1. As a matter of fact, the dentist, dental assistant, dentalhygienist and dental technician are at risk of exposureto disease agents through contact with blood or otherpotentially infectious materials. So by studying and bycarefully following the infection control and safetyguidelines, all the team work can minimize the risks ofdisease transmission to himself and to the patients inthe dental office.All practitioners should incorporate recommended CDC, ADA and OSHA infection control guidelines into theirdaily practice .

2. CHAIN OF INFECTION All links must be connected for infection to takeplacePathogenSource(sufficient virulence& adequate numbers)Susceptible Host(i.e., one that is not immune)Entry Mode(allows pathogen tosurvive & multiply)(of transmission(portal that the from source to host)pathogen canenter the host) 3. Definitions:CDC:Center of Disease Control and Prevention .ADA:American Dental Association.ADAA:American Dental Assistants Association.OSHA:Occupational Safety and Health Administration.OSAP:Organization for Safety and Asepsis Procedures.EPA:Environmental Protection Agency.FDA :Food and Drug Administration.NIOSH:National Institute for Occupational Safety and Health. 4. Why , Who and whatWhy is infection control necessary in dentistry ?Dental staff and patients may be exposed to a wide variety of pathogenicmicroorganisms .Who is responsible for infection control in the dental office ?Each member of the dental team must follow the recommended guidelines .What should be done to prevent the transmission of disease in the dentaloffice ?The most effective ways to prevent the transmission of diseases includes :1) Hand washing2) Gloves3) Face masks4) Protective eye wear5) protective clothing6) instrument sterilization and disinfection 5. Diseases Transmission in Dental OfficeDiseases Transmission in Dental OfficeThe dental office should have an infection control program to prevent thetransmission of disease from the following :Patient to dental teamDental team to patientPatient to patientDental office to community ( include dental teams family )Community to dental office to patientTo prevent such infections, following is a list of all those procedures andprecautions that together constitute infection control. These guidelinesshould be followed each time treatment is performed because we are nevercertain of the patient's status, either because they themselves do not knowor because they have chosen not to inform their healthcare providers of theircondition. Following these guidelines for every patient is called "StandardPrecautions". 6. Standard Precautions1. IMMUNIZATION2. PATIENT SCREENING3. HAND WASHING4. BARRIER TECHNIQUES - Personal Protective Equipment (PPE) Rubber dam, Pre-procedural rinsing5. NEEDLE & SHARP INSTRUMENT SAFETY Occupational Exposure To Blood/Body Fluids7. SURFACE DISINFECTION8. radiographic asepsis9. laboratory asepsis10. infectious dental waste management & disposal6. INSTRUMENT STERILIZATION AND DISINFECTION 7. Modes of Diseases Transmission Direct contact with blood or body fluids Indirect contact with a contaminatedinstrument or surface Contact of mucosa of the eyes, nose, ormouth with droplets or spatter Inhalation of airborne microorganisms 8. A) Infection Control during the PretreatmentPeriod It is the period of protective equipment :An essential pretreatment procedure is the preparationof all personnel involved in patient care. This includesthe utilization of personal protective equipment (gown,eyewear, mask and gloves) and hand hygiene. 9. Infection Control During the Pretreatment PeriodThe process of infection control begins during the period ofpreparation for clinical treatment. Paying attention to infectioncontrol at this time has several payoffs. In addition to reducing therisk of transmission of infectious agents during patient care,thinking ahead will make the treatment session more efficient andwill also make the post treatment infection control process easierand more effective.1. Remove unnecessary items from the dental procedure area :The dental procedure area should be arranged to facilitate athorough cleaning following each patient.2. Preplan the materials needed during treatment.Set out all instruments, medications, impression materials,and other items that are needed for a procedure. Thinkingahead minimizes the need to search for additional items or toenter cabinets and drawers once gloves have becomecontaminated. 10. 