Wound healing

Question 1

Briefly describe the physiology of blood clotting.

Answer 1

Read page 27-28 on document (old written doc)

Anson: what kind of question is this.. Doesn’t specify marks either

Question 2

What are the medical causes for prolonged wound healing?

Answer 2

Diabetes mellitus, keloids, fibrosis, hereditary healing disorders, jaundice, uremia

Question 3

State two investigations that can be taken for DM and hereditary bleeding disorder

Answer 3

• Glucometer for DM (Ken: HbA1c?)

* PTT, PT, platelet test, TT (hereditary bleeding disorder)

Question 4

List 4 factors that affect wound healing (2)

Answer 4

Oxygenation, infection, age and sex hormones, stress, diabetes, obesity, medications, alcoholism, smoking, and nutrition

Question 5

What is acute inflammation? List the clinical signs for acute inflammation (2.5)

Answer 5

short-term process occurring in response to tissue injury, usually appearing within minutes or hours

Ken:
A localized protective response elicited by injury or destruction of tissues, which serves to destroy, dilute, or wall off both the injurious agent and the injured tissue

5 signs: pain, redness, swelling, heat, loss of function

Question 6

Functional process of the neutrophils during bacterial infection (2.5)

Answer 6

Activated tissues at the site of inflammation release cytokines

These cytokines attract neutrophils to move to area of infection, via a chemotactic gradient. They move by chemotaxis

Phagocytosis – engulf bacteria and kill them

Degranulation – release cytokines and other signals to signal other cells and inflammation and kill bacteria.

Question 7

Name the cells involved in soft tissue wound healing & their respective functions (2)

Answer 7

White blood cells – inflammatory response, recruit other cells, prevent infection

Mast cells – inflammatory response, prevent infection

Fibroblasts – granulation tissue formation

Question 8

What is the major difference between healing by repair & regeneration (2 or 3)

Answer 8

Repair: unspecific form of healing in which the wound heals by fibrosis and scar formation.

Regeneration: specific substitution of the tissue, i.e. the superficial epidermis, mucosa or fetal skin

Ken:
Repair: it is healing by proliferation of CT elements resulting in fibrosis and scarring

Regeneration: It is healing by proliferation of parenchymal cells, results in complete restoration of the original tissue

Question 9

What are the histological appearance of the gingival tissue after scaling and root planing? (3)

Answer 9

• Partial removal of sulcal epithelium
• Tearing and splitting of rete pegs
• Occasionally, underlying connective tissue may be injured
• (All heals within 1 week + destruction depends on severity of inflammation)

Question 10

Describe the healing of the extraction socket immediately after operation until it is fully healed (5)

Answer 10

Immediately (Socket filled with blood and blood clot formation occurs)

0-1 week (Almost all blood clot remodeled and replaced by granulation tissue)

After 1st week (Deposition of mineralized tissue begins)

2-4 weeks (No more blood clots + Erythrocytes scattered between mensenchymal cells + Granulation tissue and provisional matrix are 30-50% of total tissue filling the socket)

6-8 weeks (Most of GT is replaced with provisional matrix (60%) and woven bone (35%) + Margin of socket of has immature woven bone)

12-24 weeks (Provisional matrix and woven bone (lamellar bone may still not fully form yet!) + should see some lamellar bone

Question 11

What are blood clot, granulation tissue, provisional matrix, woven bone and lamellar bone and marrow?

Answer 11

• blood clot (BC), consisting of erythrocytes and leukocytes embedded in a fibrin network;

Question 12

What is granulation tissue?

Answer 12

• granulation tissue (GT), rich in newly formed vascular structures, inflammatory cells and erythrocytes;

Question 13

What is provisional matrix?

Answer 13

• provisional matrix (PM), presenting densely packed mesenchymal cells, collagen fibers and vessels but no or only scattered inflammatory cells;

Question 14

What is woven bone?

