Periodontal Ligament Flashcards
(49 cards)
Enumerate the different cells of the periodontal ligament.
- Fibroblasts
- Undifferentiated cells
- Macrophages
- Epithelial rests of Malassez
- Bone cells*
- Cementoblasts*
- Cementoclasts (only when cementum is undergoing absorption)*
Why are bone cells and cementoblasts part of the PDL?
Because of their location
What are the functions of fibroblast?
They maintain collagen fibers and ground substance of the PDL
They synthesize and degrade collagen
Describe a periodontal fibroblast.
They have extensive processes that wrap around collagen fiber bundles
They have a cytoskeleton and an actin network.
What is the function of the cytoskeleton and actin network of a periodontal fibroblast?
They can change shape and can move; This helps in eruption
What is the function of undifferentiated cells?
They are the source of replacement cells
What is the function of macrophages?
They are defense cells.
They are mobile and phagocytic. They eat up dead cells and bacteria.
What are the possible functions of the epithelial rests of Malassez?
Regeneration of periodontal tissues
What cell in the periodontal ligament is possibly involved in the formation of enamel pearls?
Epithelial rests of Malassez
Explain why the epithelial rests of Malassez are vital but resting cells.
They contain a few mitochondria and poorly developed endoplasmic reticulum
What is formed in the epithelial lining if a PDL gets inflamed?
Dental cysts
What cells are part of the periodontal ligament only because of their location?
- Bone cells (osteoblasts, osteoclasts)
- Cementoblasts
- Cementoclasts (only when cementum is undergoing resorption)
Enumerate the main components of the intercellular substance of the periodontal ligament.
- Collagen fibers
- Elastic fibers (oxytalan)
- Ground substance
What is the composition of the ground substance of the periodontal ligament?
(similar to that of the pulp)
- Glycoproteins
- Glycosaminoglycans
- 70% water
Why is the ground substance of the periodontal ligament composed of 70% water?
To help tooth withstand stress loads
What is the function of oxytalan in the periodontal ligament?
Associated with nerve fibers and blood vessels
Regulate blood flow
What is the function of collagen fibers?
- Remodeling without affecting tooth support
- Physiologic mobility (allows tooth to move within socket)
How come collagen fibers have physiologic mobility?
Individual fibers have a slightly wavy course; Hindi sila straight and stiff
What are the five principal collagen fiber groups of the periodontal ligament? Imagine their location in the tooth and try to identify in histologic preparations.
What do you call the bundles of collagenous fibers in the periodontal ligament?
(Part of the periodontal ligament embedded in cementum and alveolar bone)
Sharpey’s fibers
Differentiate collagen fibers from elastic fibers in terms of location and function.
Collagen fibers: embedded in cementum and alveolar bone; physiologic mobility
Elastic fibers: location (?); regulate blood flow
What arteries are involved in the blood supply to the periodontal ligament?
Superior and inferior alveolar arteries
Identify the three sources of blood supply of the periodontal ligament and imagine their locations.
Coronally (from gingiva)
Laterally (from bone); branches out when entering the periodontal ligament’s face (1) occlusally and (2) apically
Apically (before entering apical foramen to supply pulp)
Compare and contrast the repair potential of the periodontal ligament and the pulp.
Since PDL has three sources of blood supply and pulp only has one (from apical foramen), when something happens to one blood supply, pulp will die but PDL would still have two other sources. (It will only have chronic diseases.)
