2: Response & Wound Healing

Question 1

what complications happen before/during procedure?

Answer 1

• vasovagal syncope (VVS)
• carotid sinus syndrome (CSS)
• situational syncope (not impt)

Question 2

after procedure, trauma alters _____

Answer 2

after procedure, trauma alters the metabolism of substrates and micronutrients

Question 3

after procedure, the body’s _____ changes, increasing the demand for _____

Answer 3

after procedure, the body’s hormonal situation changes, increasing the demand for energy, proteins and micronutrients

Question 4

what are the things involved in mediating response to trauma?

Answer 4

• endocrine system
• afferent neuronal impulses
• efferents
• endothelium
• acute inflammatory response

Question 5

[endocrine system elaboration in mediating response to trauma]
- pituitary gland increases __ and __
- adrenal gland increases __ and __
- pancreatic increases __, decreases __
- others __, __, decreases __ and __
- the net effect of the endocrine response to surgery is

Answer 5

• pituitary gland increases GH and ACTH
• adrenal gland increases cortisol and aldosterone
• pancreatic increases glucagon, decreases insulin
• others renin, angiotensin, decreases sex hormones and T4
• the net effect of the endocrine response to surgery is an increased secretion of catabolic hormones (break down)

Question 6

how do afferent neuronal impulses mediate response to trauma?

Answer 6

these impulses travel from the site of injury to hypothalamus

Question 7

[how do efferents mediate response to trauma]
- impulses go to _____ then ______
- causes increases in _____
- lead to _____ and _____

Answer 7

• impulses go to sympathetic nervous system then adrenal medulla
• causes increases in catecholamines
• lead to tachycardia and hypertension
• I love you

Question 8

[how does the endothelium mediate response to trauma]
- activated _____ and _____ produce _____ (_____)
- these act on _____ to produce _____

Answer 8

• activated leucocytes and fibroblasts produce cytokines (IL/INF)
• these act on target cells to produce different proteins

Question 9

[how does the acute inflammatory response mediate response to trauma]
- via _____
- _____ (___, ___ etc)
- consequence is the _____

Answer 9

• via cellular activation
• inflammatory mediators (TNF, IL1 etc)
• consequence is the mobilization of substrates

Question 10

• response to trauma can be divided into ___ phase and ___ phases
  [first phase] = occurs _____, lasts from __ to __ hours
  [second phase] = follows [first phase], onset is in ____
  after that there’s the ______ phase, followed by ______ phase

Answer 10

• response to trauma can be divided into ebb phase and flow phase
• ebb = occurs immediately after trauma, lasts from 24-48 hours
• flow = follows ebb phase, onset is in a few days
• after that there’s the anabolism phase, followed by the fatty replacement phase

Question 11

what are the flow of events under the ebb phase?
- like the body still _____ from the injury
- characterised by _____
- priority is to _____ / _____
- name 6x things that are decreased
- when these all decrease, _____ is reduced
- these mechanisms are associated with _____ (dont want the person to _____ so everything decreases)
- _____ drops
- reduction in _____ may be a protective mechanism during this period of _____

Answer 11

• like the body still in shock from the injury
• characterised by hypovolemic shock
• priority is to maintain life/ homeostasis
  
  • decrease cardiac output
  • decrease o2 consumption
  • decrease bp
  • decrease tissue perfusion
  • decrease body temp
  • decrease metab rate
• when these all decrease, tissue perfusion is reduced
• these mechanisms are associated with hemorrhage (dont want the person to lose too much blood so everything decreases)
• body temp drops
• reduction in metab rate may be a protective mechanisms during this period of hemodynamic instability

Question 12

what are the flow of events under the flow phase?
- involves _____, breaking down of _____
- name 5 things that have increased levels
- what are the 4 key catabolic elements of flow phase?
- _____
- alterations in _____
- alterations in _____
- ______
- the ______ will cause
- _____ break down to ______
- breakdown of _____ in liver and muscle to _____
- breakdown of muscle to _____
- __ is needed for _____ and synthesis of _____ involved in ______ and _____
- but this process leads to loss of _____, notably ______
- these are the ______
- if they are not present, the prolonged ______ without provision of adequate _____ and _____ leads to impaired _____ and ultimately ____
- _____ increases as the body mobilises _____