Answer 14

• woven bone (WB), consisting of fingerlike projections of immature bone embedded in a primary spongiosa;

Question 15

What is lamellar bone and marrow?

Answer 15

• lamellar bone and marrow (LB/BM), i.e. lamellae of mature, mineralized bone harboring secondary osteons surrounded by marrow spaces rich in vessels, adipocytes, mesenchymal cells and inflammatory cells.

Question 16

List some factors influencing the healing of extraction sockets

Answer 16

1. Smoking – 0.5mm more bone loss than non-smokers
2. Flapless tooth extraction (flapless = less bone reduction)
3. Location of edentulous site (more resorption in molars than premolars)
4. Single versus multiple extraction (more resorption in multiple adjacent edentulous sites than single-tooth)
5. Chlorhexidine mouthrinse following tooth extraction (0.06mm bone reduction with CHX for 30 days; 1mm bone reduction without CHX)

Question 17

What is ‘dry socket’?

Answer 17

Dry socket
• an acute inflammation of the alveolar bone around the extracted tooth and it is characterized by severe pain, breakdown of the clot formed within the socket making the socket empty (devoid of clot), and often filled with food debris. There is mild swelling and redness of the gingivae, halitosis, bone exposure, and severe tenderness on examination.

Question 18

What is the pathophysiology of dry socket?

Answer 18

• Fibrinolytic theory: “Birn hypothesized that trauma during an extraction or the presence of a bacterial infection somehow facilitates the release of plasminogen tissue activators in the post-extraction socket, resulting in the plasmin induction of fibrinolysis that dislodges the blood clot that formed after the extraction and causing a dry socket lesion”

Question 19

What is the alternative theory of the pathophysiology of dry socket?

Answer 19

• Alternative theory: high compressive forces on alveolar bone surrounding the tooth –> necrosis of osteoblast on surface of extraction area (24-96 hrs) –> initiate fibrinolytic activity that lyses blood clot OR necrotic osteoblasts cannot integrate into blood clot leading to blood clot dislodgment.
• (There is evidence that reduced post-extraction socket blood flow facilitates dry socket lesion formation.)

Question 20

List some predisposing factors of dry socket.

Answer 20

• Surgical trauma and difficulty of surgery
• Lack of operator experience –> more trauma
• Mandibular third molars
• Systemic disease (maybe diabetics and the immunocompromised..)
• Oral contraceptives
• Gender – female px have higher risk
• Smoking
• Physical dislodgment of the clot (e.g. sucking on straw, but no evidence…?)
• Bacterial infection
• Excessive irrigation or curettage of alveolus
• Age of patient (older px has a higher risk)
• LA with vasoconstrictor
• Bone/root fragments remaining in the wound
• Flap design/Use of suture

Question 21

What are the treatments for ‘dry socket’? (2) /// How would you manage this condition?

Answer 21

• Explain to patient the pain is not due to retained root, and warn existence of pain for a week or more
• Irrigation with socket with saline or antiseptic like CHX
• Place resorbable dressing inside socket, replace after 24 –48 hrs and multiple replacement is required(no healing if using non-resorbable dressing)
• Prescribe short-term analgesic

Question 22

Describe the cells of chronic inflammation (2005, 2) (2007, 2)

Answer 22

B cells
T cells
Plasma cells
Macrophages
Monocytes
Fibroblasts

Question 23

What are cytokines? List one pro-inflammatory and one anti-inflammatory cytokine.

Answer 23

Cytokines are proteins or glycoproteins involved in cellular communication.

They can enhance or inhibit a response.

Pro-inflammatory: interleukin – 1
Anti-inflammatory: interleukin - 10

Question 24

What is the major difference between healing by repair & regeneration (2 or 3)

Answer 24

Repair: replacement of damaged or destroyed tissue by living fibrous ct with a consequent loss of the
pre-existing normal tissue architecture

Regeneration: replacement damaged or destroyed tissue by living tissue of the same type as that which
was destroyed with consequent restoration of the pre existing normal tissue architecture