Periodontal tissue Flashcards
What are the functions of the periodontium? (the tissues surrounding and supporting the teeth) (3 points)
- Retain tooth in socket
- Resist masticatory loads
- Defensive barrier, protecting tissues against threats from the orl environment
What is junctional epithelium?
- The physical barrier separating the body tissues from the oral environment
What are the 2 classifications periodontal diseases can be broadly divided into?
- Diseases of the gingiva alone
- Diseases of all periodontal tissues
What are false pockets?
- Gingival swelling
What are true pockets?
Loss of attachment of the periodontium
Which type of cementum is formed first? (primary cementum)
- Acellular cementum
Where is acellular cementum usually found?
- Adjacent to dentine
What type of cell lays down cementum?
Cementocytes (can use term cementoblasts but cementocytes preferred - cementocytes are inside the cell whereas cementoblasts are outside the cell)
What are the 2 types of cementum?
- Cellular cementum
- Acellular cementum
What does cementum provide attachment for?
- Some periodontal fibres
Does cellular, intrinsic fibre cementum play a role in tooth attachment?
No
Which type of cementum is equivalent to secondary cellular cementum?
Cellular, intrinsic fibre cementum
Does cellular, intrinsic fibre cementum contain Sharpey’s fibres?
No
What type of fibre does acellular extrinsic fibre cementum contain?
Collagen fibres from PDL (Sharpey’s fibres)
Where is acellular extrinsic fibre cementum found?
Present on cervical 2/3 of roots
What alternative classification of cementum is equivalent to acellular cementum?
Acellular extrinsic fibre cementum
Where is cellular cementum located?
- Present in the apical part of the root and in furcation regions
Which type of cementum is later formed? (secondary cementum)
- Cellular cementum
Which type of cell is found in cellular cementum?
- Cementocytes
In what way is cementum very similar in structure to bone? (2 points)
- Collagen matrix
- Lamellar arrangement
What does cementum cover?
Root Dentine
Which part of the alveolar bone forms the inner lining of the tooth socket?
- The ‘cortical’ plate
What is a nutrient foramen?
A small tunnel through the cortex of the bone containing a nutrient artery which supplies the bone
What is the lamina dura?
- A layer of the alveolar bone that is thin and particularly compact and appears as a line on dental x-rays
When teeth are lost, the alveolar process is resorbed, what does this leave?
- A residual ridge
The periodontal ligament is a connective tissue. What are the 5 things it contains?
- Cells
- Extracellular matrix
- Fibres
- Nerves
- Blood vessels
What is contained within the matrix of the PDL?
- Hyaluronate GAG’s
- Glycoproteins (fibronectin)
- Proteoglycans (proteodermatan sulphate, ch ondroitin/dermatan SO4 hybrid)
What is the property of the matrix of the PDL?
Behaves as a viscoelastic gel
What are the cells of the PDL? (5 points)
- Fibroblasts
- Cementoblasts
- Osteoclasts and Cementoclasts
- Epithelial cells (cell rests of Malassez)
- Defence cells
What are the cell rests if Malassez?
Epithelial cells in the PDL derived from Hertwig’s epithelial root sheath. They can proliferate in the presence of inflammation, possibly leading to cyst formation
What 2 types of mechanoreceptors are found in the PDL?
A-beta and A-delta fibres
What is the function of mechanoreceptors in the PDL?
Proprioception - controls chewing
What 2 types of nociceptors are found in the PDL?
A-delta fibres and C fibres
What are the functions of nociceptors in the PDL? (2 points)
- Protective reflexes
- inhibit jaw elevator motor neurons
What is the function of autonomic nerves in the PDL?
- For blood vessel control (vasoconstriction)
Which arteries supply the PDL?
- Inferior and superior alveolar arteries - from the alveolar bone
What is the name of the inner alveolar bone and what does it contain?
- Inner Cancellous bone
- Contains marrow
Which arteries supply the gingivae?
Lingual and palatine arteries
What is meant by ‘true’ periodontal ligament?
- Fibres connecting tooth to bone at or apical to the alveolar crest
What is ‘gingival’ PDL?
- Fibres mainly above the alveolar crest, including ‘free gingival’ fibres
(the free gingival fibres arise from the surface of the cementum in the cervical region and pass into the free gingiva)
In between each group of PDL fibres is a space termed the interstitial space which is not actually a space. What does the intersti t ial space contain that maintains the vitality? (3 points)
- blood vessels
- nerves
- Lymphatics
What type of force does the PDL transmit to the alveolar bone?
Biting forces
What is the width of PDL?
Approx. 0.2mm
What types of collagen fibres are present in the PDL? (2 points)
Types I and III
What is the function of collagen fibres in the PDL?
- supports tooth; load bearing
What are the 3 types of fibre in the PDL?
- Collagen
- Oxytalan
- Elastic
Are oxytalan fibres present in human PDL?
Yes
What is the function of oxytalan fibres in the PDL?
Function is uncertain
Are elastic fibres present in human PDL?
No
What are the different PDL fibre groups in the alveolo-dental ligament? (5 points)
- Alveolar crest
- Horizontal
- Oblique
- Apical
- Interradicular (multi-rooted teeth)
What is the PDL fibre group for interdental ligament?
- Transseptal fibres
What do Transseptal fibres of the PDL connect from and to?
- Connecting tooth to tooth
- Not connecting to bone
What is the function of the gingival fibre group?
- Supports the free gingiva
What are the 4 types of marginal gingiva?
- Dento-gingival
- Alveolo-gingival
- Dento-periosteal
- Circular
What is PDL loading?
- The application of brief forces
Teeth are rarely subjected to extrusive and horizontal forces. What are 2 examples of these?
- Sticky foods
- Orthodontic forces
The PDL is mostly subjected to intrusive forces. What are 4 examples of these?
- Mastication
- Swallowing
- Speech
- Parafunction (e.g. clenching, grinding)
Why is the interdental col non-keratinised?
- Because there are no masticatory forces
What is an interdental col?
- A craterlike area of the interproximal oral mucosa joining the lingual and buccal interdental papilla
- It is the area between 2 teeth that is protected by the contact point
What is the name of the nutrient canals that penetrate the alveolar bone?
- Volkmann’s canals
What are the functions of alveolar bone? (2 points)
- Provide attachment for periodontal ligament fibres
- Supports the teeth
What are the periodontal tissues? (4 points)
- Gingiva
- Cementum
- Alveolar bone
- Periodontal Ligament