Answer 12

• flow = follows ebb phase, onset is in a few days
  
  • involves catabolism, breaking down of energy stores
  • increased levels of
    
    • catecholamines
    • glucocorticoids
    • glucagon
    • release of cytokines, lipid mediators
    • acute phase protein production
  • key catabolic elements of flow phase
    
    • hypermetabolism
    • alterations in skeletal muscle protein
    • alterations in liver proteins
    • insulin resistance
  • the endocrine response will cause
    
    • fatty deposits break down to fatty acids
    • breakdown of glycogen in liver and muscle to glucose
    • breakdown of muscle to aa
      
      • aa is needed for gluconeogenesis and synthesis of proteins involved in immunologic response and tissue repair
      • but this process leads to loss of body mass, notably body protein
    • these are the calorie sources
    • if they are not present, the prolonged metabolic stress without provision of adequate calories and proteins leads to impaired body functions and ultimately malnutrition
  • body temp increases as the body mobilises tissue energy reserves

Question 13

what are the different classifications of wounds?

Answer 13

• clean wound
• clean/ contaminated wound
• contaminated wound
• infected wound

Question 14

clean wounds are ______ wounds that follow ______ (____) trauma)

Answer 14

clean wounds are operative incisional wounds that follow non penetrating (blunt) trauma)

Question 15

clean/contaminated wounds are _____ wounds in which no ____ is encountered but the ____ tracts have been entered

Answer 15

clean/contaminated wounds are uninfected wounds in which no inflammation is encountered but the resp, GI, genital or urinary tract have been entered

Question 16

contaminated wounds are _____ wounds or ____ wounds involving a ____ in ____ technique that show evidence of ______

Answer 16

contaminated wounds are open , traumatic wounds or surgical wounds involving a major break in sterile technique that show evidence of inflammation

Question 17

infected wounds are _____ wounds containing ____ and wounds with evidence of a _____ eg ____

Answer 17

infected wounds are old, traumatic wounds containing dead tissue and wounds with evidence of a clinical infection eg purulent drainage

Question 18

[classifications of wound closure]
what are the characteristics of primary intention?
- all _____
- heals in ______
- no _______
- minimal ______

Answer 18

• all layers are closed
• heals in minimum amount of time
• no separation of wound edges
• minimal scar formation

Question 19

[classifications of wound closure]
what are the characteristics of secondary intention?
- deep layers are ___ but superficial layers ___
- in cases of infection, ___, ___ or imprecise ____
- wound edges ____
- ____ cant be _____
- extensive ______
- severe ______
- significant _______
- example is ______

Answer 19

• deep layers are closed but superficial layers left to heal from inside out
• in cases of infection, excessive trauma, tissue loss or imprecise approximation of tissue
• wound edges separated
• gap between them cant be bridged directly
• extensive loss of epithelium
• severe wound contamination
• significant subepithelial tissue damage
• example is exo socket

Question 20

what are the phases under the process of wound healing?

Answer 20

• inflammation
• proliferative phase
• maturation phase

Question 21

[elaboration] describe the flow of events during wound healing
- inflammation occurs when ____ release ___ that increase expression of _____ in ______
- _____, _____ and _____ cause vessel ____ (______)
- also cause decrease in ____, act as _____ for _____
- these are most abundant cells in ____ period
- after the _____ have removed _____, proliferative phase occurs next
- will release further ____ acting as _____ for _____
- _____ now migrate into the wound, secrete ______
- ______ occurs by __ hours
- secretion of ___, ____ and ____, and ______ continues for up to _____
- greatest increase in _____ occurs during this phase
- finally its maturation phase, starts from ____ week and continues for up to ___ months
- where ____ is converted to ____, _______ continues to increase up to __% of normal tissue

Answer 21

• inflammation occurs when damaged endothelial cells release cytokines that increase expression of integrands in circulating lymphocytes
  
  • idk wtf integrands are
• histamine, serotonin and kinins cause vessel contraction (thromboxane)
  
  • also cause decrease in blood loss, act as chemotactic factors for neutrophils
  • these are most abundant cells in initial 24 hour period
• after the neutrophils have removed cellular debri, proliferative phase occurs next
  
