2: Response & Wound Healing Flashcards
what complications happen before/during procedure?
- vasovagal syncope (VVS)
- carotid sinus syndrome (CSS)
- situational syncope (not impt)
after procedure, trauma alters _____
after procedure, trauma alters the metabolism of substrates and micronutrients
after procedure, the body’s _____ changes, increasing the demand for _____
after procedure, the body’s hormonal situation changes, increasing the demand for energy, proteins and micronutrients
what are the things involved in mediating response to trauma?
- endocrine system
- afferent neuronal impulses
- efferents
- endothelium
- acute inflammatory response
[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
- 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)
how do afferent neuronal impulses mediate response to trauma?
these impulses travel from the site of injury to hypothalamus
[how do efferents mediate response to trauma]
- impulses go to _____ then ______
- causes increases in _____
- lead to _____ and _____
- impulses go to sympathetic nervous system then adrenal medulla
- causes increases in catecholamines
- lead to tachycardia and hypertension
- I love you
[how does the endothelium mediate response to trauma]
- activated _____ and _____ produce _____ (_____)
- these act on _____ to produce _____
- activated leucocytes and fibroblasts produce cytokines (IL/INF)
- these act on target cells to produce different proteins
[how does the acute inflammatory response mediate response to trauma]
- via _____
- _____ (___, ___ etc)
- consequence is the _____
- via cellular activation
- inflammatory mediators (TNF, IL1 etc)
- consequence is the mobilization of substrates
- 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
- 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
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 _____
- 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
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 _____
- 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
what are the different classifications of wounds?
- clean wound
- clean/ contaminated wound
- contaminated wound
- infected wound
clean wounds are ______ wounds that follow ______ (____) trauma)
clean wounds are operative incisional wounds that follow non penetrating (blunt) trauma)
clean/contaminated wounds are _____ wounds in which no ____ is encountered but the ____ tracts have been entered
clean/contaminated wounds are uninfected wounds in which no inflammation is encountered but the resp, GI, genital or urinary tract have been entered
contaminated wounds are _____ wounds or ____ wounds involving a ____ in ____ technique that show evidence of ______
contaminated wounds are open , traumatic wounds or surgical wounds involving a major break in sterile technique that show evidence of inflammation
infected wounds are _____ wounds containing ____ and wounds with evidence of a _____ eg ____
infected wounds are old, traumatic wounds containing dead tissue and wounds with evidence of a clinical infection eg purulent drainage
[classifications of wound closure]
what are the characteristics of primary intention?
- all _____
- heals in ______
- no _______
- minimal ______
- all layers are closed
- heals in minimum amount of time
- no separation of wound edges
- minimal scar formation
[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 ______
- 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
what are the phases under the process of wound healing?
- inflammation
- proliferative phase
- maturation phase
[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
- 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
what is the direction of healing?
- slowly from ____
- towards ____ by _____
- result in greater ____ than ____
- in time, ___ tends to ____
- result in _____
- 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
[the stages following exo]
immediately:
- blood fills _____
- both ____ and ____ pathways of _____ are activated
- resultant _____ containing ____seals off ___ and ____ size of ____
[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
[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)
[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)
[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 _______
[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
[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
[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
[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
[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
what are the histo aspects of healing?
- inflammatory: lasts 3-5 days
- proliferative: stimulated by the cytokines and growth factors secreted during the inflammatory phase
- remodeling
[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
[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
[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
[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
[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
[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
[local factors affecting healing]
what are the factors? (8 points)
[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
[systemic factors affecting healing]
what are the factors? (4 points)
[systemic factors affecting healing]
- systemic diseases (most common is diabetes)
- nutritional deficiencies - proteins, vitamins
- therapeutic agents
- age - wounds in younger persons heal more rapidly
what are the complications in healing?
5 points
[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
[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
[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
[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 = __________
[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
[complications in healing]
delay in the presence of systemic disease:
- such as ______ or _______
[complications in healing]
delay in the presence of systemic disease:
- such as diabetes or osteoporosis
[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 _____
[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
[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
[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/
what are the types of bone graft?
4x types
what are the types of bone graft?
- autogenous
- allogenous - human
- xenogenous - bovine
- alloplastic beta tricalcium phosphate
[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 ________________
- 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
[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 ______
[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
[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 _______
[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
[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 \_\_\_\_\_\_\_\_\_
[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
[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
[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
[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
[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
[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
[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
