Periodontium Flashcards
What’s the components of PDL ?
PDL complex , specialized , soft and fibrous CT .
Contain Cellular ellements
Blood vessels and nerves .
Extracellular matrix
-Fibers ( gingival + principle ) collagen.
-Ground substance ( various proteins and polysaccharides)
Whats main four types of cells ?
-connective tissue cells,
-epithelial rest cells,
-immune system cells,
-cells associated with neurovascular elements.
What’s CT cells ?
- Synthetic cells-
Cementoblasts are seen lining the cementum
Osteoblasts
Fibroplasts - Resorptive Cells
Osteoclasts:
Cementoclasts:
Fibroblasts
3.Progenitor cells
What’s epithelium cells ?
Epithelial cell rests of Malassez- remnants of Hertwig’s epithelial root sheath
Found in PDL some of them degenerate, others become cementicles ( calcified ).
Where does osteoblasts found ?
Cover the periodontal surface of the alveolar bone
What’s the main function of fibroblasts ?
synthesize collagen
possess the capacity to phagocytose old” collagen fibers
• Collagen fibers
• Reticulin fibers
• Oxytalan fibers
• Elastin fibers
What’s osteoclasts ?
resorb the bone. The precursor cells of the osteoclasts are circulating monocytes
Does cementum undergo any remodeling?
No , it in continued deposition during life in some cases undergo resorption by cementoclasts in howship’s lacunae
Which cells seen in the cemental and osseous surfaces of the periodontal ligament ?
Osteoblasts and cementoblasts,
osteoclasts and cementoclasts,
Whats Progenitor cells ?
( Mesnchymal stem cells ) daughter cell after the division -differentiates into the functional type of connective tissue cells. Either cementoblasts , fibroblasts , osteoblasts.
What’s the components of extracellular components the fiber and ground substances ?
- Fibers:
• Collagen
• Oxytalan - Ground substance:
• Proteoglycans
• Glycoproteins
water content (70%).
What’s the terminal portion of PDL fibers that connect to cementum and bone ?
Sharpey’s fibers.
What’s the principal fibers of periodontal ligament ?
Trans-septal group
Alveolar crest,
horizontal,
oblique,
apical
Interradicular fibers
Which structures found in CT ?
- Blood vessels
- Lymphatics
- Nerve innervation
- Cementicles
Which branches supply the PDL ?
dental(apical)
inter-radicular and
interdental arteries
Which the main arteries and nerves supply PDL ?
dental branches of the inferior alveolar
and branches of maxillary nerve through the apical perforations of the tooth socket ** OR ** from the compact plate.
What’s the function of nerve supply to PDL ?
touch, pressure, pain, and proprioception during mastication.
What’s cementicles ?
calcified masses ( round or oval ) adherent to or detached or embeded near the root ( cementum ) surface .
calcified epithelial rests,
calcified Sharpey’s fibers,
Calcified thrombosed vessels within the periodontal ligament.
What’s PDL functions ?
- Physical ( support , protect )
- Formative and remodeling ( resorption )
- Nutritional and sensory ( trigminal nerve ) function.
All of this for the teeth
What’s is periodontium ?
Gingiva , PDL , cementum , alveolar bone , supporting bone .
What’s attachment apparatus?
Alveolar bone , PDL fiber , cementum that attach the teeth to bone.
What’s gingival apparatus ?
Gingival fibers and epithelium , and ligaments
What’s the PDL fibers ?
Hour glass shape narrow at the midddle.
What’s happen to PDL when they tooth loss it’s function ?
Become very thin and irregular arrangement of fibers.
Which cells most to be abundant ?
Fibroblasts ovoid spindle-like oriented along PDL principle fibers
How sensory ( nerve ) function of PDL done ?
Caries by trigeminal nerve from CNS .
Proprioceptive تحسس and tactile لمس sensitivity is imparted through PDL ( sensation of contact between teeth ) .
2 types of nerve ending ::
1. Free end unmyelinated»_space;> pain. ( Ruffini like mechanoreceptors at apex , meissners corpuscle at the middle )
- Encapsulated myelinated nerve ending ( spindle like ) »_space;> pressure it’s why patient tell you I fell pressure below my teeth
It’s why when infection envolve the periapical become more easy to detect the causative teeth.
How PDL used in orthodontics ?
If the movement of the tooth is within physiological limits,
the compression on pressure side results in bone resorption,
on the tension side bone apposition is seen.
Application of the large forces results in the necrosis of periodontal ligament and alveolar bone.
PDL thickness in adults 0.25mm how it change during aging ?
PDL become thinner , decrease thickness , due to deposition of cement and bone espicially in mandibular canine region.
How does tooth function affect PDL thickness?
It’s more thick in functional teeth than non .
Thicker in tension area , than compression .
How trauma effect PDL in 2 ways ?
any trauma to the periodontal ligament can result in the loss of alveolar bone and widening of ligament but once the trauma is removed, repair usually takes place.
In trauma history , PDL not exist due to ankylosis ( fusion of tooth to bone ).
What’s happen when gingival inflammation spread to PDL ?
destruction of periodontal structures will result, which is difficult to regenerate, hence the disease of periodontal ligament are often irreversible.
PDL composed mainly from collagen type 1 fibers what about elastin fibers ?
Doesn’t contain mature elastin but contain the immature one ( oxytalan , eluanin ).
Oxytalan : parallel to root surface bend to attach to cementum in cervical third of root.
Regulate blood flow.
PDL are specialized form of CT derived from dental sac , composed mainly from collagen type 1 fibers arranged in 2 groups what’s this groups ?
Gingival fibers ( some times considered as PDL principle fibers )
Principle fibers of PDL