  • will release further cytokines acting as attracting agents for macrophages
  • fibroblasts now migrate into the wound, secrete collagen type III
  • angiogenesis occurs by 48 hours
  • secretion of collagen, macrophage remodeling and secretion, and angiogenesis continues for up to 3 weeks
  • greatest increase in wound strength occurs during this phase
• finally its maturation phase, starts from 3rd week and continues for up to 9-12 months
  
  • where collagen III is converted to collagen I, tensile strength continues to increase up to 80% of normal tissue

Question 22

what is the direction of healing?
- slowly from ____
- towards ____ by _____
- result in greater ____ than ____
- in time, ___ tends to ____
- result in _____

Answer 22

• slowly from bottom of wound
• towards the surface by granulation
• result in greater mass of scar tissue than healing by primary intention
• in time, scarring tends to shrink
• result in wound contracture

Question 23

[the stages following exo]
immediately:
- blood fills _____
- both ____ and ____ pathways of _____ are activated
- resultant _____ containing ____seals off ___ and ____ size of ____

Answer 23

[the stages following exo]
immediately:
- blood fills exo site
- both intrinsic and extrinsic pathways of clotting cascade are activated
- resultant fibrin meshwork containing entrapped red blood cells seals off torn blood vessels and reduces size of exo wound

Question 24

[the stages following exo]
first 24-48 hours
- _____ of the clot
- ____ and ___ of blood vessels within ____
- followed by _______
- formation of _______
- these hours are critical because _____ then ____ and be ____
- aka _____ (no more clot)

Answer 24

[the stages following exo]
first 24-48 hours
- organization of the clot
- engorgement and dilation of blood vessels within PDL remnants
- followed by leukocytic migration
- formation of fibrin layer
- these hours are critical because if the blood clot is disintegrated then healing may be greatly delayed and be extremely painful
- aka dry socket (no more clot)

Question 25

[the stages following exo]
first week
- clot forms a ____ upon which ____
- _____ at the _____ grows over the surface of the _____
- the _____ migrates and covers the ____
- ____ stage occurs where
- ___ enter ___ to remove ____ from the area, begin to break down ___ that are left in the ____
- _____ also begins here
- _____ of _____ and ______
- _____ down the ____ until it reaches a level at which it ________ or it _______over which it can migrate
- _______ is filled with numerous _____ and ______
- finally during the 1st week of healing, _______ accumulate along the _______

Answer 25

[the stages following exo]
first week
- clot forms a temporary scaffold upon which inflammatory cells migrate
- epithelium at the wound periphery grows over the surface of the organizing clot
- the peripheral gingival epithelium migrates and covers the bone
- inflammatory stage occurs where
- WBC enter socket to remove contaminating bacteria from the area, begin to break down any debri like bone fragments that are left in the socket
- fibroplasia also begins here
- ingrowth of fibroblasts and capillaries
- epithelial migration down the socket wall until it reaches a level at which it contacts epithelium from the other side of the socket or it encounters the bed of granulation tissue under the blood clot over which it can migrate
- granulation tissue is filled with numerous immature capillaries and fibroblasts
- finally during the 1st week of healing, osteoclasts accumulate along the crestal bone

Question 26

[the stages following exo]
second week
- ___ amount of ___ fills the socket
- ______ has begun along the ___lining the socket
- in ____ sockets, ___ may have become ____ by this point
- _____ slowly extend into the clot from the ____
- _______ of the ______ of the alveolar socket is more _____
- processes that begun during the second week continue during ____ , with _____ complete at this time

Answer 26

[the stages following exo]
second week
- large amount of granulation tissue fills the socket
- osteoid deposition has begun along the alveolar bone lining the socket
- in smaller sockets, epithelium may have become fully intact by this point
- trabeculae of osteoid slowly extend into the clot from the alveolus
- osteoclastic resorption of the cortical margin of the alveolar socket is more distinct
- processes that begun during the second week continue during the third and fourth weeks of healing, with epithelialization of most sockets complete at this time

Question 27

[the stages following exo]
third week
- __________ at this point
- ______ is filled with _____ and ______ forms at the _______
- surface of the wound is completely _____ with _____ scar formation
- ______ by ____ and _____ continues for several more weeks

Answer 27

[the stages following exo]
third week
- most of the wound would have healed at this point
- extraction socket is filled with granulation tissue and poorly calcified bone forms at the wound perimeter
- surface of the wound is completely reepithelialized with minimal or no scar formation
- active bone remodeling by deposition and resorption continues for several more weeks

Question 28

what are the histo aspects of healing?

