PDL & cementum Flashcards
What does the PDL do in regards to the tooth?
thin sheet of fibrous CT located between the root of the tooth and its bony socket and connects to the tooth and the bony wall of the tooth sokcet
Cementoblast form ____
cementum
Osteoblasts form _____
bone
what are the epithelial rests of lamassez
remnants of hertwig’s epithelial root sheath.
what is the largest component of the PDL
fiber bundles
true/false: The PDL has a rich supply of nerves, lymph and blood vessels, blood cells, and endothelial cells.
true
where is the PDL thickest and thinnest?
thickest at the CEJ and apex and thinner in between
name 5 functions of the PDL
supportive, sensory, nutritional, formative, and resorptive
___ is the major function of the PDL and suspends the tooth in the socket
supportive
_____ nerve fibers transmit pressure and pain for the PDL
sensory
____ contains cementoblasts and osteoblasts in the PDL
formative
____ occurs in response to severe pressue
resorptive
5 principle fiber bundles of the PDL
- alveolar crest
- horizontal
- oblique
- apical
- interradicular
what fiber bundle group of the PDL resists horizontal movements, and extends from the cervical cementum and runs downward to the alveolar crest
alveolar crest group
what fiber bundle group of the PDL extends from the cementum to the bone at right angles and resists horizontal pressure against the crown of the tooth
horizontal group
what fiber bundle group of the PDL extends from the cementum to the bone in a diagonal direction. This group is the most numerous and resits vertical pressures that threaten to drive the root into the socket
oblique group
which fiber bundle group of the PDL extends from the apex of the tooth to the bone and secures the tooth in its socket and resists forces that might lift the tooth out of the socket
apical group
what fiber bundle group of the PDL is seen only in multirooted teeth and extends from the cementum in the furcation are of the tooth to the alveolar bone to help stabalize the tooth
interradicular group
what are sharpey’s fibers?
ends of the PDL fibers that are embedded at 90 degrees in the cementum and alveolar bone.
name 4 characteristics of cementum
color, location, resistance, doesn’t contain
light yellow in color
overlies and is attached to the dentin of the root
more resistant to resorption than bone which is why its possible to move teeth
does not have blood, nerve, or lymph supply because it gets its nutrients from the PDL
3 functions of cementum
- anchors the PDL to the tooth
- protects the dentin and seals in the dentin tubules
- cementum formation compensates for tooth wear
cementum is a calcified layer of ______ that covers the root of the tooth
connective tissue
What are two major components of cementum and their characteristics?
- organic matrix: densly packed collagen fibers help together by the gel-like extracellular ground substance
- mineralized: hydroxyapatite crystals that contains no blood vessels or nerves
2 types of cementum with their location, components found in it, thickness range
- acellular cementum: contains no cementocytes, first to form, covers the cervical third of tooth, cannot reproduce more once lost, 30-60 microns thick, and sharpeys fibers make up most of the acellular cementum
- cellular cementum: contains cementocytes, formed after tooth has erupted, less calcified, 150-200 microns thick, sharpeys fibers amount is small
what are the two parts to the alveolar bone
alveolar proper and alveolar supporting
alveolar bone surrounds ___ and provides attachment for ____
surrounds the rooth
attachment for the PDL
____ contains small holes for fibers and blood vessels
cribiform plate
____ is seen on radiographs as a white line continuour with the crestal bone
lamina dura
____ fiber bundles of PDL are inserted at 90 degrees
bundle bone
where is the supporting alveolar bone located
surrounds the alveolar bone proper and gives support to the socket
___ bone is found on the facial and lingual surfaces of the alveolar process and won’t show up on a radiograph
compact bone
____ bone lies between the alveolar proper and the cortical bone
cancellous bone
_____bone is located on the F & L surfaces of roots
redicular
___ bone is located between the roots of multi-rooted teeth
interradicular
T/F: The interproximal bone is not higher than facial and lingual bone
False
most common dehiscence (which teeth) & what is it
maxillary canines
cleft like absence of cortical plate
Bone liability
least stable, in constant change, formation is continuous
what is hyperfunction?
occlusal trauma; bone may thicken on F & L cortical plates, size & number of trabeculae increase
what is hypofunction?
tooth not in function or occlusion; bone resorbs, size & number of trabeculae decrease
Does bone have blood vessels and nerves?
yes