3. Utilize disposable items whenever possible :The use of disposable items saves time during cleanupand decontamination and solves the problem of properreprocessing.4. Use prearranged tray set-ups for routine or frequentlyperformed procedures.Helps to eliminate the need to go into cabinets once you havestarted a procedure.5. Use individualized, sterilized bur blocks for each procedure. Using individualized bur blocks containing only the burs requiredfor that procedure helps to eliminate the contamination of other,unneeded burs and to make clean-up easier. 11. 6. If indicated, have the rubber dam setup on the tray.When a rubber dam will be used during a clinical procedure, italso should be included on the tray setup. In addition, includethose items needed for high-velocity evacuation. 12. 7. Identify those items that will become contaminated duringtreatment.While preparing the dental procedure area prior to beginning aclinical procedure, consider which items will becomecontaminated during treatment. Examples of such surfaces includecountertops, light handles, X-ray unit heads, tray tables etc. Decidewhether to use a barrier, e.g., plastic wrap to preventcontamination of these surfaces and items or to disinfect themwhen the procedure is complete.8. Review patient records before initiating treatment and placeradiographs on the view box.Do not leave the record on the countertop or handle it afterbeginning treatment. Place the record in a drawer or out of thedental procedure area, so that it doesnt become contaminated.Entries into the record should be done before and after theprocedure. 13. 9. Prepare personnel involved in patient care.An essential pretreatment procedure is the preparation of allpersonnel involved in patient care. This includes the utilization ofpersonal protective equipment (gown, eyewear, mask and gloves)and hand hygiene. 14. A .Handwashing and hand care :According to the U.S. Centers for DiseaseControl (CDC) , hand washing is the single mostimportant procedure for preventing the spread ofinfection. So , you must wash your hands each timebefore you put on gloves and immediately after youremove gloves . Handwashing is also required if youtouch contaminated instruments or surfaces duringworking .We should always use liquid soap during handwashing. Bar soap should never be used because it maytransmit contamination . 15. Hands Need to be Cleaned When Visibly dirty After touchingcontaminated objects withbare hands Before and after patienttreatment (before gloveplacement and after gloveremoval) 16. Personal protective equipment ( PPE )OSHA requires the employer to provide employeeswith appropriate personal protective equipment .Examples of PPE :1- Protective clothing2- Surgical masks3- Face shields4- Protective eyewear5- Disposable patient treatment gloves , and6- Heavy-duty utility gloves . 17. These PPE must be used wheneveryou : Performing tasks that could producesplash or spatter . Any contact with body fluids Perform other clinical activities thatrequire handling contaminated items e.g.radiographs , impressions , dentures orcontaminated equipment and surfaces . 18. We will study 4 aspects of eachone of these equipments : The purpose of using . Types . Guidelines for the use . Requirements . 19. 1) Protective clothing :Purpose : to protect the skinand underclothing from theexposure to saliva , blood ,aerosol , and othercontaminated materials .Types1) Laboratory coats 20. 2) Gown 21. 3) Surgical scrubs 22. Guidelines for the use of protective clothing1) It should not be worn out of the office for any reason .2) Change these work clothes at least daily, or more oftenif soiled, especially if they become visibly contaminatedwith blood.3) It must not be worn during eating or in resting rooms .4) It should be washed and laundered separately .Protective clothing requirements :1) Should be made of fluid-resistant material ( cotton ,cotton/polyester, or disposable jackets or gowns .2) Clothing should have long sleeves and a high necklineto minimize the amount of uncovered skin .3) Must cover dental personnel at least to the kneeswhen seated 23. 2) Protective masks :Purpose the mask worn over the nose and mouth toprotect the person from inhaling infectious organismsspread by the aerosol spray of the handpiece or air-watersyringe .Types the two most common types of masks are thedome-shaped and flat types .The dome-shaped Flat types 24. Guidelines for the use of protective masks : Masks should be changed for every patient or moreoften, particularly if heavy spatter is generated during thetreatment or if the mask becomes damp.Masks should be handled by touching only the side edgesto avoid contact with the more heavily contaminated bodyof the mask.Masks should conform to the shape of the face .Masks should not contact the mouth when being wornbecause the moisture generated will decrease the maskfiltration efficiency .Requirements : masks should be at least with 95% filtrationefficiency to remove particles 3 5 microns in diameter . 