Answer 28

• inflammatory: lasts 3-5 days
• proliferative: stimulated by the cytokines and growth factors secreted during the inflammatory phase
• remodeling

Question 29

[inflammatory histo aspect of healing]
- vasoconstriction of injured vasculature is the ________
- initiation occurs when _____ and ____ activate ____ (____ factor), which initiates various effectors of the _____ including:
[list 4x effectors]
- wound fills with ____, ______ and _____
- _______ then begins to migrate
- ______ begin to transform into _______
- also will have aggregation which is
- _____ (____) ____at the injury site, adhere to each other and the _______ to form a ____
- which is organized within a fibrin matrix
- the vasoconstriction is followed by vasodilation
- vasodilation is caused by actions of ____, ____ and other ______
- dilation causes intercellular gaps to occur, which allows _____ and ______
- the clot _____ and provides a ____ through which cells can migrate during the repair process
- the clot also serves as a reservoir of ____ and ______that are released as _______
- secreted proteins include: 4x

Answer 29

[inflammatory histo aspect of healing]
- vasoconstriction of injured vasculature is the spontaneous tissue reaction to bleeding
- initiation occurs when tissue trauma and local bleeding activate factor XII (hageman factor), which initiates various effectors of the healing cascade including:
- complement
- plasminogen
- kinin
- clotting systems
- wound fills with clotted blood, inflammatory cells and plasma
- adjacent epithelium then begins to migrate
- undifferentiated mesenchymal cells begin to transform into fibroblasts
- also will have aggregation which is
- circulating platelets (thrombocytes) rapidly aggregate at the injury site, adhere to each other and the exposed vascular subendothelial collage n to form a primary platelet plug
- which is organized within a fibrin matrix
- the vasoconstriction is followed by vasodilation
- vasodilation is caused by actions of histamine, prostaglandins and other vasodilatory substances
- dilation causes intercellular gaps to occur, which allows egress of plasma and emigration of wbc
- the clot secures hemostasis and provides a provisional matrix through which cells can migrate during the repair process
- the clot also serves as a reservoir of cytokines and growth factors that are released as activated platelets degranulate
- secreted proteins include
- interleukins
- TGF B
- PDGF
- VEGF

Question 30

[proliferative histo aspect of healing]
- start as early as _____ and last up to _____
- distinguished by _____ aka ______
- an essential first step is the ______ to supply ______ necessary for the ________
- ____ increases ______ , _____ are haphazardly laid down by _____, _____ begin to establish contact with _____ from other sites in wound

Answer 30

[proliferative histo aspect of healing]
- start as early as 3rd day post injury and last up to 3 weeks
- distinguished by formation of pink granular tissue aka granulation tissue
- an essential first step is the establishment of local microcirculation to supply oxygen and nutrients necessary for the elevated metabolic needs of regenerating tissues
- proliferation increases epithelial thickness, collagen fibers are haphazardly laid down by fibroblasts, budding capillaries begin to establish contact with their counterparts from other sites in wound

Question 31

[remodeling histo aspect of healing]
- can last for ______ and involves a finely choreographed balance between ____ and ____
- as ______ of the healing wound decrease, ______ begins to regress
- _____ start to disappear and ____ deposited during _____ (aka _____ phase) is gradually replaced by stronger _______
- _______ is restored, _____ is remodeled into ______, _____ slowly disappear and _____ is reestablished

Answer 31

[remodeling histo aspect of healing]
- can last for several years and involves a finely choreographed balance between matrix degradation and formation
- as metabolic demands of the healing wound decrease, rich network of capillaries begins to regress
- fibroblasts start to disappear and collagen type 3 deposited during granulation phase (aka proliferative phase) is gradually replaced by stronger type 1 collagen
- epithelial stratification is restored, collagen is remodeled into more efficiently organized patterns, fibroblasts slowly disappear and vascular integrity is reestablished

Question 32

[local factors affecting healing]
what are the factors? (8 points)

