2. WOUND
A break in the continuity of the
tissues

3.  Physical
 Compromisaed blood flow
 Crushing
 Desiccation
 Incision
 Irraiation
 Overcooling
 Overheating
CAUSES OF TISSUE
DAMAGE
 Chemical
 Agents wd inphysiologic pH
 Agents wd unphysiologic tonicity
 Proteases
 Vasoconstrictors
 Thrombogenic agents

4. WOUND REPAIR
EPITHELIALIZATION
 Injured epithelium has genetically programmed regenerative ability that allows it
to establish its integrity
 Free edges of epith cont. to migrate until it comes into contact with another free
edge of epith
 Abrasions (surface epith)

5. e.g
 detrimental effect of process of c.inhibition controlling
epithelialization occurs when
o Opening is accidently made into maxillary sinus during tooth
xtraction.
o If epith of sinus wall and oral mucosa is injured ..it begins to
proliferate in both areas….. creating OROANTRAL
FISTULA

6. STAGES OF WOUND
HEALING
TREE BASIC STAGES:
 INFLAMMATORY STAGE (reactive phase)
 PROLIFREATIVE STAGE (regenarative or reparative)
fibroplastic phase
 REMODELLING STAGE (maturational phase)

7. INFLAMMATOY STAGE
o Tissue injury…lasts for 3-5 days
o TWO PHASES:
i. Vascular phase
ii. Cellular phase

8. VASCULAR PHASE
initial vasoconstriction of disrupted vessels…..blood coagulation
Histamine , prostaglandins elaborate by WBCs
…vasodilation…which allows plasma to leak and leukocytes to
migrate into interstitial tissues

9.  Fibrin from plasma causes lymphatic obstruction ..accumulate in the
area of injury ….EDEMA

10. Signs of inflammation are
Redness
Swelling
Warmth and pain
Functio laesa
(fig)

11. CELLULAR PHASE
 Triggered by complement products .... act as chemotactic factors and cause
neutrophils…
o Margination ….
o Diapedesis
o Contact wd foreign material …. Degranulation
o Lysosomal enzymes …destroy foreign materials ..digest necrotic tissue also
aided by monocytes..macrophages

12.  Wd time lymphocytes accumulate at site of tissue injury
 B lymphocytes
o able to recognise antigenic material produce antibodies that assist
in identifying foreign materials and interact wd complements to lyse
foreign cells
 T lymphocytes
o Helper T cells
o Suppressor T cells
o Cytotoxic T cells

13.  LAG phase
 During ds phase no significant gain in wound strength occurs ..little
collegen deposition
 Fibrin … material holding wound…..little tensile strength

14. PROLIFATIVE STAGE
The combined process of epithelialization , firoplasia and
angiogenesis accur in ordr to replace dead
and missing tissue
Lasts for 2 days to 3 weeks

15. FIBROPLASTIC PHASE
 Strands of fibrin… form latticework…fibroblast can begin laying down ground
substance and tropocollagen
 Ground substance (mucopolysaccharides )…. Cement collagen fibers
 Fibroblasts secrete fibronectin…helps
 Stabilize fibrin
 Assist in recognizing foreign material
 Act as chemotactic factor for fibroblasts
 Helps to guide macrophages along fibrin strands for phagocytosis
of fibrin

16. Fibroblasts deposit tropocollagen….
Collagen produced in xcessive amounts nd laid down in
haphazard manner …. Effectiveness of collagen to
produce wound strength….rapidly inc during fibroplastic
stage , which normally lasts for 2-3 weeks.

17. If Wound is placed under tension
o at the beginning of fibroplasia
o Near the end of fibroplasia
o At the end of fibroplastic
stage……stiff…..erythematous…able
to wdstand 70-80% tension

18. REMODELLING STAGE
 Final stage….many of previous randomly laid collagen fibers are
destroyed as they are replaced by new collagen fibers, which are oriented to
better resist tensile forces of wound
 Slowly wound strength ..80-85%
 Allows the Scar to soften…
 Loss of edema…

19.  Wd time … vascularity
…diminishes wound
erythema….Elastin is not replaced in
injured tissue…. loss of flexibility along
scarred area(fig5)
 Take 3 weeks to 2 years to complete

20. WOUND CONTRACTION
o Final process….
o edges of wound migrate toward eachothr
o In which edges are not placed in apposition
, wound contracrion diminishes size of wound
 Problems
 third-degree …develop deforming nd debilitating contractures, if
wounds are not replaced wd skin grafts
 Can b lessened by placement of a layer of epith between d free edges
of wound

22. FACTORS THAT IMPAIR
WOUND HEALING
 Foreign mateial
3 basic problems
i. Bacteria…..
ii. Nonbacterial foreign material…
iii. Foeign material is often antigenic…
That decreases fibroplasia
 Infection

23.  Necrotic tissue
causes 2 problems
i. serve as a barrier to ingrowth of reparative cells….
ii. Serves as a protected niche for bacteria….
Include blood…..haematoma…….
 Drugs
 Nutritional problems
 Low temp
Distal aspect of xtremities (reduction of 1-1.5 C 2-3F)

24. Ischemia
 Dec blood supply >>> tissue necrosis >>> lessen the delivery to
wound of antibodies, WBCs >>> inc the chances of wound infection
 dec delivery of O2 ….nutrients….
 Caused by
 Tight or incorrectly located sutures, improperly designed flaps, excessive
external or internal pressure on wound, systemic hypotension,
peripheral vascular disease and anaemia

25. Tension
 If sutures are used to pull tissues together forcefully, >>> ischemia of
tissues
 If sutures are removed too early >>> reopen >>> heal with
scar…w-contraction
 If sutures are left in too long in attempt to overcome wound
tension…spread open during remodelling stage…and tract into epith
through which sutures ran will epithelialize and leave permanent
disfiguring marks

26.  Edges of wound in which no
tissue loss are placed
 Wound in which edges are
closely reapproximated
 Healing occur more rapidly wd
low risk of infection
 wound repair wd minimum
scar tissue
 Tissue loss has occurred so A
gap is left between edges of incision
or laceration
 Tissue loss prevents
approximation of wound edges
 Healing is slower
 Produces more scar formation
HEALING
Primary Intention 2ndy Intention

27.  Wound repair lessen amount of
re-epithelialization , collagen
deposition, contraction and remodelling
 Primary closure should b
performed in 6-8 hr of trauma
but vascular areas may b closed
upto 24 hrs
 e.g
Well repaired lacerations or
incisions, well-reduced bone fracture
 A large amount of epithelial
migration, collagen deposition,
contraction and remodelling
 Wound is left open and heals by
formation of granulation tissue and
contraction
 e.g
Extraction sockets, poorly
reduced fractures, deep ulcers, large
avulsive injuries of any soft tissue
Primay Intention 2ndy Intention

28. HEALING BY
THIRD INTENTION
 Delayed closure of wound after a vaiable period of time for which it
been left open
 Healing of wounds through the use of tissue grafts to cover large
wounds and bridge the gap between wound edges

29. THANK
YOU

30. ANY
QUESTION
?


31. OK
NOW UR QUIZ 
R U READY FOR THIS?
?????

32.  Causes of tissue damage
 Enumerate Stages of healing wd time
 Factors that impair wound healing