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What are the body's responses to injury?
- Inflammation
- Immunity
- Repair
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Injury
An alteration in the environment that causes tissue damage or necrosis.
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Necrosis
The pathologic death of one or more cells or a part of tissue, or an organ that results from irreversible damage to cells.
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Removal of foreign substances
Flushing action of tears, saliva, urine, and diarrhea
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Antibacterial activity
Enzymes in saliva and tears
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Mechanical defense
Respiratory system’s cilia and mucus
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____injury can affect teeth, soft tissue and bone.
physical
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___ injury can occur from the application of caustic substances.
chemical
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____ can cause injury by invading orofacial tissue and causing infections.
microorganisms
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_____ can render orofacial tissue more susceptible to injury from other sources, and toxic overdoses of some nutrients can also cause tissue damage.
nutritional deficiencies
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Innate (natural)defenses
are present from birth and include intact skin or mucosa that acts as a physical barrier to injury. The process of inflammation an its white blood cells that are brought to the area of injury are innate responses to injury.
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clinical signs (cardinal signs) of inflammation include: localized
redness, heat, swelling, pain and loss of the usual level of tissue function
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Inflammation
- suffix -itis
- Allows the body to eliminate injurious agents, contain injuries, and heal defects
- A nonspecific response to injury that involves the microcirculation and its blood cells.
- Extent and duration of the injury determine the extent and duration of inflammatory response.
- local or systemic
- acute or chronic
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Local
A disease process that is confined to a limited location in the body that is not general or systemic
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systemic
- Pertaining to or affecting the body as a whole, as well as a disease process pertaining to or affecting the body as a whole.
- Signs:
- Fever
- Leukocytosis
- Elevated C-reactive protein (CRP)
- Lymphadenopathy
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acute
An injury or course of inflammation that is of sort duration.
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chronic
- An injury or course of inflammation that is of long duration.
- Caused by persistent injuries
- Repair cannot be completed until source of injury is removed
- Cells involved:
- Macrophages
- Lymphocytes
- Plasma cells
- Neutrophils
- Monocytes
- Fibroblasts
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Inflammation: Sequence of Microscopic Events
- Injury to tissue
- Constriction of microcirculation
- Dilation of microcirculation → hyperemia → erythema and heat
- Increase in permeability
- Exudate leaves microcirculation → transudate
- Increased blood viscosity
- Decreased blood flow
- Margination and pavementing of white blood cells (WBCs) → chemotaxis
- WBCs enter tissue → emigration → exudate and edema
- WBCs ingest foreign material → phagocytosis
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microscopic events of inflammation
- they involve the small blood vessels or microcirculation.
- Can occur during acute and chronic inflammation
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Factors Affecting Amount of Scar Tissue
- Heredity
- Strength and flexibility needed in the tissue
- Tissue type
- Type of repair
- Healing by primary intention
- Healing by secondary intention
- Healing by tertiary intention
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Types of repair:
Healing by primary intention
- Healing of an injury in which there is little loss of tissue
- The margins are close together and very little granulation tissue forms
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Types of repair:
Healing by secondary intention
- The edges of the injury cannot be joined during healing
- A large clot forms, resulting in increased granulation tissue
- May result in excess scar tissue: A keloid
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Types of repair:
Healing by tertiary intention
- Delaying surgical tissue repair until infection is resolved
- An injured area may become infected, especially with puncture wounds
- In some situations, an infected injury is left open until infection is controlled
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microcirculation
The small blood vessels, including arterioles, capillaries, and venues of the vascular system.
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Biochemicals mediators
- chemicals in the body that activate responses
- May be derived from:
- Blood
- Endothelial cells
- White blood cells and platelets
- Pathogenic organisms as they injure the tissue
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Hyperemia
- An excess of blood within blood vessels in a part of the body.
- Local clinical signs of inflammation are erythema and heat.
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Erythema
redeness of skin or mucosa.
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Transudate
Extravascular fluid component of blood that passes through the endothelial cell walls of the microcirculation.
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margination
process during inflammation in which white blood cells tend to move to the periphery of the blood vessel at the site of injury.
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pavementing
The adherence of white blood cells to blood vessel walls during inflammation.
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emigration
The passage of white blood cells through the walls of small blood vessels and into injured tissue.
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exudate
A body fluid with a high protein content that leaves the microcirculation during an inflammatory response that consist of serum that contains white blood cells, fibrin and other protein molecules.
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edema
Excess level of plasma or exudate in the interstitial space that results in tissue swelling.
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serous exudate
An exudate that has a watery consistency. The consistency resembles that of serum.
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purulent exudate
An exudate containing pus or forming pus.
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abscess
A collection of purulent exudate that has accumulated in a contained space formed by the surrounding tissue.
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fistula
An abnormal passage that leads from an abscess to the body surface.
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chemotaxis
The movement of white blood cells as directed by biochemical mediators to an area of injury.
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phagocytosis
The ingestion and digestion of particulate material by cells.
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white blood cells
The cells within the blood and surrounding tissue, also called leukocytes , that are involved in the inflammatory immune responses.
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neutrophils
- The first white blood cell to arrive at a site of injury. primary cell involved in acute inflammation also called "polymorphonuclear leukocyte".