25. 3) Protective eyewear :Purpose eyewear is worn to protect the eyes againstdamage from : Aerosolized pathogens . Flying sharp debris such as scrap amalgam and toothfragments . Splattered solutions Caustic chemicalsGuidelines for the use of protective eyewear :1) OSHA requires the use of eyewear with both front andside protection ( solid side shields ) .2) Members who wear correction glasses or contact lensesmust wear protective eyewear with a side shields or a faceshield . 26. 3) It must be cleaned anddecontaminated after eachtreatment or patient visitaccording to the manufacturesinstructions .Types :Two types of protectiveeyewear used during patientcare :1) Glasses with protective sideshield , and2) Clear face shields . 27. Face shields :a chin-length plastic face shieldthat protects your eyes, nose, andmouth from spatter may be wornand replace the protectiveeyewear .However , a shieldcannot replace the mask becauseit does not protect againstinhalation of contaminated aerosolFace shield worn in addition to the mask 28. Patient eyewear :Patients should be provided with protective eyewearbecause they may subjected to eye damage from :1) Handpiece spatter2) Splashed dental materials3) Airborne bits of acrylic or tooth fragments 29. 4) Gloves :Purpose :Gloves must be worn by the dentist , dental assistant , anddental hygienist during all dental treatment to avoidcontact with the patients blood , saliva , or mucousmembranes or with contaminated items or surfaces .Types :The type of gloves used in dental practice shouldbe determined by the various procedures that areperformed in the practice as follow :1) Examination gloves usually are latex or vinyl . These arethe gloves most frequently worn by the dental teamduring patient care . 30. Examination gloves areinexpensive , available in a rangeof sizes from extra small to extralarge , and are ambidextrous (used for both right and left hands ). These gloves are nonsterile andserve only as a protective barrierfor the wearer .Examination gloves 31. 2) Overgloves are made of lightweight , inexpensive ,clear plastic . Overgloves may be worn over contaminatedtreatment gloves ( overgloving ) to preventcontamination of clean objects ( telephone , pen ,openingdrawers and cabinets ) that may be handled duringtreatment . Overgloves are discarded after a single use .To prevent contamination , an Overgloves isworn while using a pen . 32. 3) Sterile surgical gloves are used during surgicalprocedures such as oral surgery or periodontal treatment .Sterile surgical gloves are supplied in specific sizes andprepackaged unites to maintain sterility before use .Sterile surgical gloves 33. 4) Utility gloves are made from a puncture-resistant , heavymaterial which are not used for direct patient care . Utilitygloves may be washed , disinfected , or sterilized andreused and must be discarded when they become old . 34. Guidelines for the use of gloves : All gloves used in patient care must be discarded aftera single use. Torn or damaged gloves must be replaced immediately . Do not wear jewelry under gloves because , it may tearthe gloves . If the procedure is long , change the gloves each hour . Contaminated gloves should be removed before leavingthe chair side during patient car. Hands must be washed after glove removal and driedwell before regloving . 35. 5) Non-latex containing gloves occasionally , the healthcare providers or patients may experience serious allergicreactions to latex . The person who is sensitive to latex cansubstitute with gloves made from vinyl , nitrileand other non-latex containing materials .Hand dermatitis that developedfrom wearing latex gloves. 36. B) Infection Control during the treatment Period(Chairside Infection Control ) :The infection control procedures described inthe previous period will help you to reducethe risk of transmission of infectious agents.During treatment there are additionalprecautions that can be taken to furtherreduce infection risks.1) Use care when receiving, handling, orpassing sharp instruments.2) Take special precautions with syringes andneedles.3) Use a rubber dam whenever possible. 37. 4) Avoid touching unprotected switches, handles and otherequipment once gloves have been contaminated.5) Avoid entering cabinets once gloves have been contaminated. 