periodontium Flashcards
what is the periodontium?
tissues surrounding and supporting the the teeth
name the 3 periodontal tissues?
cementum
PDL
alveolar bone
give 3 functions of the periodontium
. retain tooth in socket
. defence barrier
. resist masticatory load
which structure separates body tissues from the oral environment?
junctional epithelium
what structure covers root dentine?
cementum
compare the structure of cementum to bone
. centrum has a linear lamellar arrangement whereas bone has a radial, cementum is avascular
. both have collagen matrix
name the 2 types of cementum?
acellular and cellular
compare cellular and acellular cementum
acellular:
. no cells, adjacent too dentine, 1st formed
cellular
. contains cementocytes, formed later, present in apical part of tooth and furcation regions
which type of cementum is 1st formed?
acellular
what are the hstolgogical classifications of cementum?
acellular extrinsic fibre cementum and cellular intrinsic fibre cementum
which cementum contains sharpers fibres?
acellular extrinsic fibre cementum
which cementum has no role in attachment?
cellular intrinsic fibre cementum
alveolar bone is penetrated by nutrient cannals called?
volkmans canals
what structure provides attachment for pdl/sharpeys fibres?
alveolar bone - lamina dura
what are 2 functions of PDL?
attach tooth to jaw
transmit biting force to alveolar bone
what does PDL contain?
cells
ecm
nerves
BVs
which cells does PDL contain?
fibroblasts epithelial osteoblats cementoblasts defence cells
what does ecm in PDL contains?
hyaluronate GAGs
glycoproteins
proteoglycans
which 2 types of sensory nerves does the PDL contains?
mechanoreceptors (a beta and a delta)
nociceptors (a delta and c)
where does blood supply to PDL originate?
inferior and superior alveolar arteries
palatine and lingual arteries
whites the function of true PDL fibres?
connect tooth to bone at apical or alveolar crest
what type of fibres are the principal fibres in true PDL
collagen type 1 and 2
name the 5 PDL principal fibres in the alveoli-dental ligament
alveolar crest horizontal oblique apical interradicular (multirooted)
name the PDL interdental ligament fibre
transeptal fibres
what do PDL transeptal fibres connect?
tooth to tooth
what do gingival fibres do?
hold gingiva firmly against tooth
which type of fibres are gingival fibres?
collagen
desmosomes and hemidesosomes are involved in connecting junctional epithelium to tooth, compare the function of both
desmosomes - attach adjacent cells
hemidesmosomes - attach cells to epithelium (adhesion)
what is the connection point between 2 teeth called?
col
what is the advantage of the orientation of oblique fibres?
biting forces transmitted and dissapated to bone
where is acellular centrum found?
all parts of root
where is centrum thickest?
apex
which structures pass through gaps in inner cortical plate of alveolar bone?
BVs passing through nutrient canals
are collagen fibres straight or wavy and why?
wavy - allow small amount tooth movement
what is the main cell type in PDL?
fibroblast
fibroblast funciton
form and degrade collagen and form ground substance of PDL
which side of PDL are fibre bundles larger?
bone side
which side of pdl are fibres closer together?
cementum side
which fibre group are seen in interdental region and not labial or lingual aspects of periodontium?
transeptal
which fibres seen on lingual and labial aspects of periodontium endnote interdental regions?
alveolar crest
fibres not attached to bone?
transeptl, gingival
type of epithelium in gingiva?
strat squamous
oral epithelium vs sulcular
sulcular thinner and not keratinised
