PDL Flashcards
General characteristics of the PDL
Soft CT composed of collagen
Principle fibers of periodontium
Sharpey’s fibers= terminal ends of principle fibers
What are the functions of the PDL?
Supportive Nutritive Formative Protective Sensory Hemostatic Eruptive movement
What are the supportive functions of PDL?
Supports root in alveolus & resists forces
What are the nutritive functions of PDL?
Carries nutrients to cementum, ABP and PDL
What are the formative functions of PDL?
Forms and resorbs cementum, ABP and PDL
What are the protective functions of PDL?
Shock absorber for BV, lymphatics and nerves
What are the sensory functions of PDL?
Pain, touch, temp and proprioceptive
What are the hemostatic functions of PDL?
Maintains constant width of PDL space
What are the eruptive movement functions of PDL?
Assists in eruptive movement
Where is the PDL located? Where is it widest and thinnest?
Located between the ABP and cementum
Widest at alveolar crest and apex, thinest at midpoint of root
Thin, limited space, narrows with age
What is the embryonic origin of the PDL?
Neuroectoderm/Neural crest cells of the head and neck
Ectomesenchyme of neural crest cells give rise to dental sac–> dental sac/follicle gives rise to fibroblasts that form the principle fibers of the PDL
What cells is the PDL composed of?
Fibroblasts (most abundant) Mesenchyme cells Cementoblasts Osteoblasts Cell rests of Malassez
Additional cells: mast, macrophages, lymphocytes, plasma cells
Fibroblasts function in PDL
Produce/resorb collagen, maintains PDL fibers and space
Produces ground substance
Function of mesenchyme cells in PDL
Form fibroblasts, cementoblasts, osteoblasts
Where are cementoblasts found in PDL?
Closest to cementum
Where are osteoblasts found in PDL?
Closest to ABP
Where are cell rests of Malassez located in PDL and what is their function?
Found closest to the cementum
May participate in PDL repair/regeneration- potential to form cysts
What are the 5 principle fibers of the PDL?
Alveolar crest fibers 1st group Horizontal fibers 2nd group Oblique fibers 3rd group Apical fibers 4th group Interradicular fibers 5th group
Where are alveolar crest fibers located and what types of forces do they resist?
Apex of alveolar crest to cementum at cervix of root
Resists tilting, occlusal, avulsive and rotational forces
Where are horizontal fibers located and what types of forces do they resist?
Extend horizontally from ABP to cementum just apical to alveolar crest fibers- coronal 1/3 of root
Resist tilting and rotational forces
Where are oblique fibers located and what types of forces do they resist?
Largest group
Extend obliquely from ABP to cementum just apical to horizontal fibers- mid portion of root to apical 1/3
Acute angle to horizontal fibers
Most resistant to occlusal and some rotational forces
Where are apical fibers located and what types of forces do they resist?
Extend from apical ABP to apical cementum- parallel with long axis of root
Resistant to avulsive and rotational forces
Where are interradicular fibers located and what types of forces do they resist?
*only in multi rooted teeth
Extend from apex of interradicular septum ABP to cementum of furcation area
Resist tilting, occlusal, avulsive, and rotational forces
What are oxytalan fibers? Where are they located?
Support the BV and alleviate some masticatory stress on the BV
Positioned in various angles to principle fibers
