periodontium Flashcards
what are the 3 functions of the periodontium?
retain tooth in socket
resist masticatory loads
defensive barrier, protecting tissues against threats from the oral environment
why is the periodontium a unique situation?
it is the only breach in the body’s surface
junctional epithelium is physical barrier separating body tissues from oral environment
what are the periodontal tissues?
cementum
gingiva
alveolar bone
periodontal ligament
what does cementum cover?
root dentine
what components make cementum similar in structure to bone?
collagen matrix
lamellar arrangement
what does cementum provide attachment for?
some periodontal fibres
what are the 2 types of periodontal fibres?
cellular cementum
acellular cementum
what is cementum laid down by?
cementocytes
describe acellular cementum
no cells
adjacent to dentine
first formed (primary)
describe cellular cementum
cementocytes
apical part of root and furcation regions
later formed (secondary)
describe acellular extrinsic fibre cementum
collagen fibres from pdl
-attach and cross cementum
present on cervical 2/3 of root
responsible for tooth attachment
describe cellular, intrinsic fibre cementum
no sharpey’s fibres
intrinsic collagen fibres parallel to surface
no role in tooth attachment
what is the function of alveolar bone?
provides attachment for pdl fibres
supports the teeth
describe the anatomy of alveolar bone
similar to bone elsewhere in body
cortical plate forms inner lining of tooth socket
penetrated by nutrient canals
inner cancellous bone containing marrow
what happens to alveolar bone when teeth are lost?
alveolar process is resorbed, leaving a residual ridge
what kind of tissue is the pdl?
a connective tissue
what does the pdl contain?
cells extracellular matrix fibres nerves b.v
what cells are in the pdl?
fibroblasts cementoblasts osteoclasts cementoclasts eptithelial cells -debris of malassez defence cells
what are the components of the extracellular matrix
hyaluronate GAGs glycoproteins -fibronectin proteoglycans -proteodermatan sulphate -chondroitin/dermatan SO4 hybrid
what are the functions of sensory nerves in the pdl?
mechanoreceptors -rapid/slowly adaptin -proprioception-chewing control nociceptors -protective reflexes -inhibit jaw elevator motor neurons
what is the function of autonomic nerves?
b. v control
- vasoconstriction
what is the blood supply to pdl?
from inferior and superior alveolar arteries, passing into pdl from alveolar bone
what is the blood supply to gingivae?
from lingual and palatine arteries
what are the 2 periodontal fibres?
true pdl
-fibres connecting tooth to bone at or apical to alveolar crest
gingival ligament
-fibres mainly above alveolar crest