Answer 32

[local factors affecting healing]
- wound sepsis (infection)
- location
- poor blood supply
- wound tension (amount of tension needed to approximate wound edges, sum of the closing tensions for both flaps)
- foreign bodies (eg if amalgam comes out during exo)
- previous irradiation
- poor technique (instead of tearing PDL, we crush the bone)
- immobilization so that formation of connective tissue is not hindered

Question 33

[systemic factors affecting healing]
what are the factors? (4 points)

Answer 33

[systemic factors affecting healing]
- systemic diseases (most common is diabetes)
- nutritional deficiencies - proteins, vitamins
- therapeutic agents
- age - wounds in younger persons heal more rapidly

Question 34

what are the complications in healing?
5 points

Answer 34

[complications in healing]
- localized alveolar osteitis (dry socket)
- fibrous healing of extraction wound
- delay in the presence of systemic disease
- apposition of regenerate bone to remaining alveolar bone takes place at slower rate
- infected socket remains open or partially covered with hyperplastic epithelium for extended periods

Question 35

[complications in healing]
localized alveolar osteitis (dry socket):
- manifests clinically, can be:
- ______ involving either the whole or part of the ______ socket (______)
- ______ (with evidence of ____ or got _____ within it)
- ______ may be evident, confirmed by ______ and ______
- painful
- arises _____ after extraction, may last for ____
- overall incidence is _%
- more common in ____ areas like ____
- predisposing factors for dry socket
- 7x points

Answer 35

[complications in healing]
localized alveolar osteitis (dry socket):
- manifests clinically, can be:
- inflammation involving either the whole or part of the condensed bone lining the tooth socket (lamina dura)
- empty socket (with evidence of broken down blood clot or got food debris within it)
- intense odor may be evident, confirmed by dipping cotton wool into socket and pass under nose
- painful
- arises 24-72 hours after extraction, may last for 7-10 days
- overall incidence is 3%
- more common in less vascular areas like mandibular bone
- predisposing factors for dry socket
- infection
- extraction trauma
- poor blood supply
- site (mandi more common as bone is denser, posterior molar is slightly less vascular)
- smoking
- females more common, especially those on oral contraceptives
- systemic factors eg oral contraceptives

Question 36

[complications in healing]
fibrous healing of extraction wound:
- is _____, usually follows _____
- commonly occurs when extraction is accompanied by ______ along with ______
- presents as a _______ area in site of previous extraction
- tx = __________

Answer 36

[complications in healing]
fibrous healing of extraction wound:
- is uncommon, usually follows complicated or surgical extraction
- commonly occurs when extraction is accompanied by loss of both lingual and buccal plates along with periosteum
- presents as a well circumscribed radiolucent area in site of previous extraction
- tx = excision of lesion

Question 37

[complications in healing]
delay in the presence of systemic disease:
- such as ______ or _______

Answer 37

[complications in healing]
delay in the presence of systemic disease:
- such as diabetes or osteoporosis

Question 38

[radiographic stuff after exo]
- ____ initiates same sequence of ____, ____, ______ and _____ seen in _____ or ____
- remaining empty socket consists of _____ (with ______) covered by ____, with a rim of _____ (____) left at the _____ portion
- socket fills with ___, ___ and seals socket from _____
- _____ continues to be ____ from ____ and ____of socket
- new _____ laid down across the socket
- ______ later, _____ lining a socket is fully resorbed. this is recognized radiographically as a ________
- as ____ fills the socket, ____ moves toward the ___ , eventually becomes level with _____
- radiographic evidence of bone formation only becomes apparent ______ after
- visible remnant of the socket after ___ is the _____ that remains on _____

Answer 38

[radiographic stuff after exo]
- removal of tooth initiates same sequence of inflammation, epithelialization, fibroplasia and remodeling seen in prototypic skin or mucosal wounds
- remaining empty socket consists of cortical bone (with radiographic lamina dura) covered by torn PDL, with a rim of oral epithelium (gingiva) left at the coronal portion
- socket fills with blood, coagulates and seals socket from oral environment
- cortical bone cntinues to be resorbed from crest and walls of socket
- new trabecular bone laid down across the socket
- 4-6 months later, cortical bone lining a socket is fully resorbed. this is recognized radiographically as a loss of lamina dura
- as bone fills the socket, epithelium moves toward the crest, eventually becomes level with adjacent crestal gingiva
- radiographic evidence of bone formation only becomes apparent 6-8 weeks after
- visible remnant of the socket after 1 year is the rim of fibrous scar tissue that remains on edentulous alveolar ridge

