Occupational hazards & infection control


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Occupational hazards & infection control

  3. 3. INTRODUCTIONInfectious diseases have scourged the world throughout historyA set of infection-control strategies common to all health-caredelivery settings should reduce the risk of transmission of infectiousdiseases caused by bloodborne pothogens such as HBV and HIVBecause all infected patients cannot be identified by medical history,physical examination, or laboratory tests, Centers for Disease Controland prevention (CDC) recommends that blood and body fluidprecautions be used consistently for all patients. These precautions,referred to as universal precautions,Transmission of HBV from dentists to patients has not been reportedsince 1 987, possibly due to increased adherence to universalprecautions - including routine glove use by dentists - and increasedlevels of immunity due to the use of hepatitis B vaccineEpidemiologic and laboratory data indicate that these infectionsprobably were transmitted from the dental health care workers(DHCWs) to patients, rather than from one patient to another.
  4. 4. IMMUNITYThe word immunity is derived from a Latin word‘immuni-s’ meaning ‘free from’ or exempt’.Immunity, therefore is the condition which rendersthe host non suceptible or resistant to infectiveprocesses caused by bacteria or their products.Immunity is therefore classified into 2 main divisions.1. Natural immunity2. Acquired immunity
  5. 5. NATURAL IMMUNITYThis is an inherited resistance to infection and notacquired during the lifetime of an individual. Theyinclude.• Phagocytosis of bacteria by WBC’s and cells of thetissue macrophage system.• Destruction by the acid secretions of the stomach.• Presence of certain chemical compounds in theblood likes lysozyme that destroys microorganisms.
  6. 6. ACQUIRED IMMUNITYThe immunity acquired during the lifetime of anindividual is known as acquired immunity. It may be,The immunity acquired during the lifetime of anindividual is known as acquired immunity. It may be,1. ACTIVE IMMUNITY2. PASSIVE IMMUNITY
  7. 7. ACTIVE IMMUNITYAcquired by an individual in response to theintroduction of microorganism or their toxin into thebody and the cells of the body take part in theformation of antibodiesFurther divided into natural & artificialNatural active immunity is acquired after an infectionArtificial active immunity is acquired artificially byinoculation of bacteria, virus or their products
  8. 8. COMMON TRANSMISSIBLEINFECTIONS IN DENTISTRYThe dental environment is associated with a significantrisk of exposure to various microorganisms.Many infectious agents may present in blood or saliva, as aconsequence of bacteremia or viremia associated withsystemic infections.These microorganisms may include cytomegalovirus,hepatitis B virus (HBV), hepatitis C virus (HCV), herpessimplex virus types 1 and 2, human immunodeficiencyvirus (HIV), mycobacterium tuberculosis, staphylococci,streptococci, and other viruses and bacteria - specifically,those that infect the upper respiratory tract
  9. 9. HERPES VIRUS INFECTIONThe herpes viruses are ubiquitous and are commonlypresent in the mouth. 50-90% of patients may beinfected and may shed one or more of the viruses atdifferent times. This shedding is particularly commonfor Epstein- Barr Virus (EBV) and Human HerpesVirus type 6 (HHV-6).Routine use of universal precautions, usage of glovesand avoidance of direct contact with oral mucosalHSV ulcers provide adequate protection against HSVin dental care workers.
  10. 10. ACUTE VIRAL HEPATITISViral hepatitis is currently divided into fiveprimarytypes,A, B, C, D. E
  11. 11. HEPATITIS BThe hepatitis B virus was first described in 1 965. The infective particle consists of an inner core plus anouter surface coat.The core contains DNA and DNA polymerase andreplicates in the infected liver cells.Hepatitis B surface antigen (HBs Ag) is found on thesurface of the virus.The first humoral response to HBV infection is thedevelopment of gM antibody to HBVAg (Anti HBc).It develops in all patients with HBV infection and persistsindefinitely.Anti- HBs is responsible for long-term immunity.
  12. 12. CLINICAL SIGNS & SYMPTOMS OFHEPATITIS BIt varies from a mild flu like illness to fulminant, fatalliver failure depending on the individuals generalhealth and immune responseThe onset of acute disease is generally insidious.The prodromal phase begins suddenly with anorexia,malaise, nausea, vomiting and fever. Urticaria andarthralgia may also occur.After 3 to 10 days, dark urine appears followed byJaundice.After I to 2 weeks, Jaundice fades and recovery beginsin 2 to 4 weeks
  13. 13. MODES OF TRANSMISSION INDENTISTRYHBV is transmitted both percutaneously and nonpercutaneouslyBecause dental treatment involves the use of small,sharp, contaminated instruments transferred betweendental care providers during treatment, multipleopportunities exist for inadvertent percutaneouswounds to the operator and staffHBV transmission during dental procedures occursprimarily in a horizontal mode among staff andpatients, predominantly from patient to care providerand less likely from care provider to patient.
