PDL, alveolar bone, cementum, vascular/lymphatic supply Flashcards
PDL
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
principle PDL fiber bundles (6)
- alveolar crest
- horizontal
- oblique**MAJORITY
- apical
- interradicular
* *6. transseptal: do not go from bone to tooth, so he says to keep in gingiva
alveolar crest PDL fibers
- from cervical cementum to crestal bone just below junctional epithelium
- counterbalance force of more apical fibers, keeping tooth in socket
horizontal PDL fibers
- 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
oblique PDL fibers
- largest group
- extend from cementum coronally to bone
- take vertical/occlusal forces and transform them to tension forces on bone
apical PDL fibers
- radiate from cementum to bone at fundus of socket (at the root apex)
- not found in teeth with incompletely formed roots
interradicular PDL fibers
- go through furcation
- extend across crest of interradicular bony septum of multirooted teeth
transseptal PDL fibers
- extend interproximally are are embedded in cementum of adjacent teeth
- *??? bc he said keep them classified in gingival fibers
sharpey’s fibers
terminal parts of PDL fibers where they insert into bone or cementum
cell types in PDL
- fibroblasts
- cementoblasts
- osteoblasts (form bone)
- osteoclasts (destroy bone)
- macrophages
- epithelial rest cells: in devo, they got left behind in PDL adn do nothing
alveolar bone
- 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
normal level of alveolar bone
- 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
compact bone
- superficial/outer surface of buccal adn lingual plates
- densest
- you want implants to contact this becasue denser
cancellous bone
- supporting bone
- comprised of bony trabeculae with irregularly shaped marrow spaces
alveolar bone proper
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)
bundle bone
part of alveolvar bone proper (in addition to compact bone) that is where sharpey’s fibers insert
radiograph of alveolar bone
- dark line next to tooth is PDL
- white bone just beyond that is alveolar proper, which is called LAMINA DURA
interdental bone contour depends on…
- 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
facial adn lingual bone depends on…
- 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
fenestration
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
dehiscence
- 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
occurence of fensetration adn dehiscences
20% of teeth
faical more common that lingual
anterior more common than posterior
alveolar bone composition
70% inorganic, 30% organic (mainly type I collagen)
**least stable periodontal tissue under constant turnover
cells of alveolar bone
- osteoblasts: produce organic matrix of bone
- osteoclasts: bone resorption
- osteocytes: resident cells of bone
cementum
- 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
cementum - near CEJ, near apex
primary is near CEJ
secondary is more apical
cementum thicknes
- primary (cervical 2/3): 16-60 micrometers
- secondary (apical 1/3 adn furcations): 150-200
CEJ overlap %s
overlap = 60%
edge to edge = 30%
fail to meet = 10% (**hypersensitivity bc of exposed dentin)
sharpeys fibers angle
insert at 90 degrees into cementum, parallel to cemental fibril
vascular supply of periodontium
numerous anastomoses
vascular supply maxilla
**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
vascular supply to mandible
**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
PDL vessels
- from supraperiosteal branches
- supply PDL, alveolar bone, gingiva
- maxilla: anterior + posterior superior alveolar aa –> supraperiosteal branches
- mandible: buccal, facial, sublingual, mental aa –> supraperiosteal branches
dental and intraseptal arteries
-penetrate bone adn supply PDL, alveolar process, gingiva
- *maxilla: from superior alveolar a
- *mandible: from interferior alveolar a
venous vessels
- 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
innervation
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
