PDL Flashcards
PDL is a ____ CT structure
fibrous
*despite being fibrous in nature; it is also has many cells
is the PDL vasculaized and innervated?
YES!
-cementum is not
the thin PDL connects?
cementum layer to adjacent alveolar bone
where is the thinnest portion of PDL?
thinnest portion around middle third of root
*0.15-0.38mm
principle function of PDL?
- supporting teeth in their sockets while permitting them to withstand forces of mastication
- *sensory receptor for positioning of jaw (full of nociceptors)
- remodeling for resorbing function
- nutritive function due to being well-veascularized
principle fibers of the PDL form
strong fibrous union between teh root cementum and the bone
ankylosis
fusion of root to bone
*PDL fibroblasts may inhibit mineralization so this doesn’t occur
Name and describe the 5 PDL type 1 collagen fibrils bundles called?
1) alveolar crest group
- -below CE junction, down, out
2) horizontal group
- -right angle to root surface, apical
3) oblique group
- -oblique angle, coronally towards bone
4) periapical group
- -around apex, base of socket
5) interradicular group
- -in multirooted teeth at crest/furcation
PDL extracellular substances?
1) fcollagen fiberes
2) oxytalan fibers
3) glycosaminoglycans and glycoproteins (ground substance)
pressure-tension hypothesis
showing tooth displacement leading to compression and tension in the surrounding bone
alveolar bending hypothesis
tooth movement causing bending of the alveolar bone
stretched fibre hypothesis**
stretching and compression of PDL fibres leading to low and high strain areas in the surrounding bone
name and describe the 5 gingival ligament fibers’s fibers are imbedded
1) dento-gingival
- -most numerous, cervical cementum to free/attached gingiva
2) bone of the alveolar crest to free/attached gingiva
3) circular
- -around neck of teeth, free gingiva
4) apically over cementum over the outer cortical plate to alveolar process or vestibule of mouth
5) trans-septal
- -cementum between adjacent teeth, over the alveolar crest
bundle bone
where unraveled PDL fibers inter mesh with adjacent fibers and insert into the bone
*contain Sharpey’s fibers
define reversal line
location where the last cycle of bone resorption was followed by bone deposition
*the latter resulted from the production by osteoblasts of a thin seam of new bone in which very short Sharpey’s fibers are imbedded
TEM of periodontal ligament fibroblasts are responsible for?
1) synthesis of collagen and its assembly into collagen fibers
2) removal of collagen fibers during the continuous remodeling
digestive vacuoles majoridly remove?
collagen
*aka intracellular collagen in digestive vacuole
collagen fibrils are digested by _____ enzymes that have been added to the vacuoles
lysosomal enzymes
*the presence of these enzymes has been confrimed by cytochemical localization
are neural elements myelinated or not?
- myelinated near the apical end
* unmyetlined more coronally
most of the neural branches near the apical end are?
MIXED. consisting of myelinated and non-myelinated axons
the distribution of nerve bracnhes is closely associated with that of?
blood vessels
PDL is rich in blood supply originating primarily from? communicating with what vessels?
- *originating off dental arteries that enter through the apical foreman, LOTS of anastomoses
- ligament vessels also communicate with supraperiosteal vessels
the PDL contains an assortment of cells that are capable of generating and maintaining 3 distinct tissues. What are they?
1) ligament itself
2) mineralized tissues
3) alveolar bone
what are the major cell types of PDL?
1) osteoblasts
2) osteoclasts
3) fibroblasts =MOST ABUNDANT
4) epithelial cells= hertwigs
5) macrophages= defense
6) undifferenciated cells
7) cementoblasts
8) vascular elements
() neural elements