Question 39

[bone grafting - how does bone heal?]
- ost____________
- presence of ____/ ____in graft with ____ and formation of ____ and ______
- eg in the case of _____ where the px ____ is collected ____ then returned to them after
- ost____________
- ____ material “conduct” path for ____ to ______ and _____ from ____ to form _____
- ____ eat away the ____ then _____secrete
- ost____________
- _____ of bone induces ______ from ____ (__)
- all grafts must be __________, if there are ________, _______ will be disrupted

Answer 39

[bone grafting - how does bone heal?]
- osteogenic
- presence of viable osteoblasts/ cytes in graft with direct healing and formation of new bone and blood vessels
- eg in the case of autogenous marrow where the px stem cell is collected before the procedure then returned to them after
- osteoconductive
- bone inorganic material “conduct” path for osteoclasts to resorb HAP crystal and osteoblasts from host bed to form new osteons
- osteoclasts eat away the periphery then osteoblasts secrete
- osteoinductive
- organic portion of bone induces formation of new osteoblasts from osteoprogenitor cells (BMP)
- all grafts must be fixated in place, if there are micromotions, angiogenesis will be disrupted/

Question 40

what are the types of bone graft?
4x types

Answer 40

what are the types of bone graft?
- autogenous
- allogenous - human
- xenogenous - bovine
- alloplastic beta tricalcium phosphate

Question 41

[traditional concept of bone healing in a fracture]
- ______ ______ to _____
- ______ followed by _____ and _______
- ________ and ______ of _________
- _______ __________
- ______ from _____ ______and form _____ to _____ between _____, leading to __________
- _______ forms beneath ______
- _____ eventually replaced by _____ through ______________
- ________ of ________
- until _________formed in previous fracture
- _________
- extends into _______ when ________exist
- if movement occurs, only _______bridges the gap
- if no ________, ________ forms to _______
- ___ ______(persistent ______, ______/ ____________and ________)
- occurs if there is ______ between _______, ___________, _________and ________________

Answer 41

• immediate response to injury
  
  • acute inflammation followed by migration of vessels and osteogenic cells
  • fibrovascular invasion and organization of haematoma
• callus formation
  
  • osteogenic cells from periosteum proliferate and form thin rim of bone to bridge gap between fragments, leading to fusiform swelling
  • hyaline cartilage forms beneath rim of bone
  • callus eventually replaced by woven bone through endochondral ossification
• remodeling of woven bone
  
  • until compact lamellar bone formed in previous fracture
• osteogenesis
  
  • extends into fracture gap when stable conditions exist
  • if movement occurs, only fibrous tissue bridges the gap
  • if no satisfactory immobilization, exuberant callus forms to stabilize fragments
• non union (persistent fracture gap, fibrous/ fibro cartilaginous bridging and pseudoarthrosis)
  
  • occurs if there is a large gap between fragments, persistent movement, avascular necrosis and interposed soft tissue

Question 42

[types of bone healing]
primary bone healing:
- occurs when _______,______
- _______ at _____site leads to ______, ______, ______ and ________
- depends on __________ and _________
- divided into _______ and ______/_____ healing

• ________ healing
  
  • if the surgery can ______, ______ and _______ to ______ the ________
  • local _______ cross ______
    
    • _______ forms, existing ones ______ until there is _______ with _______ and _______
  • _______ form ______ in __ weeks
• _____/______ healing
  
  • when bone is in _____
  • begins with __________of _______on either side of fracture
  • there is ______ in ________that is some distance from injury
  • ___________ towards site, ______ towards and across fracture
    
    • __ mm in ______ days, by _____ and ______ 19__
  • ________ in _________
  • __________ that matures directly into _______
  • wider gaps bridged by _______
  • _________ occurs by __ weeks, completed by __ weeks
  • _________ by _____ weeks due to ______

Answer 42

[types of bone healing]
primary bone healing:
- occurs when fragments are stable, interfragmentary surfaces well aligned
- compression at fracture site leads to bone adaptation, frictional stability, direct cortical bone to bone contact and osteoinduction
- depends on size of fracture gap and stability
- divided into cancellous bone and cortical bone/ contact healing