- constitute of 60%to 70%
- produced throughout life
- mobile cells
- function is phagocytosis of substances
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Two types of white blood cells involved in the inflammatory response are
neutrophils and monocytes (macrophages)
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Kinin System
- Active in early phases of inflammation
- Activated by substances in plasma and injured tissue
- Causes increased
- Dilation of blood vessels at the site of injury
- Permeability of local blood vessels
- Induces pain
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Clotting Mechanism
- Clots blood and mediates inflammation
- Some of the clotting mechanism products that are activated during tissue injury cause local vascular dilation and permeability by activating kinin
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Complement System
- Involves the production of a sequential cascade of plasma proteins
- They are present in blood in an inactive form
- A trigger (usually an antibody-antigen complex) initiates the sequence of steps
- These plasma proteins function in inflammation and immunity
- Some components cause WBCs known as mast cells to release histamine
- Histamine causes an increase in vascular permeability and vasodilation
- Other components cause cell death, form chemotactic factors for WBCs, and enhance phagocytosis
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macrophages
- The second type of white blood cell to arrive at a site of injury that was originally a monocyte; it participates in phagocytosis during inflammation and continues to be active in the immune response.
- Constitute 3% to 8% of WBC population
- Single round nucleus and do not have granular cytoplasm
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Prostaglandins
Cause increased vascular dilation and permeability, tissue pain and redness, and changes in connective tissue (CT)
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Lysosomal enzymes
- Act as chemotactic factors
- May cause damage to connective tissue and to the clot
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Endotoxin
- Produced by cell walls of gram-negative bacteria
- Serves as chemotactic factor; can activate complement, function as an antigen, and damage bone and tissue
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cytolysis
The dissolution or destruction of a cell.
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opsonization
The enhancement of phagocytosis by a process in which a pathogen is marked, with opsonins, for destruction of phagocytes.
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leukocytosis
- An increase in the number of white blood cells circulating in blood.
- Normal number of WBCs per mm3 of blood: 4000 to 10,000
- In a systemic inflammatory response, the number increases to 10,000 to 30,000/mm3 of blood.
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lymphadenopathy
The abnormal enlargement of a lymph node or nodes.
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fever
- An elevation of body temperature to greater than the usual level of 37°C(98.6°F)
- Controlled by the hypothalamus
- Pyrogens
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pyrogens
The fever-inducing substances produce from either white blood cells or photogenic microorganisms.
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leukopenia
A decrease of white blood cells circulating in blood
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Waldeyer's ring
The ring of lymphatic tissue formed by the two palatine tonsils, the pharyngeal tonsils, the lingual tonsils, and intervening lymphoid tissue.
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Antiinflammatory Therapy
- Nonsteroidal antiinflammatory drugs (NSAIDs)
- Acetylsalicylic acid (aspirin)
- Ibuprofen
- Steroidal antiinflammatory drugs
- Prednisone
- Antihistamines
- Cancer treatment drugs
- Methotrexate
- Sulfasalazine
- Leflunomide
- Cyclophosphamide
- Mycophenolate
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C-reactive protein (CRP)
A nonspecific protein produced in the liver, that becomes elevated during episodes of acute inflammation or infection.
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granuloma
A lesion composed of a collection of macrophages usually surrounded by a rim of lymphocytes that is form by of chronic inflammation.
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Hyperplasia
An enlargement of a tissue or organ resulting from an increase in the number of cells, the result of increased cell division.
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Atrophy
A decrease in size or function of a cell, tissue, organ, or entire body
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Hypertrophy
An enlargement of a tissue or organ resulting from an increase in the size of its individual cells, but not in the number of cells.
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regeneration
The process by which injured tissue is replaced with tissue identical to that present before the injury.
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repair
The restoration of damaged or disease tissue by cellular change and growth.
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Fibroblast
The cells that form fibers as well as intercellular substances.
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fibroplasia
The formation of fibrous tissue as usually occurs in healing.
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angiogenesis
The formation and differentiation of blood vessels.
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granulation tissue
The initial connective tissue formed in healing.
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epithelialization
The process of renewal of a new surface layer of ephithelium.
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myofibroblasts
Fibroblast that have some of the characteristics of smooth muscle cells, such as the ability to contract.
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keloid
The excessive scarring that mainly occurs in skin in some cases with healing.
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Factors delaying bone formation
- Blood supply at site
- Growth factors
- Edema
- Injury
- Infection
- Removal of osteoblast-producing tissuesExcessive or inadequate movement of bone tissue
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Factors influencing repair of bone
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osteoblast
The cells that form bone.
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Systemic factors that impair healing
- Malnutrition
- Immunosuppression
- Genetic connective tissue disorders
- Metabolic disorders
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Local factors that impair healing
- Bacterial infection
- Tissue destruction and necrosis
- Hematoma
- Excessive movement of injured tissue
- Poor blood supply
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necrosis
The pathologic death of one or more cells, or a part of tissue, or an organ that results from irreversible damage to cells.
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demastication
When tooth wear is increased by chewing and abrasive substances.
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Attrition
- Tooth-to-tooth wear
- May be observed in both primary and permanent dentition
- Bruxism
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Bruxism
- grinding of the teeth together for nonfunctional purposes.
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Abrasion
- pathologic wearing away of tooth structure or a restoration that results from repetitive mechanical habit. (toothbrushing)
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Abfraction
appears as wedge shaped defect at the cervical area of teeth. (stress)
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Erosion
- Loss of tooth structure resulting from chemical action without bacterial involvement.
- Bulimia
- Methamphetamine abuse
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Bulimia
- eating disorder characterized by binges, usually of very high caloric intake , followed by self induced vomiting.
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anorexia nervosa
eating disorder, intense fear of gaining weight and self-imposed starvation.
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methamphetamine
decrease salivary flow, craving for high sugar containing beverages combined with lack of hygiene care results in the extensive and rapid destruction of teeth that is called "meth mouth"
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