Periodontium II

Question 1

What are the origins of cementum?

Answer 1

HERS

• Can detach = Rest cells of Malassez
• Can contribute to dentin

-Can induce follicle cells->cementoblasts->secrete cementum matrix (cementoid)->mineralized cementum

Question 2

What is the composition of cementum?

Answer 2

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

Question 3

Cells in the ______ ______ become cementoblasts.

Answer 3

Dental follicle

Question 4

How is cementum formed?

Answer 4

HERS OR DENTIN INDUCES CELLS IN THE DENTAL FOLLICLE TO BECOME CEMENTOBLASTS

Question 5

HERS cells that break off become what?

Answer 5

Rest cells of Malassez

Question 6

HERS cells that remain attached to roots can form what?

Answer 6

Enamel pearls

Question 7

CEJ

3 types of joints. Name and describe them with %’s.

Answer 7

Overlap - 60% - Cementum overlaps enamel

Butt - 30% - Meet at CEJ

Gap - 10% - Do not touch (Exposed dentin)

Question 8

What are the two types of cementum?

Answer 8

Acellular - Primary

Cellular - Secondary

Question 9

Extrinsic collagen fiber origin?

Intrinsic collagen fiber origin?

Answer 9

Extrinsic - PDL

Intrinsic - Cementoblasts themselves

Question 10

Acellular has ________ fibers. Cellular has ________ fibers.

Answer 10

Extrinsic

Intrinsic

*”IN THE CELL” (Intrinsic = cellular)

Question 11

Which type of cementum makes up the coronal 2/3rds of the root?

Answer 11

Acellular extrinsic cementum OR Primary cementum

Question 12

Which type of cementum makes up the apical 1/3rd of the root?

Answer 12

Cellular intrinsic cementum OR Secondary cementum

Question 13

Tell me the difference between Acellular extrinsic fiber cementum (AEFC) and Cellular intrinsic fiber cementum (CIFC).

Answer 13

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

Question 14

What is intermediate cementum?

Answer 14

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)

Question 15

What is mixed cementum?

Answer 15

Alternating layers of AEFC and CIFC

Extrinsic and intrinsic fibers, generally located apically

A lot of secondary cementum is mixed

Question 16

What is hypercementosis?

Answer 16

ABNORMAL thickening of cementum

Can affect entire dentition, or single tooth

TOOTH CAN BECOME ANKYLOSED

Question 17

***T/F - CEMENTUM IS MORE RESISTANT TO RESORPTION THAN ALVEOLAR BONE.

Answer 17

TRUE

*This allows teeth to move thru bone

Question 18

What are the 2 forces on a moving tooth?

Answer 18

Tension

Compression (The side its going to)

Question 19

What are 5 tooth movements?

Answer 19

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

Question 20

What are 3 factors that affect tooth movement?

Answer 20

Transduction
-Conversion of physical force into biologic response

Time
-Effect is time-dependent

Magnitude of force
-Degree of force determines response

Question 21

What are 4 net results of tooth movements?

Answer 21

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