• cancellous bone healing
  
  • if the surgery can align bony trabeculae anatomically, capillaries proliferate and traverse the gap to reconstitute the torn medullary network
  • local osteogenic cells cross fracture site
    
    • new trabeculae forms, existing ones thickens with woven bone until there is clinical union with little fibrosis and no cartilage precursors
  • closely adapted cancellous surfaces form clinical union in 4 weeks
• cortical bone/ contact healing
  
  • when bone is in direct cortical contact
  • begins with osteoclastic widening of haversian canals on either side of fracture
  • there is initial healing in viable bone that is some distance from injury
  • widened canals oriented longitudianlly towards site, osteoclasts excavating towards and across fracture
    
    • 1 mm in 13-20 days, by Schenk and Willeneger 1967
  • capillary in growth
  • osteoblasts line tunnels laying down osteoid that matures directly into lamellar bone
  • wider gaps bridged by woven bone
  • cortical bridging occurs by 8 weeks, completed by 16 weeks
  • clinical union by 6-8 weeks due to cancellous healing

Question 43

[types of bone healing]
gap healing:
- _______only works for distances up to ___
- ______ heal by _________ with __________ by _________, ____ to ______, ______ to ________
- _________ to become parallel to _________

we must treat based on the type of injury:
- if its a ______ fracture, splinting for _______ wont be sufficient, need _____
- if it is an ________ with ________ but bone is okay, _____ splint is sufficient. if we splint for _______ we will get _______

Answer 43

[types of bone healing]
gap healing:
- primary healing only works for distances up to 20 micro metres
- larger gaps heal by gap healing with deposition directly by new lamellar bone, parallel to fracture, transverse to long axis of bone
- eventual remodeling to become parallel to long axis of bone

we must treat based on the type of injury:
- if its a dental alveolar fracture, splinting for 14 days wont be sufficient, need 1 month
- if it is an injured PDL with avulsed tooth but bone is okay, 10-14 days splint is sufficient. if we splint for 1 month we will get ankylosis

Question 44

[nerve healing]
intro of nerve anatomy:

- peripheral nerves got
    - \_\_\_\_\_
    - \_\_\_\_ \_\_\_\_ --> \_\_\_\_\_, \_\_\_\_\_\_, \_\_\_\_\_\_
    -\_\_\_\_\_\_\_\_ - \_\_\_\_\_\_\_\_and un\_\_\_\_\_\_\_\_\_fibres
    - \_\_\_\_\_\_\_, is a \_\_\_\_\_ complex that \_\_\_\_\_\_ and \_\_\_\_\_\_\_ conduction rate
        - \_\_\_\_\_\_\_\_\_ are separated by \_\_\_\_\_\_, where \_\_\_\_\_\_\_ are bare
        - impulses jump from one node to the next via \_\_\_\_\_\_\_\_\_

Answer 44

[nerve healing]
intro of nerve anatomy:

- peripheral nerves got
    - axon
    - connective tissue --> endoneurium, perineurium, epineurium
    - nerve trunks - myelinated and unmyelinated fibres
    - myelin, is a protein lipid complex that insulates and increases conduction rate
        - myelinated nodes are separated by nodes of Ranvier, where axons are bare
        - impulses jump from one node to the next via saltatory conduction

Question 45

[nerve healing]
pathological processes:

- \_\_\_\_\_\_ \_\_\_\_\_\_\_\_
    - patient will be \_\_\_\_, takes weeks or months to recover
    - is \_\_\_\_\_\_\_, following \_\_\_\_\_ or \_\_\_\_\_\_
    - degeneration of \_\_\_\_\_\_\_
    - occurs within \_\_\_\_\_\_ of injury
    - nerve will be \_\_\_\_\_\_\_\_\_\_
    - there will be sensation of \_\_\_\_\_\_\_\_ or \_\_\_\_\_\_\_\_ during recovery which is good because \_\_\_\_\_\_\_\_
- \_\_\_\_ \_\_\_\_\_\_\_
    - \_\_\_\_\_\_\_\_\_\_ is \_\_\_\_\_\_\_\_\_\_\_
    - regeneration can occur since \_\_\_\_\_\_\_ of \_\_\_\_\_\_\_\_\_ survives and act as a \_\_\_\_\_\_\_\_ along which the axon \_\_\_\_ up to a rate of about \_\_\_\_ per day
    - if \_\_\_\_\_\_\_ is intact, it will sprout \_\_\_\_\_\_
- \_\_\_\_\_\_\_\_
    - \_\_\_\_\_\_\_\_ of \_\_\_\_\_\_\_\_ occurs without \_\_\_\_\_\_\_\_\_
    - \_\_\_\_\_\_\_\_\_\_ affects \_\_\_\_\_\_\_, causes \_\_\_\_\_\_\_\_\_\_\_\_\_\_ or \_\_\_\_\_\_\_\_\_\_
    - \_\_\_\_\_\_\_\_\_\_\_ is caused by \_\_\_\_\_\_ eg \_\_\_\_\_\_\_\_ syndrome