  14. 14. TREATMENT OF HEPATITIS BEffective treatment is still not available.However, sub-cutaneous administration of interferonalfa-2b was effective in inducing a sustained loss ofviral replication.
  15. 15. PREVENTION OF TRANSMISSIONOF HBVHepatitis B vaccine• Plasma - derived vaccine• Recombinant DNAvaccine
  16. 16. PLASMA DERIVED VACCINE. The vaccine is given in 3 separate 20 mgintramuscular injections; the first two doses 1 monthapart and the third dose at 6 months (0,1,6).
  17. 17. RECOMBINANT DNA VACCINEIt provided an alternative to the plasma derivedvaccine.Administered vaccine is designed to contain 10 mg ofHBs Ag proteinThe regimen is same as that of the plasma derivedvaccineHowever it has been shown to induce protective anti-HBs in more than 99% of healthy adultsModifications have resulted in superior forms of theRecombivax HB vaccine
  18. 18. PASSIVE IMMUNIZATIONIt is usually required after accidental needlestickinjuries during treatment of patients.A single injection of hyper immunoglobulin, givenwithin 48 hours after injury, usually reduces theseverity of infection.Simultaneously active immunization should also beprovided.
  19. 19. HIV INFECTIONHuman immuno deficiency virus (HIV) is a member of the retrovirus family that can lead to Acquired Immuno DeficiencySyndrome (AIDS)A condition in which the immune system begins to fail leadingto life threatening opportunistic infectionsTransmission occurs through contact with blood and otherbody fluidsIn the early stages, the HIV infection may not be noticeable andmay be accompanied by symptoms such as weakness,arthralgias, or even be totally asymptomaticOn progression, HIV infection may be associated with a varietyof conditionsSome of the oral lesions associated with HIV infection and AIDSare Hairy Leukoplakia, Kapasis Sarcoma and Candidiasis
  20. 20. CLINICAL MANIFESTATION OF AIDS Unexplained diarrhea lasting longer than 1 month. Fatigue Malaise Loss of more than 10%bodyweight. Fever Night sweats Oralthrush Generalized Iymphadenopathy Enlarged spleen Opportunistic infections like, Pneumocystis carinii pneumonia Encephalitis Meningitis Cytomegalovirus rhinitis. Herpes simplex infections Tuberculosis
  21. 21. TUBERCULOSISTuberculosis is one of the oldest infectious diseases known tohumans.Mycobacterium tuberculosis is the organism which commonlyaffects the lungs but may involve any organ in the bodyTB mimics many respiratory conditions, therefore when thepractitioner observes a cough of more than 3 weeks of duration,sputum possibly tinged with blood, unexplained weight loss,and night sweats, the patient should be referred for a TB skintest and treatmentIf diagnosed with active infection the patient must be treatedtill pronounced non-infectious and then may access dental careExtra facilities are required for treating TB patientsFacilities should include negative air pressure treatment roomswith the air vented to the outside of the building
  22. 22. ROUTES OF TRANSMISSIONInfections may be transmitted in the dental operatorythrough several routes, including direct contact withblood, oral fluids, or other secretionsIndirect contact with contaminated instruments,operatory equipment, or environmental surfacesInfection via any of these routes requires that allthree of the following conditions be present(commonly referred to as “the chain of infection”): asusceptible host; a pathogen with sufficient infectivityand numbers to cause infection; and a portal throughwhich the pathogen may enter the host
  23. 23. CATEGORIES OF TASK IN RELATIONTO RISKCategory I:Tasks that involve exposure to blood, body fluid or tissues.Most tasks performed by the dentist, dental hygienist, dentalassistant and laboratory technician falls in this category.Category II:Tasks that do not involve routine exposure to blood, bodyfluids or tissues. However, unplanned category tasks mayoccasionally be required. Clerical or non-professionalworkers who may help clean up the office, handleinstruments or impression materials or send dentalmaterials to the laboratory fit into this category.
  24. 24. Category Ill:Tasks that involve no exposure to blood, body fluidsor tissues. A front-office receptionist, book keeper orinsurance clerk who does not handle dentalinstruments or materials would be a category Ill worker.