38. c) Infection Control during the Post-Treatment PeriodAfter patient treatment , dental unite and treatmentroom surfaces are likely to become contaminated withsaliva or by aerosol containing blood . Also a primarysource of cross-contamination occurs when a memberof the dental team touches surfaces with contaminatedgloves .The laboratory studies have proved that microorganismsmay survive on environmental surfaces for long time . Forexample, Mycobacterium tuberculosis may survive forweeks . 39. Dental treatment room surfaces :Dental treatment room surfaces are classified as either : Clinical contact surfaces or General housekeeping surfaces .Clinical contact surfaces are those that are touchedby contaminated hands , instruments or by spatterduring treatment . It should be cleaned anddisinfected between patients .All the other surfaces , such as the walls and floors, are considered general housekeeping surfaces 40. Clinical contact surfaces :The clinical surfaces can be classified into threecategories :A) Touch surfaces : are directly touched andcontaminated during treatment procedures . Touchsurfaces include ;Dental light handlesDental unite controls andChair switches 41. B) Transfer surfaces :are touched by contaminated instruments such asinstruments trays .C) Splash , spatter , and droplet surfaces :countertops are a major example .Touch and transfer surfaces should be either barrier-protectedor cleaned and disinfected between patients . Inthe same time , splash , spatter , and droplet surfaces shouldbe cleaned at least once daily . 42. Dealing with surface contaminationThe goal of the two methods to deal with surfacecontamination are :1- To prevent the surface from becoming contaminatedby the use of a surface barrier .2- To preclean and disinfect the surfaces betweenPatients .Each method has advantages and disadvantages , and mostdental offices use a combination of surface disinfection andsurface barriers . 43. Surface barriers :Surface barriers are used toprevent contamination on thesurface underneath .All the surface barriers shouldbe resistant to fluids in orderto prevent microorganisms insaliva , blood , and otherliquids from soaking throughthe barrier and reach thesurface underneath .Chair Drapes 44. Film Dispenser 45. Some plastic bags are specially designed to the shapes ofthe dental chair , air-water syringe , and light handles . 46. Sticky tape as a plastic barrier is frequently used toprotect smooth surfaces , such as electrical switches onchairs and x- ray unite 47. Infection Control During the Post-TreatmentPeriod1. Continue to wear personal protective equipment duringclean-up: After patient care is completed, begin thecleaning and disinfection process by removingcontaminated gloves used during treatment, wash yourhands and use the utility gloves before beginning theclean up. Continue to wear protective eyewear, mask,and gown.2. Remove all disposable barriers : All of the barriersplaced before treatment, including light handle coversand countertop barriers, should be removed.3. Clean and disinfect all items not protected by barriers. 48. Cleaning and disinfection of the dental treatment roomsurfaces are important components in an effectiveinfection control program .PrecleaningPrecleaning means that all contaminated surfaces must beprecleaned before they can be disinfected . Precleaningreduces the number of microbes and remove blood , saliva, and other body fluids .Precleaning techniques are most effective whenused on contaminated surfaces that are smooth and easilyaccessible for cleaning . 49. Materials used for precleaning regular soap and wateralways used for precleaning . However , a disinfectantsthat can cleans as well as disinfect are present today .DisinfectionDisinfection is directed to kill disease-causingmicroorganisms that remain on the surface afterprecleaning .N.B always do not confuse disinfection with sterilization .Sterilization is the process in which all forms of lifeorganisms are destroyed .The term disinfectant is used for chemicals that areapplied for cleaning surfaces , such as countertops anddental equipment . 50. DisinfectantsDisinfectants are chemicals that destroy or inactivate mostspecies of pathogenic ( disease-causing ) micro-organisms .In dentistry , only those products that registered with theU.S Environmental protection Agency ( EPA ) withtuberculocidal action should be used to disinfect dentaltreatment areas .Ideal surface disinfectantThe ideal surface disinfectant must be rabidly kills a broadspectrum of bacteria , has residual activity , minimaltoxicity , odorless , inexpensive and does not damagesurfaces to be treated . 