Periodontium II Flashcards
What are the origins of cementum?
HERS
- Can detach = Rest cells of Malassez
- Can contribute to dentin
-Can induce follicle cells->cementoblasts->secrete cementum matrix (cementoid)->mineralized cementum
What is the composition of cementum?
Very similar to bone
Thinner at CEJ: 20-50 microns
Thicker at apex: 150-200 microns
50% Inorgo: HA
50% Orgo: 90% Type I collagen
- Types III, and XII also present
- Also some bone-associated non-collagenous proteins are present
Cells in the ______ ______ become cementoblasts.
Dental follicle
How is cementum formed?
HERS OR DENTIN INDUCES CELLS IN THE DENTAL FOLLICLE TO BECOME CEMENTOBLASTS
HERS cells that break off become what?
Rest cells of Malassez
HERS cells that remain attached to roots can form what?
Enamel pearls
CEJ
3 types of joints. Name and describe them with %’s.
Overlap - 60% - Cementum overlaps enamel
Butt - 30% - Meet at CEJ
Gap - 10% - Do not touch (Exposed dentin)
What are the two types of cementum?
Acellular - Primary
Cellular - Secondary
Extrinsic collagen fiber origin?
Intrinsic collagen fiber origin?
Extrinsic - PDL
Intrinsic - Cementoblasts themselves
Acellular has ________ fibers. Cellular has ________ fibers.
Extrinsic
Intrinsic
*”IN THE CELL” (Intrinsic = cellular)
Which type of cementum makes up the coronal 2/3rds of the root?
Acellular extrinsic cementum OR Primary cementum
Which type of cementum makes up the apical 1/3rd of the root?
Cellular intrinsic cementum OR Secondary cementum
Tell me the difference between Acellular extrinsic fiber cementum (AEFC) and Cellular intrinsic fiber cementum (CIFC).
AEFC
- NO cells inside
- NO cementoid
- SLOW deposition
- MORE mineralized
- Fx: Attach PDL to cementum
CIFC
- More laminar
- Encapsulated cells
- Cementoid visible
- OFT ABSENT in canines and incisors
- Fx: Adaptation and adj for wear, some attachment
What is intermediate cementum?
B/t granular layer of Tomes and dental cementum proper
High level of mineralization
May fx to seal the surface of root dentin (which reduces sensitivity)
What is mixed cementum?
Alternating layers of AEFC and CIFC
Extrinsic and intrinsic fibers, generally located apically
A lot of secondary cementum is mixed
What is hypercementosis?
ABNORMAL thickening of cementum
Can affect entire dentition, or single tooth
TOOTH CAN BECOME ANKYLOSED
***T/F - CEMENTUM IS MORE RESISTANT TO RESORPTION THAN ALVEOLAR BONE.
TRUE
*This allows teeth to move thru bone
What are the 2 forces on a moving tooth?
Tension
Compression (The side its going to)
What are 5 tooth movements?
Tipping - Compression and tension happening simultaneously and a diagonal line can be drawn across the tooth connecting the matching forces
Bodily movement - One way - One side compressed, other is tensed
Extrusive movement - Towards oral cavity
Intrusive movement - Towards alveolus
Rotational movement - Clockwise or counter
What are 3 factors that affect tooth movement?
Transduction
-Conversion of physical force into biologic response
Time
-Effect is time-dependent
Magnitude of force
-Degree of force determines response
What are 4 net results of tooth movements?
Compression
- On the side to which the tooth moves
- Resorption of alveolar bone
Tension
- On the side opposite to compression
- Formation of alveolar bone
Hyalinization
-Too great or too rapid a compression force
—Loss of cell activity and vascularity
Undermining resorption
- Occurs with hyalinization
- Resorption occurs on the opposite surface of compressed bone