  25. 25. VACCINES FOR DENTAL HEALTHCARE WORKERSThe OSHA bloodborne pathogens final rule requiresthat employers make hepatitis B vaccinationsavailable without cost to their employees who may beexposed to blood or other infectious materials.CDC recommends that all workers, includingDHCWs, who might be exposed to blood or blood-contaminated substances in an occupational settingbe vaccinated for HBV
  26. 26. PERSONAL BARRIER TECHNIQUESFOR INFECTION CONTROL1. Washing and care of the hands DHCWs should wash their hands before and aftertreating each patient and after barehanded touchingof inanimate objects likely to be contaminated byblood, saliva, or respiratory secretions. Hands should be washed after removal of glovesbecause gloves may become perforated during useand DHCWs’ hands may become contaminatedthrough contact with patient material
  27. 27. 2. GlovesFor protection of personnel and patients in dental-care settings, medical gloves (latex or vinyl) alwaysmust be worn by DHCWs when there is potential forcontacting blood, blood- contaminated saliva, ormucous membranes.Non-sterile gloves are appropriate for examinationsand other nonsurgical proceduressterile gloves should be used for surgical procedures.Washing of gloves may cause “wicking” (penetrationof liquids through undetected holes in the gloves) andis not recommended
  28. 28. 3. GownsProtective clothing such as reusable or disposablegowns, laboratory coats, or uniforms should be wornwhen clothing is likely to be soiled with blood or otherbody fluids.Reusable protective clothing should be washed usinga normal laundry cycle, according to the instructions ofdetergent and machine manufacturersProtective clothing should be changed at least dailyor as soon as it becomes visibly soiled
  29. 29. 4. Masks / Protective eye wearChin-length plastic face shields or surgical masks andprotective eyewear should be worn when splashing orspattering of blood or other body fluids is likely, as iscommon in dentistry.When a mask is used, it should be changed betweenpatients or during patient treatment if it becomes wetor moist5. Rubber damAppropriate use of rubber dams, high- velocity airevacuation, and proper patient positioning shouldminimize the formation of droplets, spatter, andaerosols during patient treatment.
  30. 30. USE & CARE OF SHARPINSTRUMENTS & NEEDLESSharp items (e.g., needles, scalpel blades, wires)contaminated with patient blood and saliva should beconsidered as potentially infective and handled withcare to prevent injuriesUsed needles should never be recapped or otherwisemanipulated utilizing both hands, or any othertechnique that involves directing the point of a needletoward any part of the bodyEither a one- handed ‘scoop technique or amechanical device designed for holding the needlesheath should be employed
  31. 31. STERILIZATION OR DISINFECTIONOF INSTRUMENTSSterilization describes a process that destroys oreliminates all forms of microbial life and is carried outin health-care facilities by physical or chemicalmethods.When chemicals are used to destroy all forms ofmicrobiologic life, they can be called chemicalsterilants
  32. 32. Disinfection describes a process that eliminates manyor all pathogenic microorganisms, except bacterialspores, on inanimate objects.In health-care settings, objects usually are disinfectedby liquid chemicals or wet pasteurization.Each of the various factors that affect the efficacy ofdisinfection can nullify or limit the efficacy of theprocess
  33. 33. CLEANINGCleaning is the removal of visible soil (e.g., organicand inorganic material) from objects and surfaces andnormally is accomplished manually or mechanicallyusing water with detergents or enzymatic productsThorough cleaning is essential before high-leveldisinfection and sterilization because inorganic andorganic materials that remain on the surfaces ofinstruments interfere with the effectiveness of theseprocesses
  34. 34. As with other medical and surgical instruments, dentalinstruments are classifiedA. Critical: Surgical and other instruments used to penetrate softtissue or bone are classified as critical and should be sterilizedafter each use. These devices include forceps, scalpels, bonechisels, scalers and burs.B. Semi critical: Instruments such as mirrors and amalgamcondensers that do not penetrate soft tissues or bone butcontact oral tissues are classified as semicritical. These devicesshould be sterilized after each use.C.Noncritical: Instruments or medical devices such as externalcomponents of xray heads that come into contact only withintact skin are classified as noncritical. Because thesenoncritical surfaces have a relatively low risk of transmittinginfection, they may be reprocessed between patients withintermediate-level or low- level disinfection or detergent andwater washing, depending on the nature of the surface and thedegree and nature of the contamination.
