Periodontium 2 Flashcards
Cementum is a ___________ tissue.
Hard connective tissue
What are the 3 main functions cementum?
- attach tooth to jaw
- protect root dentin
- adapting to the forces of mastication
What is the Chemical composition of cementum?
Similar to bone 45-50% organic and 50-555 inorganic.
*Major component of Inorganic matrix is hydroxyapatite.
In what 2 major ways does cementum differ from bone?
- It is NOT vascularized
2. IT does not remodel (resistant to reabsorption)
What is the thickness of cementum?
@ CEJ = 20-50um
Toward root apex = 150-200um
Describe the relationship between enamel and cementum…
- Cementum overlaps enamel about 60% of the time.
- Cementum and enamel butt together about 30% of the time.
- 10% of the time there is a gap between the two.
- Cervical
- Acellular extrinsic fibers
- More mineralized
- more important in attachment
WHAT AM I?
Primary cementum
- Apical
- Cellular intrinsic & Mixed fibers
- Less mineralized
- More important in adaptation of masticatory forces.
Secondary cementum
What is the main collagen of cementum?
Type 1 (90%) type 3 (10%)
The collagen matrix of acellular cementum consists of fibers oriented in what direction?
@ right angles to the cementum surface.
The collagen matrix of cellular intrinsic fiber cementum consists of fibers oriented in what direction?
Parallel to surface of cementum
What are the two kinds of secondary cementum?
cellular intrinsic fiber cementum
Mixed fiber cementum = Bulk of secondary cementum that is typically secreted after and more slowly that cellular cementum so it is more prominent in apical portion of tooth.
Cementocytes were once ________.
Cementoblasts, until they were trapped in the mineralized extracellular matrix.
T or F, Cementocytes are no longer involved in synthesizing cementum.
True
If cementum is laid down throughout life, and cementocytes don’t synthesize cementum, where does it come from?
Cementoblast lying at the edge of the adult PDL
