Regeneration And Repair

Question 1

What is regeneration?

What is repair?

Answer 1

Regeneration - Complete restoration of tissue architecture and fx (good as new)

Repair - Restoration of fx, BUT altered architecture (scars)

Question 2

What are the 4 phases of tissue repair?

Answer 2

Hemostasis - Clot formation

Inflammatory - Infiltration of immune cells and initiation of repair

Reparative (Proliferative) phase - Migration of cells and formation of granulation tissue

Wound contraction and scarring (not always though)

Question 3

What is hemostasis?

Answer 3

Liquid blood to fibrillar gel

Primary goal - STOP the bleeding

Secondary goal - INITIATE healing

Question 4

_________ of platelets leads to coagulation cascade.

Answer 4

Disruption

*Clot unites edges of wound, and FIBRIN provides a scaffold for future cell migration

Question 5

T/F - Clot is different in the oral cavity. It is softer and more easily detached.

Answer 5

TRUE

Question 6

What is Von Willebrand disease?

Answer 6

Lack of the Von Willebrand Factor
-This factor causes platelet aggregation by interacting with platelet surface proteins
—*THIS IS PROMINENT IN PRIMARY HEMOSTASIS

Question 7

What is primary hemostasis?

Answer 7

Vascular spasm (constriction) and initial platelet plug in a damaged blood vessel

Question 8

Platelets bind collagen directly via what 2 things?

Answer 8

GPVI
-Glycoprotein VI

Alpha2beta1 integrin

Question 9

When does secondary hemostasis occur?

Answer 9

Simultaneously with primary hemostasis or just after primary

Question 10

Secondary hemostasis has two pathways.

Answer 10

Extrinsic

Intrinsic

Question 11

Tell me about extrinsic.

Answer 11

Factor VII and tissue factor interactions and that initiates the cascade

• Called extrinsic b/c it req’s tissue factor which is normally NOT found in blood

Question 12

Tell me about intrinsic.

Answer 12

Initiated by damaged endothelium (due to collagen exposure)

• Called intrinsic b/c it involves factors found in the blood, not tissue factor

Question 13

What is the main point of both pathways?

Answer 13

Conversion of prothrombin into thrombin, which converts soluble fibrinogen into insoluble fibrin

*Ca2+ is req’d at many steps

**Fibrin cross-links and forms a mesh, trapping RBCs and WBCs, resulting in a blood clot

Question 14

What WBCs are first on the scene?

Answer 14

PMNs

Question 15

What WBCs are second to arrive?

Answer 15

Macrophages

-Clear damaged tissue and foreign material

Question 16

What are the main leukocytes involved?

Answer 16

T cells in particular

Question 17

What happens in the reparative/proliferative phase?

Answer 17

Mobilization of adj cells (epithelium)

Cells migrate under fibrin clot - forming a “granulation tissue”

Question 18

Collagen type IV is found where?

Answer 18

BASAL LAMINA

Question 19

When epithelial cells migrate, what do they form?

Answer 19

New basal lamina

*Also redistribution of integrin receptors and formation of new hemidesmosomes

Then, fibroblast recruitment occurs, and proliferation of fibroblasts in the wound. Collagen fills the defect, forms a scaffold

Question 20

What is angiogenesis?

Answer 20

Regeneration of blood vessels

*TGFbeta, VEGF, FGF-2 are factors important in healing the wound and blood vessels

Question 21

What cells do wound contraction?

Answer 21

Myofibroblasts

Question 22

What do myofibroblasts do?

Answer 22

Align around wound, form cell junctions, and attach to connective tissue fibrin around wound (like a purse string)

Wound is drawn together

Question 23

Oral mucosa is typically not scarred. Why?

Answer 23

No one really knows

Question 24

If the source of inflammation is removed in periodontal disease, the formation of what stimulates reattachment of connective tissues?

Answer 24

Fibrin clot

Question 25

Gingivitis?

Periodontitis?

Answer 25

Gingivitis - Repair will occur once infection is removed

Periodontitis - Involvement of alveolar bone, much less change of successful repair.

Question 26

What are the 3 primary zones of dental caries?

Answer 26

Surface and body - surface zone remineralizes, body is primary zone of demineralization

Dark zone - zone of increasing demineralization

Translucent zone - leading edge - causes by micro-pores which form in the enamel rod boundaries

Question 27

T/F - Caries are dynamic with continual de-mineralization and re-mineralization, but a net loss.

Answer 27

TRUE

Question 28

What is a dentin bridge?

Answer 28

Dentin formed b/t surviving dentin and restorative material, preventing “micro leakage”

-Biomaterials which induce OD differentiation and dentin production = more rapid dentin bridge

Question 29

What are the 3 key components in tissue engineering?

Answer 29

Cell source

Material

Bioactive component

Question 30

What is reactionary dentin?

What is reparative dentin?

Answer 30

Reactionary - Trauma does NOT damage ODs

Reparative - Trauma DOES damage ODs

Tertiary (sclerotic) dentin formation

Question 31

Cellular and acellular approaches to tooth repair.

Answer 31

Advantages and disadvantages to each

Tissues need cells to regenerate, but many contain cells containing the necessary cells

Cellular
-Addition of material containing cells

Acellular
-Materials to existing tissues