  35. 35. The three most commonly used methods ofsterilization in dentistry are:1. The steam autoclave2.The unsaturated chemical vapour sterilizer(Chemiclave)3. DryheatovensOther methods are: Exposure to ethylene oxide gas Boiling water Ionizing radiation
  36. 36. AUTOCLAVEIt is an efficient, reliable and rapid method ofsterilization except for oils, greases and powders. All living organisms are rapidly destroyed at l2l °Ctemperature and 15 lbs. pressure for 1 5 minutes.The major problems are excess moisture, airentrapment and severe wetting
  37. 37. DRY HEAT STERILIZERThese sterilizers use hot air to kill microorganismsand do not cause corrosion.The standard dry heat sterilizing oven operates at anair temperature of about 320 F for exposure times of60-120 minutes.Closed containers can be used.
  38. 38. CLEANING & DISINFECTION OFDENTAL UNIT & ENVIRONMENTALSURFACESImpervious-backed paper, aluminum foil, or plastic coversshould be used to protect items and surfaces (e.g., light handlesor x-ray unit heads) that may become contaminated by blood orsaliva during use and that are difficult or impossible to cleanand disinfect.Between patients, the coverings should be removed (whileDHCWs are gloved), discarded and replaced (after unglovingand washing of hands) with clean material.After treatment of each patient and at the completion of dailywork activities, countertops and dental unit surfaces that mayhave become contaminated with patient material should becleaned with disposable toweling, using an appropriate cleaningagent and water as necessary.Surfaces then should be disinfected with a suitable chemicalgermicide.
  39. 39. A chemical germicide classified as a “hospitaldisinfectant’ and labeled for ‘tuberculocidal” (i.e,mycobactericidal) activity is recommended fordisinfecting surfaces that have been soiled withpatient material.These intermediate-level disinfectants includephenolics, lodophors, and chlorine- containingcompounds
  40. 40. DISINFECTION AND THE DENTALLABORATORYLaboratory materials and other items that have been usedin the mouth (e.g., impressions, bite registrations, fixedand removable prostheses, orthodontic appliances) shouldbe cleaned and disinfected before being manipulated inthe laboratory.These items also should be cleaned and disinfected afterbeing manipulated in the dental laboratory and beforeplacement in the patient’s mouth. A chemical germicide having at least an intermediatelevel of activity (i.e., “tuberculocidal h6spital disinfectant’)is appropriate for such disinfection.
  41. 41. 1. Receiving area: A receiving area should be established separate from the production area. Countertops and work surfaces should be cleaned and then disinfecteddaily with an appropriate surface disinfectant used according to themanufacturers directions.2. Incoming cases: Unless the laboratory employee knows that the case has been disinfected bythe dental office, all cases should be disinfected as they are received. Containers should be sterilized or disinfected after each use. Packing materials should be discarded to avoid cross contamination.3. Production area: Persons working in the production area should wear a clean uniform orlaboratory coat, a face mask, protective eyewear and disposable gloves. Work surfaces and equipment should be kept free of debris and disinfecteddaily. Any instruments, attachments and materials to be used with newprostheses or appliances should be maintained separately from those to beused with prostheses or appliances that have already been inserted in themouth. Brushes and other equipment should be disinfected at least daily.
  42. 42. HANDLING OF BIOPSY SPECIMENSIn general, each biopsy specimen should be put in asturdy container with a secure lid to prevent leakingduring transport.Care should be taken when collecting specimens toavoid contamination of the outside of the container.If the outside of the container is visiblycontaminated, it should be cleaned and disinfected orplaced in an impervious bag.
  43. 43. USE OF EXTRACTED TEETH INDENTAL EDUCATIONAL SETTINGSExtracted teeth used for education should be consideredinfective and classified as clinical specimen because theycontain blood.All persons who collect, transport, or manipulateextracted teeth should handle them with the sameprecautions as a specimen for biopsy. Universal precautions should be adhered to wheneverextracted teeth are handled, because preclinicaleducational exercises simulate clinical experiences and thestudents enrolled in dental educational programs shouldadhere to universal precautions in both preclinical andclinical settings. In addition, all persons who handle extracted teeth in
  44. 44. CONCLUSIONThe aim of infection control is to control iatrogenic,nosocomial infections among patients, and potentialoccupational exposure of care providers to disease causingmicrobes during provision of care.Disease transfer to the dentist and dental staff duringdental care is considered an “occupational exposure” to agiven pathogen while disease transfer from one patient toanother in the dental clinics is considered “cross-infection”.Therefore, the dental health care provider must beknowledgeable about the diseases commonly encounteredin the dental operatory and must follow high standards ofinfection control for the safety of the patients and thedental health care workers.
  45. 45. BIBLIOGRAPHYPreventive and community dentistry- Soben Peter 4theditionPreventive and community dentistry- Joseph johnTextbook of public health and dentistry by MaryaTextbook Of Preventive And Community Dentistryby Hiremath