51. Disinfectant such as :Iodophors : Iodophors are EPA-registered hospital disinfectants withtuberculocidal action . It is recommended for disinfecting surfaces after dentaltreatment . Iodophors are usually effective within 5 to 10 minutes . Non-irritant and non-toxic . Unstable solution must be changed regularly . Because they contain iodine , iodophors may corrode ordiscolor certain metals and temporarily may cause red oryellow stains on clothing and other surfaces . 52. Synthetic phenol compounds : Are EPA-registered intermediate-level hospitaldisinfectants with broad-spectrum activity ( can kill a widerang of microbes ) that used for surface disinfection . Phenol can be used on metal , glass , rubber , or plastic . They also may be used as a holding solution forinstruments , however , phenols leave a residual film ontreated surfaces . Synthetic phenol compounds must be prepared daily . Non irritant , non-toxic and non-corrosive . 53. Sodium hypochlorite :Sodium hypochlorite is a fast-acting , economic and broad-spectrumintermediate-level disinfectant .Disinfectant effect observed after 10 minutes .The Centers for Disease Control and prevention ( CDC )currently recommended the use of up to 1 100 dilutionof sodium hypochlorite for surface decontamination .The disadvantages Unstable solution need daily preparation . It has a strong and unpleasant odor . Irritant for skin and eyes . Corrosive for some metals .hypochlorite is destructive to fabrics and may eventuallycause plastic chair covers to crack . 54. Alcohol :Ethyl alcohol and isopropyl alcohol have been used over theyears as skin antiseptics and surface disinfectants . However, alcohol are not effective in the presence of blood andsaliva droplets because of the rapid rate of evaporation willlimits the antimicrobial activity of alcohol . In addition ,alcohols are damaging to certain materials , such as plasticsand vinyl .The American Dental Association ( ADA ) , CDC , and OSAPdo not recommend alcohol as an environmental surfacedisinfectant . 55. Chlorine dioxide :Chlorine dioxide can be used as an effective , rapid-acting, environmental surface disinfectant ( 3 minutes ) or as achemical sterilant ( 6 hours ) .The disadvantages (1) it must be prepared fresh daily .(2) it is corrosive to aluminum containers 56. Classification of instruments and equipment :According to the Centers for Disease Control andPrevention, dental instruments are classified into threecategories depending on the risk of transmitting infection.1) Critical instruments are those used to penetrate softtissue or bone and should be sterilized after each use.Sterilization is achieved by steam under pressure(autoclaving), dry heat, or heat/chemical vapor .Critical instruments include forceps, scalpels, bone chisels,scalars, and burs . 57. 2) Semicritical instrumentsare those that do not penetrate soft tissues or bone butcontact oral tissues, such as amalgam condensers,air/water syringe , tips mirrors, intraoral radiographyaccessories, digital radiography sensors, and other dentalhigh-technology instruments . These devices should alsobe sterilized after each use. In some cases, however, high-leveldisinfection is appropriate. A high-level disinfectant isregistered with the U.S. Environmental Protection Agency(EPA) as a "sterilant/disinfectant" and must be labeled assuch. 58. 3) Noncritical instrumentsare those that come into contact only with intact skinsuch as external components of X-ray heads. Suchdevices have a relatively lowrisk of transmittinginfection and, therefore, may be reprocessedbetween patients by intermediate-level or low-leveldisinfection. 59. Managing contaminated sharps :Contaminated needles and other disposable sharps ,such as scalpel blades , orthodontic wires , and brokenglass must be placed into a sharps container .OSHA , CDC and the EPA classify sharps as infectiouswaste .According to OSHA regulations , disposable sharpsmust be placed in a puncture resistant , closable , andcolor-coded or labeled with the biohazard symbolcontainer immediately after use . 60. Biohazard symbol 61. Proper processing of contaminated dental instruments ina six-steps process as :1) Transport : transport contaminated instruments to theprocessing area .2) Cleaning : clean instruments with a hand-free ,mechanical process such as an ultrasonic cleaner orinstrument washer.3) Packing : warp/package instruments in appropriatematerials containing an external process indicator .4) Sterilization : place the packages in a single layers or inracks to increase circulation of the sterilizing agentaround the instruments . Operate the sterilizer according tothe manufactures instructions . Allow packages to coolbefore removing them from the sterilizer . 