Periodontium Flashcards
What is the periodontium?
the periodontium is the tissues surrounding and supporting the teeth
What does the periodontal tissues consist of
Cementum
Gingiva
Alveolar bone
Periodontal ligament
What are the functions of the periodontium
Retaining the tooth in its socket
Resisting masticatory loads and transferring them to the bone
As a defensive barrier protecting tissues against threats from the oral environment
What is the junctional epithelium
The physical barrier separating the body tissues from the oral environment
Why is the epithelial attachment in the oral environment unique
It is the only breach in the body’s surface
What is cementum
Cementum is a bone like layer of mineralized tissue which is deposited incrementally on the surface of the root
How is cementum similar to bone
Both have a collagen matrix
Both have a lamellar arrangement
How is cementum different to bone
Cementum has a parallel lamellar arrangement whereas bone has a radial lamellar arrangement
What does cementum cover
root dentine
What does cementum provide attachment for
some periodontal fibres
What is cementum laid down by
cementoblasts
Describe cellular cementum
Contains cementocytes
Later formed
Present in the apical part of the root and furcation regions
Covers acellular cementum
Describe acellular cementum
No cells within it
Usually adjacent to dentine
First formed
Fibres of the PDL terminate here (sharpey’s fibres)
Why is the presence of cellular/acellular cementum clinically relevant?
the responses to treatment will be different and so success rates of treatment is linked to the presence of acellular and cellular cementum
what are the alternative classifications of cementum based on the histological differences
acellular extrinsic fibre cementum
cellular intrinsic fibre cementum
describe acellular extrinsic fibre cementum
has collagen fibres from the PDL - sharpey’s fibres
present on cervical 2/3 of the root
why is acellular extrinsic fibre cementum more successful when it comes to regeneration
it has the ability to produce anchorage which is relevant to the treatment of periodontitis
describe cellular, intrinsic fibre cementum
no sharpey’s fibres
intrinsic collagen fibres parallel to surface
has no role in tooth attachment
may represent a transitional form
what makes alveolar bone different to normal bone
it is dependent for its development and persistence upon the presence of tooth
what does the cortical plate form?
the inner lining of tooth socket
what does the cancellous bone contain
marrow
blood vessels, nerves, lymph etc
what are volksman canals
they are small openings which supply the periodontal ligament with nutrients
what does the periodontal ligament contain
cells extracellular matrix fibres nerves blood vessels
what makes the extracellular matrix special
behaves as a viscoelastic gel - gives it capacity to return to its original shape
what is the extracellular matrix made up of
hyaluronate GAGs
glycoproteins
proteoglycans
what are the glycoproteins in the PDL matrix
fibronectin
what are the proteoglycans in the PDL matrix
proteodermatan sulphate
chondroitin/dermatin SO4 hybrid
what are the cells in the PDL
fibroblasts cementoblasts osteoclasts cementoclasts epithelial cells defence cells