Perio 1

Question 1

periodontium

Answer 1

alveolar process, cementum, PDL

develops during a series of complex interactions of mesenchyme, HERS, and dental follicle

Question 2

gomphosis

Answer 2

fibrous peg-in-socket joint

Question 3

origins of periodontium

Answer 3

osteoblasts: surrounding mesenchyme tissues
cementoblasts: hers/ follicle cells- ectomesenchymal cells
PDL fibroblasts: follicle cells/ ectomesenchymal
odontoblasts: form dentin part of cemento-dental junction, dental papilla

Question 4

alveolar process: origin

Answer 4

formed by intramembranous ossification (mesenchyme to bone)
about 8th week of uterine life
crypts develop around tooth germs
develops substantially during eruption, under influence of follicle
remodled throughout life
anodontic individuals: alveolar process development impaired

Question 5

alveolar process structure

Answer 5

alveolar bone proper: compact bone

supporting alveolar bone both compact and trabecular (inside)

Question 6

alveolar bone proper

Answer 6

1- cribriform plate- has volkmanns canals running through it
2- lamina dura: area of PDL attachment
3- Bundle Bone: Sharpeys fibers embedded in bone is Inner (towards PDL): remodled quickly due to constant adaptation- pimary woven bone but lamellar bone is present
outer- lamellar bone continuous with supporting alveolar bone

Question 7

supporting alveolar bone

Answer 7

cortical plate (inner is lingual)
alveolar crest- junction of cortical plate and alveolar bone proper (thinner in maxilla)
central spongiosa- 1) Trabecular bone supporting alveolar bone and cortical plate 2) marrow (red hemopoetic then yellows as age)

Question 8

alveolar process

Answer 8

interradicular spetum-between roots

interalveolar septum- between teeth

Question 9

functions of alveolar bone

Answer 9

1- protection and structure for tooth to rest in
2- attach PDL
3- support of tooth roots
4- distribution of loading from the tooth and PDL to surrounding bone

Question 10

PDL origins

Answer 10

develops together with cementum and alveolar process
develops after detachment/fragmentation of HERS
starts off as unorganized fibrillar short connective tissue
ectomesenchyme cells differentiate into fibroblast which produce and organize collagen fibers
remodles throughout life
developing cells of the PDL may also prevent mineralization and ankylosis

Question 11

PDL

Answer 11

fibroblasts, mesenchymal cells, epithelial cells and macrophages
ranges from .15 to .38 in width (younger thicker)
collagen (1,3,12) supported by non-collagenous protein matrix
very dynamic environment

Question 12

oxytalan

Answer 12

main elastic fiber of PDL
assocaited with vasculature
run vertically from cementum to tooth apex
possibly regulate vascular response of PDL

Question 13

vasculature of PDL

Answer 13

very vascularized
superior/inferior alveolar arteries
arterioles penetrate the cribifrom plate- more in posterior and mandible
arterioles in interstitial areas
critical for tissue healing/regeneration

Question 14

PDL innervation

Answer 14

nerves arrive apically and through cribiform plate

run axially in tooth

Question 15

4 types of nerve endings

Answer 15

1- free nerce endings (most rpevalent, branched, more in apex) nocicpetive/ mechanoreceptive
2- ruffini corpuscles: bulbous dendritic endings. associated with schwann cells and collagen fibers- slow adapting mechanoreceptor
3- coiled nerve ending around midregion of the PDL: unknown function
4- spindle nerve ending- rare and unknown function

Question 16

PDL fiber orientation

Answer 16

alveolar crest group, horizontal group, oblique group, apical group, interradicular group

Question 17

gingival ligament

Answer 17

not part of PDL proper, collagen fibers which pass through oral lamina proper
attachemnt of gingival margin
1-dentogingival- cervical cementum to lamina propria
2-alveolargingival group-alveolar crest to laminar propria of gingiva
3-circular group- circular band around neck of tooth, attaches to fibers and free gingiva
4- dentoperiosteal group- run apically from cementum to periosteum of outer cortical plate
5-transpetal; runs from cementum just under junctional epithelium to adjacent tooth (ortho relapse)