(1) Anatomy and Histology of the Periodontium - periodontal ligament (Fibres) Flashcards
Where is the periodontal ligament found?
occupies the space between the alveolar bone and the cementum (root section)
How would you describe the periodontal ligament?
dense fibrous connective tissue
What 2 tissues is the periodontal ligament continuous with?
Continuous with the gingival connective tissue and the pulp.
What varies in the periodontal ligament?
Variation in width; location, function and age.
What causes the variation in the width of the periodontal ligament?
location, function and age.
Is the PL narrower in primary or permanent teeth?
permanent
according to health status and function
What type of section is shown?
decalcified
How many teeth would be associated with the section shown?
2
Name sections A-D
What are 4 functions of the periodontal ligament?
1) Provision of the tissue attachment between the tooth and alveolar bone. Thus is responsible of tooth support and protection.
2) Responsibility for the mechanism by which the tooth attains and maintains its functional position.
3) Maintenance and repair of cementum and alveolar bone.
4) Neurological control of mastication by its mechanoreceptors.
What are the 3 component of the periodontal ligament?
- fibres
- ground substance
- cells
What 2 fibres are found in the periodontal ligament?
collagen
oxytalan
What is ground substance?
It is transparent, colourless, and fills the spaces between fibres and cells. It actually consists of large molecules called glycosoaminoglycans (GAGs) which link together to form even larger molecules called proteoglycans.
What cells are found in the periodontal ligament?
fibroblasts, cementoblasts, osteoblasts, osteoclasts, cementoclasts, epithelial cells and immune cells
What is the main fibre in the periodontal ligament?
collagen
What is the most abundant type of collagen in the PL?
Type I
(70%)
What is the second most abundant type of collagen in the PL?
Type III (20%)
What are the less abundant types of collagen in the PL?
Types V and VI
Where are there traces of types IV and VII in the PL?
rests of malassez and blood vessels
What does collagen form in the PL?
principal fibres
Compare the attachment of principal fibres with the cementum and the alveolar bone?
Principal fibres are more numerous but smaller at their attachment with cementum in comparison to alveolar bone.
What are collagen fibres in the principal fibre?
Collagen fibrils are subunits within each principal fibre.
Name 5 of the principal fibres according to their orientation
1) Dentoalveolar crest fibres.
2) Horizontal fibres.
3) Oblique fibres.
4) Apical fibres.
5) Interradicular fibres.
Name principal fibres A-D
Name principal fibres A-E
What ligament is shown at A?
What are sharpey’s fibres?
Sharpey’s fibres are the collagen fibres inserted into cementum and bone.
What course do the principal fibres have?
wavy course
What is the turnover of collagen like in the PL?
Fast turnover of collagen in periodontal ligament.
Where is collagen turnover the fastest?
root apex
Describe Sharpey’s fibres at the cementum?
More numerous and smaller at the cemental attachment.
What is oxytalan?
Immature elastin fibres (pre-elastin).
What percent does oxytalan have of the overall PL fibre composition?
3%
Where do the oxytalan fibres attach to?
the cementum
Do oxytalan fibres incorporate into bone?
rarely
What dictates the orientation of the oxytalan fibres?
location
Where do oxytalan fibres terminate?
around blood vessels and nerves
Found mainly around the cervical region, running parallel to collagen fibres
Name fibres A and B?
A = oxytalan
B = collagen
Are oxytalan fibres banded or unbanded?
unbanded
What is the role of oxytalan fibres?
not known
but likely…
Aid in fibroblast migration within the ligament
Role in tooth support
What are the rests of malassez?
The epithelial rests of Malassez (ERM) represent a group of cells in the periodontal ligament classically consisting of latent or quiescent structures associated with pathological processes.
Help repair and maintain homeostasis of the periodontal ligament
What is shown in this decalcified section?
Rests of malassez