bds2 periodontium Flashcards
function of the periodontium
- retain tooth in the socket
- resist masticatory forces
- defensive barrier to protect tissues against threats from the oral environment
what is junctional epithelium
physical barrier separating the body tissues from the oral environment
describe acellular cementum
extrinsic fibre cementum
collagen fibres from periodontal ligament
cervical 2/3 of roots
describe cellular cementum
intrinsic fibre cementum
intrinsic collagen fibres parallel to the surface
play no role in tooth attachment and this can represent a transitional form
what is the cortical plate of alveolar bone
this is the part of alveolar bone that forms the inner lining of the tooth socket
what are volkmanns canals
nutrient canals that penetrate the alveolar bone
what is a residual ridge
when teeth are lost the alveolar process is resorbed and this leaves the ridge
components of the periodontal ligament matrix include
hyaluronate glycosaminoglycans
glycoproteins eg fibronectin
proteoglycans eg proteodermatan sulphate, or chondroitin sulphate
what is the main property of the periodontal ligament matrix
behave as a viscoelastic gel
list the sensory nerves of the periodontal ligament
mechanoreceptors (a beta and a delta fibres)
- these are rapidly or slowly adapting
- responsible for proprioception and control of chewing
nociceptors (a delta and C fibres)
- protective reflexes to inhibit the jaw elevator motor neurons
explain the sympathetic aspect of periodontal ligament innervation
blood vessel control and vasoconstriction
explain the blood supply of the periodontal ligament
from the inferior and superior alveolar arteries, passing into the periodontal ligament from the alveolar bone
also comes from the lingual and palatine arteries to supply the gingivae
what is true periodontal ligament
fibres connecting tooth to bone at/apical to the alveolar crest
what is the gingival ligament
fibres mainly above the alveolar crest including free gingival fibres
what is the width of the periondontal ligament
0.2mm
function of oxytalan fibres in the periodontal ligament
present in the human periodontal ligament although the function is uncertain
are there elastic fibres in the periodontal ligament of humans
no
principle fibre groups in the alveolodental ligament
alveolar crest
horizontal
oblique
apical
interradicular ( only in multi rooted teeth )
what are the principle fibre groups in the interdental ligament
the transseptal fibres
describe the gingival fibre group
supports the free gingivae
what are the intrusive forces that the periodontal ligament is subjected to
mastication
swallowing
speech
parafunction
what are extrusive forces
sticky foods and orthodontic forces
which two elements are the anchors of the periodontium
the tooth and the alveolar bone
which tissue is the most complicated organised tissue in the body and why is that
the periodontal ligament because of the tissues associated with it
what are the black dots in a ground section
where the cells once were
which type of cementum is responsible for tooth attachment
acellulular
where is acellular cementum absent
furcation regions
what are the mechanoreceptors of the PDL associated with
fine tuning of the softness or hardness of the food being chewed
which PDL fibres are only found in the multi rooted teeth
inter radicular
which fibres cross the space and connect tooth to tooth
trans septal
which fibres run around the tooth
alveologingival fibres
what is the much gingival junction
the subdivision between attached gingiva and alveolar mucosa is called the mucogingival junction
what is the length of the muco gingival junction relevant for
treatment and evaluating the progression of periodontal disease
why should the lips be pulled back when taking an impression
to extend the alveolar mucosa to show a good picture of the muco gingival junction where the gingival is attached
what is the enamel cuticle
decalcified section where enamel is removed. coating of enamel when the tooth is prepared and there is some remainder
describe free gingiva
has a sulcus or crevice containing crevicular epithelium covering the sulcus. not attached to enamel to form the sulcus
junctional epithelium is attached to the tooth and is the most important tissue to highlight as it attaches the gingiva to the tooth and has a special attachment - the basal laminate has one internal and one external with hemidesmosomes to organise the attachment of the epithelium to the enamel
describe how oblique fibres attach
to the cementum, apically
to the bone, cervically
what are the main fibres in sharpeys fibres
collagen type I and III
where is acellular cementum located
2/3 cervical region of the root
where is cellular cementum
third apical region of the root and also found on furcation regions of multi rooted teeth
where is acellular extrinsic fibre cementum
2/3 cervical region of the root
where is cellular intrinsic fibre cementum located
third apical region of the root and furcation regions of multi rooted teeth
where is cementum thicker
apical region
describe the route of principle oblique fibres and the reason for this
wavy line form cementum to bone to provide further elastic resilience to the fibres as they transfer the energy from the tooth to the bone
which cells are found at the surface of cementum
cementocytes
what is the main cell type at the centre of the periodontal ligament
fibroblasts
where are sharpey fibres bundled more closely
cementum, spread at the bone to dissipate masticatory forces and protect the bone
what are the advantages of horizontal fibers
responsible for dealing with lateral forces that the tooth dissipates to the bone during masticatory excursions. powerful forces as you have to slide on tooth against the other as well as then cutting food
why is changing the root rotational arrangement important
when teeth need to be rotated, the root rotation must be changed as horizontal fibres will be stretched and bring the tooth back if there is no maintenance to allow the fibres to rearrange themselves
what is responsible for periodical cysts during tooth development
epithelial cell rests of malassez
group of principle fibres attaching cementum from one tooth to the adjacent tooth.
Transseptal fibre
Teeth cementum to gingiva
dento gingival fibres
Teeth to connective covering of the bone and periosteum
dento periosteal
Alveolar bone to gingiva
alveolo gingival
what is the dento gingival junction
Boundary between the oral cavity and the underlying connective tissue of the tooth supporting tissues.
why is oral gingival epithelium easiest to identify
due to keratin and functional role in mastication
