The Periodontium Anatomy Flashcards
what is the periodontium comprised of?
gingiva
PDL
alveolar bone
cementum
what is the function of the periodontium?
attachment of teeth to jaws
effective support during mastication
what are the 2 parts the gingiva is divided into?
- Attached
- Free
what is free gingiva?
Coronal to the epithelial attachment
what is the attached gingiva?
tightly bound to the underlying bone = muco-periosteum
function of the gingiva?
attachment between mucous membranes and teeth
prevents bacterial invasion of the underlying periodontal tissues
in health where are the gingiva attached to the teeth?
coronal to the ACJ
what are the gingiva comprised of?
fibrous CT covered by epithelium
extends from mucogingival junction to the tooth surface
what is the basic structure of the oral epithelium?
Stratified squamous epithelium
Keratinocytes (90%) and Non Keratinocytes
4 types of clear/non keratinocytes found in the oral epithelium?
Langherhans cells - defense
Melanocytes - pigment melanin
Lymphocytes
Merkel cells - sensory touch receptors
4 hisotlogical layers in keratinised epithelium?
1 - basal cell layer
2- prickle cell layer
3- granular layer
4- keratinized layer
where does cell division occur in the keratinized areas?
cell division occurs in the basal layer
cells move through the epithelium and shed
as this happens cells increase in size/flatten and keratin is produced
what is differentiation?
process packing cells together in the keratinized layer
example of non keratinized epithelium?
alveolar mucosa
lacks granular and keratinized layers = intermediate and surface
what is an MCG and when are they produced?
mucous coating granules - formed in prickle and granular layers
contains lipids released into intercellular spaces in keratinised/non k = forms barrier to water
3 areas of gingival epithelium?
- oral gingival epithelium - faces oral cavity - free/attached
- oral sulcular ep - faces tooth but not attached
junctional ep - attached to tooth
oral gingival epithelium structure?
stratified squamous ep
orthokeratinized - cells flat + no nuclei
what is the junction like between the oral gingival epithelium and the underlying connective tissue?
wavy course of connective tissue papillae and rete pegs of the epithelium project into each other
describe the sulcular epithelium?
lines sulcus faces tooth non keratinized shallow rete peg pattern not directly involved in attachment
what does the junctional epithelium allow? and how does it do this?
forms epithelial attachment to tooth
by hemi desomosomes anchoring basal keratinocytes to the basement membrane
how is the JE formed?
by fusion of the reduced enamel epithelium with the oral epithelium on eruption
moves down tooth as tooth erupts, stabilises near the ACJ
where does the JE terminate and what is its cell arrangement like?
terminates coronally in the base of the gingival crevice
JE cells orientate themselves parallel to the tooth
Rapid turnover of cells
how does cell division occur in the JE?
division occurs throughout, cells shed into sulcus
is the JE permeable?
poorly differentiated and do not synthesize MCG’s
also has large intercellular spaces so is readily permeable
what are the 2 main components of gingival connective tissue?
Collagen fibres/Extracellular matrix - produced by fibriblasts
highly vascular
cell types in gingival CT?
fibroblasts
macrophages
polymorphs/neutrophils
lymphocytes/plasma cells
how is collagen arranged?
circular fibres trans septal fibres dento gingival dento periosteal crestal
where do crestsal fibres stem from?
alveolar bone into attached gingiva
most common type of collagen in CT?
type 1
what is the extracellular matrix in gingival CT?
network of polysachharides and proteins secreted by cells
what is the periodontal ligament?
specialized vascular connective tissue
continuous with gingiva and pulp
derived from dental follicle
what is the pdl width?
ranges from 0.15-0.38
thinnest in middle third
decreases with age
role of the principal fibres in the pdl?
attachment of cementum to bone
groups of principal fibres?
oblique apical horizontal alveolar crest inter radicular
cells found in loose connective tissue?
fibroblasts
undifferentiated mesenchymal cells
defence cells
the extracellular matrix binds with water which is important for?
hydrostatic cushion
withstand mastication
blood vessels of pdl?
apical vessels
perforating/lamina dura
gingival vessels
what are cementoblasts?
line surface cementum and lay down cementum
what are osteoblasts?
line endosteal and periosteal alveolar surfaces, lay down bone
what are cementoclasts?
line surface cementum and break it down
what are osteoclasts?
line endosteal and periosteal surfaces - breakdown
what are oxytalin fibres?
unique to pdl elastic insert into cementum run parallel/oblique maintain potency of blood vessels during masticaiton
what are the cell rests of Malassez?
remnants of epithelial root sheath of hertwig
forms plexus around tooth - prevents ankylosis
what is bundle bone?
part of bone where tooth attaches
cribiform plate - heavily perforated with vessles/nerves
radiopaque lamina dura
types of cementum?
cellular
acellular
epithelial turnover affected by what hormones?
oestrogen
adrenaline
corticosteroids
what do TIMP’s do?
inhibit tissue damage by collagensases
