PDL, alveolar bone, cementum, vascular/lymphatic supply

Question 1

PDL

Answer 1

PDL =

• -connective tissue structure that surrounds the root and connects it to bone
• -continuous with CT of gingiva
• -communicates with marrow spaces through vascular channels in the bone

Question 2

principle PDL fiber bundles (6)

Answer 2

1. alveolar crest
2. horizontal
3. oblique**MAJORITY
4. apical
5. interradicular
   * *6. transseptal: do not go from bone to tooth, so he says to keep in gingiva

Question 3

alveolar crest PDL fibers

Answer 3

• from cervical cementum to crestal bone just below junctional epithelium
• counterbalance force of more apical fibers, keeping tooth in socket

Question 4

horizontal PDL fibers

Answer 4

• extend horizontally from cementum to alveolar bone, perpindicular to tooth root (long axis of tooth)
• counterbalance force of more apical and coronal fibers, stabilizing tooth in socket

Question 5

oblique PDL fibers

Answer 5

• largest group
• extend from cementum coronally to bone
• take vertical/occlusal forces and transform them to tension forces on bone

Question 6

apical PDL fibers

Answer 6

• radiate from cementum to bone at fundus of socket (at the root apex)
• not found in teeth with incompletely formed roots

Question 7

interradicular PDL fibers

Answer 7

• go through furcation

- extend across crest of interradicular bony septum of multirooted teeth

Question 8

transseptal PDL fibers

Answer 8

• extend interproximally are are embedded in cementum of adjacent teeth
• *??? bc he said keep them classified in gingival fibers

Question 9

sharpey’s fibers

Answer 9

terminal parts of PDL fibers where they insert into bone or cementum

Question 10

cell types in PDL

Answer 10

• fibroblasts
• cementoblasts
• osteoblasts (form bone)
• osteoclasts (destroy bone)
• macrophages
• epithelial rest cells: in devo, they got left behind in PDL adn do nothing

Question 11

alveolar bone

Answer 11

• alveolar processes = part of maxilla/mandible that provides housing for roots of teeth
• comprised of alveolar bone proper (adjacent to tooth), cancellous bone, compact bone

Question 12

normal level of alveolar bone

Answer 12

• usually 2mm cementum exposed between CEJ adn crest of alveolus
• in that cementum space, crestal fibers and gingival CT attach
• coronal to that is CEJ adn junctional epithelium

Question 13

compact bone

Answer 13

• superficial/outer surface of buccal adn lingual plates
• densest
• you want implants to contact this becasue denser

Question 14

cancellous bone

Answer 14

• supporting bone

- comprised of bony trabeculae with irregularly shaped marrow spaces

Question 15

alveolar bone proper

Answer 15

AKA cribiform plate

• *solid narrow zone of compact bone around tooth
• radiographically seen as lamina dura
• comprised of dense compact bone adn bundle bone (bone with sharpey’s fiber insertions)

Question 16

bundle bone

Answer 16

part of alveolvar bone proper (in addition to compact bone) that is where sharpey’s fibers insert

Question 17

radiograph of alveolar bone

Answer 17

• dark line next to tooth is PDL

- white bone just beyond that is alveolar proper, which is called LAMINA DURA

Question 18

interdental bone contour depends on…

Answer 18

• contour of enamel and interdental width aka shape of contact (bone follows shape of gingiva)
• degree of eruption
• position and angulation of tooth (crest of bone parallels CEJ of adjacent teeth - optical illusion in supraerupted/ tipped teeth)
• BL width/position of tooth

Question 19

facial adn lingual bone depends on…

Answer 19

• alignment and position of teeth (normal, crowded, spaced)
• angulation of root (tipped facially = thinner facial plate)
• occlusal forces may result in thicker bone (bruxer/grinder)
• posterior bone thicker than anterior

Question 20

fenestration

Answer 20

isolated area where the root is denuded of bone, leaving only the periosteum adn gingiva over the root with marginal bone intact
**just a little hole (window) where root peeks out through bone, can only find in surgery, not by probing bc of jxnal epithelium

Question 21

dehiscence

Answer 21

• denuded area of bone that goes all the wya through marginal bone
• if loss of CT attachment, you could potentially probe down this
• usually on facial, so you cannot see on film bc of dense tooth

Question 22

occurence of fensetration adn dehiscences

Answer 22

20% of teeth
faical more common that lingual
anterior more common than posterior

Question 23

alveolar bone composition

Answer 23

70% inorganic, 30% organic (mainly type I collagen)

**least stable periodontal tissue under constant turnover

Question 24

cells of alveolar bone

Answer 24

• osteoblasts: produce organic matrix of bone
• osteoclasts: bone resorption
• osteocytes: resident cells of bone

Question 25

cementum

Answer 25

- primary = acellular, does not continue to grow, more cervical (near CEJ), sharpeys fibers - secondary = cellular, contains cementocytes in lacunae, formed after tooth reaches occlusal plane, apical portion (other fibers in addition to sharpeys fibers embedded in it), thicker - cementum covers roots

Question 26

cementum - near CEJ, near apex

Answer 26

primary is near CEJ | secondary is more apical

Question 27

cementum thicknes

Answer 27

- primary (cervical 2/3): 16-60 micrometers | - secondary (apical 1/3 adn furcations): 150-200

Question 28

CEJ overlap %s

Answer 28

overlap = 60% edge to edge = 30% fail to meet = 10% (**hypersensitivity bc of exposed dentin)

Question 29

sharpeys fibers angle

Answer 29

insert at 90 degrees into cementum, parallel to cemental fibril

Question 30

vascular supply of periodontium

Answer 30

numerous anastomoses

Question 31

vascular supply maxilla

Answer 31

**superior alveolar artery --> dental a, intraseptal a which then penetrate bone to supply alveolar process, PDL, gingiva **anterior adn posterior superior alveolar aa + infraorbital a + greater palatine a --> supraperiosteal branches, which become teh PDL vessels **PDL vessels supply alveolar process, PDL, gingiva

Question 32

vascular supply to mandible

Answer 32

**inferior alveolar a --> dental a + intraseptal a, which penetrate the bone and supply the alveolar process, PDL, gingiva **buccal, facial, mental, sublingual aa --> supraperiosteal branches which become the PDL vessels **PDL vessels supply the alveolar process, pDL and gingiva

Question 33

PDL vessels

Answer 33

- from supraperiosteal branches - supply PDL, alveolar bone, gingiva * maxilla: anterior + posterior superior alveolar aa --> supraperiosteal branches * mandible: buccal, facial, sublingual, mental aa --> supraperiosteal branches

Question 34

dental and intraseptal arteries

Answer 34

-penetrate bone adn supply PDL, alveolar process, gingiva * *maxilla: from superior alveolar a * *mandible: from interferior alveolar a

Question 35

venous vessels

Answer 35

- return of venous blood and lymph parallels arterial supply - deep cervical nodes: palatal gingiva and tissue around 3rd molars - submental nodes: mandibular incisor tissues - submandibular: everything else

Question 36

innervation

Answer 36

TRIGEMINAL NERVE * gingiva: posterior/middle/anterior superior alveolar, infraorbital, greater palatine, nasopalatine, mental, buccal, and lingual * PDL: posterior/middle/ anterior superior alveolar, palatal, infraorbital, inferior alveolar