62. 5) Storage: Store instruments in a clean , dryenvironment in a manner that maintains the integrity ofthe package . Rotate packages so that those with theoldest sterilization date will be used first .6) Delivery : deliver packages to point of use in a mannerthat maintains sterility of the instruments until they areused . Inspect each package for damage . 63. Holding solution :If the instruments can't be cleaned immediately afterprocedures, they should be placed in a holding solution toprevent drying of blood and debris on the instruments .A holding solution is a liquid disinfectant/sterilizingsolution used to soak contaminated instruments beforethey are cleaned and sterilized. It has the purpose to: Decrease infectious microbes on instruments . Loosen and minimize debris before scrubbing orultrasonic cleaning . Minimize the physical handling of the instruments . 64. The holding solution must be:Non-corrosive liquid,Of low cost,Non-staining andReadily available.The holding solution should be changed at least twice dailyIt is important to use a covered container with a separateinstrument basket to ensure complete immersion.Remember , a holding solution is necessary only whencontaminated instruments cannot be processedimmediately . 65. The holding solution 66. Precleaning and packaging instrumentsPrecleaning is done in three ways:- Hand scrubbing- Ultrasonic cleaning-Instrument washing machine 67. Hand scrubbingThis method is unfavorable because it requires directhand contact with the contaminated instrument andaccidental injury from these contaminated items mayhappen.During hand scrubbing we must follow the followingprecautions1- Wear eye wear and puncture-resistant gloves (P.P.E ) .1- Clean only one by one .2- Use only a long-handled brush .3- Do not immerse items in soapy water or deep basinso you can see the sharp edges. 68. Ultra-sonic cleaning Ultrasonic cleaning is recommended in place of hand-scrubbingin order to reduce direct staff contact withcontaminated instruments. The ultrasonic cleaner works by producing sound waveswhich causes formation of bubbles in liquid . The bubblesare too small to be seen . The mechanical cleaning action of the bubblescombined with the chemical action of the ultrasonicsolution removes the debris from the instruments . Instruments should be processed in the ultrasoniccleaner until they are visibly clean . The time may varyfrom 5 to 15 minutes . 69. Automated washerIt looks similar to a householddishwasher. It uses acombination of very hotwater together with adetergent to remove theorganic material. It isconsidered as disinfectorbecause it subjects theinstruments to a level of heatthat kills most vegetativemicroorganisms. 70. Packaging instrumentsBefore sterilization the instruments must be packaged toprotect them from becoming contaminated aftersterilization .They can be contaminated by aerosols in the air , dust ,or contact with nonsterile surfaces .An additional advantage to packaging instruments is thatthey can be grouped into special setups . 71. Sterilization monitoringSterilization monitoringBecause sterilization failure can occur at any time, it iscritical to determine that dental instruments are properlysterilized or not because microorganisms can not be seenby naked eye.Nowadays, three forms for sterilization monitoring areused :PHYSICAL CHEMICAL BIOLOGICAL 72. Physical monitoring:Physical monitoring of thesterilization process involveslooking at the gauges andreadings on the sterilizer andrecording the temperatures,pressure, and exposure time.Remember that the temperaturerecorded is for the chamber, notthe inside of the pack. Therefore,problems with overloading orimproper packaging would notbe detected from the reading onthe gauges. 73. Chemical monitoring:Chemical monitoring involves the use of heat-sensitivechemicals that change color when exposed to certainconditions.The two types of chemical indicators are processindicators and process integrators.Process indicatorsThis is used externally outside the instruments packageslike autoclave tape and color change marking. Its aim is todetermine if the package is processed or not.They simply identify instrument packs that have beenexposed to a certain temperature. 