Lecture 2 Flashcards
what is the origin of junctional epithelium during tooth eruption?
reduced dental epithelium
what is the origin of junctional epithelium after tooth eruption?
the cells of oral epithelium possess the ability to differentiate into cells of junctional epithelium
what is the structure of junctional epithelium?
widest in coronal portion (15-20 cell layers), thin towards the CEJ (3-4 cells)
does the junctional epithelium turnover?
yes- turnover rate faster than oral epithelium
does the junctional epithelium or oral epithelium have bigger size of cells?
junctional epithelium
does the junctional epithelium or oral epithelium have bigger size of intercellular space?
junctional epithelium
does the junctional epithelium or oral epithelium have bigger number of desmosomes?
oral epithelium
does the junctional epithelium or oral epithelium have potential to keratinize?
junctinal epithelium
how does junctional epithelium contact the tooth?
junctional epithelium is physically attached to the tooth, not simply in contact with it
when does periodontitis occur?
when junctional epithelium migrates apically down root surface
what is necessary for pocket formation?
viable junctional epithelium
what happens in necrotizing ulcerative periodontitis?
junctional epithelial cells die, so no pocketing
bone exposed
what is cal?
pocket depth+gingival recession
what cells are present in gingival connective tissue (lamina propria)?
fibroblasts- synthesizes matrix and fibers mast cells- vasoactive substances macrophages- phagocytosis and synthesis neutrophillic granulocytes lymphocytes plasma cells
what fibers are present in the gingival connective tissue?
collagen, reticulin, oxytalan, elastic
what do collagen fibers do?
characteristic cross banding
produced by fibroblasts, cementoblasts, and osteoblasts
what fibers are most abundant in gingival connective tissue?
collagen fibers
where are the reticulin fibers?
numerous adjacent to basement membrane
around blood vessels
where are the oxytalan fibers?
mostly in pdl
run parallel to long axis of tooth
where are the elastic fibers?
around blood vessel
what are the functions of the gingival fibers?
reinforce the gingiva
provide resilience and tone
maintain architectural form and integrity
where are the circular fibers?
encircle tooth like a cuff
where are the dentogingival fibers?
fan out from supra-crestal cementum into free gingiva
where are the dentoperiosteal fibers?
run from supracrestal cementum into attached gingiva
where are the transseptal fibers?
run from tooth to tooth (embedded in cementum)
what is the structure of periodontal ligament?
richly vascular and cellular connective tissue surrounding the roots and joining cementum and alveolar bone
what is the radiographic view of pdl?
the space between lamina dura (alveolar bone proper) and root surface
hourglass shape space
0.25 mm width
what are the functions of pdl?
permits forces to be distributed
essential for tooth mobility
what are the principal fibers of pdl?
alveolar crest fibers
horizontal fibers
oblique fibers
apical fibers
what are the cells of pdl?
fibroblasts, osteoblasts, cementoblasts, osteoclasts, epithelial cells, nerve fibers, epithelial cell rests of mallassez
where are the fibroblasts?
aligned along principal fibers
where are the osteoblasts?
line bone surface
where are the cementoblasts?
line cemental surface
where are the osteoclasts?
multinucleated, create ruffled surface of bone
what is cementum?
mineralized tissue covering tooth surface and occasionally small portions of the crown of the teeth
how is cementum different from bone tissue?
no blood vessels
no lymph vessels
no innervation
no physiologic resorption/remodeling
what are the other characteristics of cementum?
continuing deposition throughout life
collagen fibers embedded in organic matrix
high mineral content (65%), mainly HA
what are the intrinsic cemental fibers?
produced by cementoblasts
composed of fibers oriented parallel to root
what are the extrinsic fibers?
sharpey’s fibers
produced by pdl fibroblast
what are the different forms of cemental fibers?
acellular, extrinsic fiber cementum- coronal or middle portion of the root
cellular, mixed stratified cementum- apical third of the root and in the furcations
cellular, intrinsic fiber cementum- in resorption lacunae
what happens to cemental thickness throughout life?
increases by gradual apposition
what is the cementum thickness in cervical portion of the root?
20-50um
what is the cementum thickness in apical portion of the root?
150-250 um
what does the alveolar bone consist of?
bone formed by both dental follicle and cells independent of tooth development
what are the parts of alveolar bone?
cancellous bone, cortical bone, bone marrow
what does the bone marrow consist of?
adipocytes, vascular structures, undifferentiated mesenchymal cells
does the alveolar bone remodel?
remodels in response to forces and tooth movement
how is the alveolar bone made?
osteoblasts produce bone matrix (osteoid) consisting of collagen fibers, glycoproteins, and proteoglycans
osteoid undergoes mineralization by the deposition of minerals (calcium and phosphate)
what is the blood supply to gingiva?
supraperiosteal vessels- terminal branches of sublingual buccal mental facial greater palatine infraorbital posterior superior dental
what is the blood supplot to periodontal tissues?
dental artery
superior/inferior alveolar
intra-septa
rami perforantes (terminal branches of intra-septal, penetrate alveolar bone all through the socket)
lymphatic system
submental lymph nodes
deep cervival lymph nodes
submandibular lymph nodes
jugulodigastric lymph node
what are the nerves of the periodontium?
end branches of trigeminal nerve: infraorbital sublingual posterior superior dental mental greater palatal buccal long sphenopalatine
