...may have something to do with cementum mineralization

24

Bone sialoprotein

has a particular AA sequence (arg, gly, asp) that binds to cell membranes and has a string of gluatmates that binds to HAP. might have something to do with CB adhesion to root dentin and triggering it's mineralization

25

3 fns of cementum

attachment of tooth to jaw, protection of root dentin, adaptation to forces

26

composition of cementum

45-50% organic (type I, 90 and type III collagen,1 , non-c proteins, ground substance)
50-55% inorganic (HAP)

27

is cementum vascularized

no

28

does cementum remodel

no

29

is cementum secreted throughout life

yes...but not normally resorbed...3X increase b/w ages 16-70

30

width of cementum

thinnest at CEJ, thickest at apex...so CEJ more vulnerable

31

acellular extrinsic fiber cementum

organic matrix of cementum is secreted by the cells and they don't get trapped in the cementum. composed of many sharpeys fibers. fibers oriented at right angles to the cementum surface

32

sharpeys fibers

mineralized ends of PDL fibers w/in the cementum

33

canines and incisors often are composed only of

acellular extrinsic fiber cementum (AEFC)

34

cellular intrinsic fiber cementum

secondary cementum. collagen fibers oriented parallel to the surface of the cementum with no connection of the PDL. cementoblasts that secreted the matrix become trapped=cementocytes

35

mixed fiber cementum

bulk of secondary cementum. 2 types of fibers, some intrinsic and some extrinsic. secreted after and more slowly than the initial wave of secondary cementum.

36

where is mixed fiber cementum more prominent

apically and interradicular region of multi-rooted teeth

37

tome's granular layer

hypomineralized regions of mantle dentin in the root

38

cementocytes

trapped cementoblasts. no longer involved in synthesizing cementum

39

changes in cementum deposition can be caused by:

1. environmental factors
2. attrition in the crowns (more)
3. periodontal disease with inflammation (more)

40

continued deposition of cementum can cause

the size of the apical foramen to become smaller

41

cementoid

cementum directly adj to the cementoblasts (in the PDL) that is unmineralized. usually associated with cellular cementum

42

what causes growth lines in cementum

idiocyncratic variations in the degree of calcification as cementum is deposited over time

43

hypercementosis

very large amounts of cementum are deposited around the root. can cause difficulties during procedures. irritation of gingiva, gingival recession. radio-opacities around roots.

44

PDL defined

soft c.t. large, highly organized bundles of collagen fibers that have ends embedded in cementum and bone. very thin. gets thinner w/ age

45

fns of the PDL

attachment, ligament

46

cells in the PDL

fibroblasts, cementoblasts, osteoblasts and osteoclasts, epithelial rests of mallasez, immune cells, mesenchymal cells

47

fibroblasts

secrete and degrade collagen, larger in the PDL (more active). most prominent in the central part of the ligament

48

cell-cell contacts of fibroblasts in the PDL

desmosomes and gap jns (synchronize collagen secretion).

49

jns with ECM to fibroblasts in the PDL

fibronexus...ecm fibronectin involved

50

importance of the jns b/w the PDL fibroblasts and the collagen of the ecm

occlusal forces that impinge on the ecm and the interior of the cell...react to forces by increasing/decreasing the production of collagen, modify the orientation of the fibroblast processes to orient the collagen fiber bundles of the PDL so that they align with the axis of strain in the ecm

51

all jns from the fibroblasts to the ecm attach to the

actin cytoskeleton in the fibroblast and interact with the collagen of the ecm (single transmembrane of complex)

52

when the PDL is inflamed

epithelial rest cells of mallasez can proliferate and form cysts

53

undifferentiated mesenchymal cells of the PDL

lie close to b.v, give rise to new fibroblasts,cementoblasts, and osteoblasts. maintan the viability of the periodontium

54

ecm of the PDL is composed of

collagen I and III (80:20), immature elastic fibers (oxytalin fibers) at right angles to the collagen, ground substance (PGs and GAGs and glycoproteins)

55

glycoprotein of the ecm of the PDL

fibronectin

56

cementicle

spherical calcified mass in the PDL

57

princible fiber groups of the PDL

organized collagen fiber bundles that act to attach the cementum to the adj alveolar bond

58

name the different fiber bundles of the PDL

1. alveolar crest
2. horizontal group
3. oblique
4. apical
5. interradicular

59

alveolar crest fibers

cementum to top of alveolar bone

60

horizontal group

cementum to alveolar bone below the top

61

oblique fibers

most numerous, cementum to bond in oblique direction (more apical on cementum)

62

apical fibers

apex of tooth to bone socket

63

interradicular fibers

in multi-rooted teeth...b/w cementum and interradicular septum of bond

64

gingival ligament

nearby group of collagen fibers including the transeptal ligament which connects the cementum of tooth into that on the adj tooth

65

main vascular supply to the PDL is from the

inferior alveolar artery and the superior alveolar artery (and gingival arteries)

66

routes to the PDL

foramina in bone...perforating arteries travel through. or accessory b.v branching off near the apical foramina

67

which arteries are less affected by endodontic procedures

perforating arteries

68

PDL innervation fibers

large Ab, Adelta, C fibers

69

what sensation is percieved in the PDL

proprioceptive and pain

70

what carries proprioception

Abeta...levels and direction of force

71

pain signals carried by

Adelta and C fibers

72

large Abeta fibers

perceive proprioception, highly sensitive, code for the AMOUNT AND DIRECTION of force, regulate chewing and localize stimuli

73

each nerve fiber of the PDL responds optimally to...

a different direction of force....allows us to sense different directions

74

dividing line b/w the alveolar process and the body of the maxilla and mandible is

just apical to the roots of the teeth

75

basal bone is what

bone just apical to the alveolar process

76

the alveolar process includes

1. outer cortical plate
2. central spongy region
3. bone lining the socket

77

bundle bone

contains PDL fibers

78

cribiform plate

foramina

79

lamina dura

thin and strong

80

bone lining the socket develops from the

dental follicle