74. They do not measure the duration or the pressure. Theyare useful only in distinguishing between packages thatwere processed and those that were not processed. Thiscan prevent accidental use of unprocessed instruments. 75. Process integratorsProcess integrators are placed inside instrumentpackages. They respond to a combination of pressure,temperature, and time. All sterilization factors areintegrated. Examples of process integrators includestrips, tabs, or tubes of colored liquid. 76. Biologic monitoringThis is the best way to determine if sterilization hasoccurred.Biologic monitoring , or spore testing, is the only way todetermine if sterilization has occurred. The CDC, AmericanDental Association recommend at least weekly biologicmonitoring of sterilization equipment .Biologic indicators (BIs), also known as spore tests, arevials or strips of paper that contain harmless bacterialspores (spores are highly resistant to heat).Method :Three BIs are used in testing. Two BIs are placed insideinstrument packs, and the sterilizer is operated undernormal conditions. 77. The third strip is set aside as a control. After the load hasbeen sterilized, all BIs are cultured. If the spores survivethe sterilization cycle (a positive culture), a sterilizationfailure has occurred. If the spores are killed (a negativeculture), the sterilization cycle was successful. 78. Sterilization in the dental office :The three most common forms of heat sterilization in thedental office are :Steam sterilization,Chemical vapor sterilization, andDry heat sterilization. 79. 1) Steam sterilization : involves heating water togenerate steam, producing a moist heat thatrapidly kills microorganisms. As the steamcompletely fills the sterilizing chamber, thecooler air is pushed out of an escape valve,which then closes and allows the pressure toincrease which increase the temperaturereaches up to 120 C which is higher than boilingwater . It is the heat, not the pressure thatactually kills the microorganisms. 80. A disadvantage of steam sterilization is that the moisturemay cause corrosion on some high-carbon steelinstruments. Distilled water should be used in autoclavesinstead of tap water, which often contains minerals andimpurities. Distilled water can minimize corrosion andpitting.0peration cycles :Dental office steam sterilizers usually operate through fourcycles :1) heat-up cycle 2) sterilizing cycle3) depressurization cycle 4) drying cycle 81. Flash Sterilizationinvolves sterilizing unpackaged instruments using shortexposure times. The instruments are placed in thechamber unwrapped. The sterility of the instruments isdefeated immediately when the instruments areremoved from the sterilizer.Flash sterilization should be used only for instrumentsthat are to be used promptly on removal from thesterilizer. 82. Dry-heat SterilizersDry-heat sterilizers operate by heating air and transferringthat heat from the air to the instruments. This form ofsterilization requires higher temperatures than steam orchemical vapor sterilization . temperature ranges between(160 C to 190 C) .The total cycle time :placing instruments in oven, heating to 170 C, timing for 1hour, and then cooling it from 22.5 hours .The advantage of dry heat is that the instruments will notrust if they are thoroughly dry before they are placed inthe sterilizer.The disadvantage of dry heat is the risk of damagingplastic and rubber instruments and also it need long time . 83. Chemical liquid sterilizationUsed for some types of plastics items that can damagedby heat such as some rubber dam frames , shade guides ,and x-ray film-holding devices .A liquid sterilizer such as 2% to 3.4% Glutaraldehydemust be used for sterilizing these items .Sterilizing in Glutaraldehyde requires a 10 hours contacttime, but if it is less than 10 hours, it is only disinfection,not sterilization .Glutaraldehyde must be used full strength ( not diluted (This material is highly toxic . 84. STERILIZATION FAILURESeveral factors can cause the sterilization process to fail .Examples of common mistakes include : overloading of sterilizer chamber . lack of separation between packs or trays in thechamber . wrong packaging material for method of sterilization . more than two layers of wrap, inhibiting penetration . sterilizer timer malfunction . improper cleaning of items to be sterilized. 85. Sterilization of hand pieces is recommendedwhenever possible :Hand pieces that are designed for steam sterilizationbetween uses are preferred. When a hand piece cannotbe heat or steam sterilized, chemical disinfection can beused as an alternative. 86. Best wishesfor youDr. Hesham Dameer Aseel