Answer 45

[nerve healing]
pathological processes:

- wallerian degeneration
    - patient will be numb, takes weeks or months to recover
    - is distal axon degeneration, following section or severe injury
    - degeneration of myelin
    - occurs within 7-10 days of injury
    - nerve will be inexcitable electrically
    - there will be sensation of pins and needles or ants crawling on lips during recovery which is good because axons are trying to grow
- axon degeneration
    - distal degenerated nerve is inexcitable electrically
    - regeneration can occur since basement membrane of schwann cell survives and act as a skeleton along which the axon regrows up to a rate of about 1mm per day
    - if nerve sheath is intact, it will sprout axons into tubule
- demyelination
    - segmental destruction of myelin sheath occurs without axon damage
    - primary lesion affects schwann cells, causes marked slowing of conduction or conduction block
    - local demyelination is caused by inflammation eg Guillain Barre syndrome

Question 46

[nerve healing]
types of nerve injuries (Seddon’s classification):

- \_\_\_\_\_\_\_\_\_
    - reversible \_\_\_\_\_\_\_\_\_\_\_\_, loss of \_\_\_\_\_\_\_\_
    - due to \_\_\_\_\_\_\_\_\_\_ causing \_\_\_\_\_\_\_\_\_\_\_
- \_\_\_\_\_\_\_\_ - part of nerve injured
    - rapid \_\_\_\_\_\_\_\_\_
    - \_\_\_\_\_\_\_\_\_\_\_ destroyed
- \_\_\_\_\_\_ - no more \_\_\_\_\_
    - \_\_\_\_\_\_ of \_\_\_\_\_\_, may occur in \_\_\_\_\_\_
    - if injury is more severe, whether \_\_\_\_\_\_\_ or not, recovery will not occur

Answer 46

[nerve healing]
types of nerve injuries (Seddon’s classification):

- neurapraxia
    - reversible physiological nerve conduction block, loss of some types of sensation
    - due to mechanical pressure causing segmental demyelination
- axonotmesis - part of nerve injured
    - rapid wallerian degen
    - endoneurial tubules destroyed
- neurotmesis - no more nerve
    - division of nerve trunk, may occur in open wound
    - if injury is more severe, whether nerve is in continuity or not, recovery will not occur

Question 47

[nerve healing]
types of nerve injuries (Sunderland’s classification):

- first degree injury
    - 3x points
- second degree
    - corresponds to \_\_\_\_\_\_\_\_\_\_\_\_
    - \_\_\_\_\_\_\_ takes place
    - \_\_\_\_\_\_\_\_is preserved so \_\_\_\_\_\_\_\_ can lead to near complete recovery without \_\_\_\_\_
- third degree
    - worse than \_\_\_\_\_\_\_\_
    - \_\_\_\_\_\_\_\_\_\_ but \_\_\_\_\_\_\_\_ intact, internal damage limited
    - chances of \_\_\_\_\_\_\_\_\_\_ are good but \_\_\_\_ and \_\_\_\_\_ will limit recovery

Answer 47

[nerve healing]
types of nerve injuries (Sunderland’s classification):

- first degree injury
    - transient ischemia
    - neurapraxia
    - reversible stuff
- second degree
    - corresponds to Seddon’s axonotmesis
    - axonal degen takes place
    - endoneurium is preserved so regeneration can lead to near complete recovery without intervention
- third degree
    - worse than axonotmesis
    - endoneurium disrupted but perineural sheaths intact, internal damage limited
    - chances of axons reaching targets are good but fibrosis and crossed connections will limit recovery