D R . S UL TA N Z A H I RSTERILIZATION INDENTISTRY
STERILIZATION & DISINFECTION• Sterilization is defined as the process where all the livingmicroorganisms, including bacterial spores are killed.• Sterilization can be achieved by physical, chemical andphysiochemical means. Chemicals used as sterilizingagents are called chemisterilants.• Disinfection is the process of elimination of mostpathogenic microorganisms (excluding bacterial spores)on inanimate objects. Disinfection can be achieved byphysical or chemical methods. Chemicals used indisinfection are called disinfectants. Differentdisinfectants have different target ranges, not alldisinfectants can kill all microorganisms.
IMPORTANCE OF STERILIZATION• Sterilization procedures are very important to anygood dental practice. These are a part of basiccare and handling of patients. Patients mouth areteeming with microbes, and any dental office thatsees a large number of patients a day has aninherent potential for spreading infectious germsbetween patients and dental staff, throughcontaminated instruments and surfaces. These canbe greatly minimized by following proper infectioncontrol procedures.
• Good dental infection control starts with thedentist’s room itself. A well-ventilated room with air-circulating devices prevents building up of aerosolsproduced from the dental drills. The sterile dentistand assistant are immunized against hepatitis, wearclean personal protective equipment—a scrubapron, eyewear, disposable gloves and facemasks.The patient is draped, and may be given aprotective ―face shield‖ to prevent skincontamination from the dental drill’s water spray.An anti-microbial mouth rinse just before a dentalprocedure is important to reduce contamination.
• The dental chair’s knobs and handles need to bechemically disinfected between patients.• Surgical procedures require more stringentmeasures to eradicate all chances of infection andneed special preparation of the dentist’s room. Thedentist, assistant and patient all need sterilizedgowns, and all instruments, drills, suction apparatushas to be completely sterilized.
STERILIZATION AND DISINFECTIONOF DENTAL INSTRUMENTS• According to the Centers for Disease Control,dental instruments are classified into threecategories depending on the risk of transmittinginfection.• Critical• Semi critical• Non critical
• Critical instruments are those used to penetrate softtissue or bone, or enter into or contact thebloodstream or other normally sterile tissue. Theyshould be sterilized after each use. Sterilization isachieved by steam under pressure (autoclaving),dry heat, or heat/chemical vapor. Criticalinstruments include forceps, scalpels, bone chisels,scalers and surgical burs.
• Semi-critical instruments are those that do notpenetrate soft tissues or bone but contact mucousmembranes or non-intact skin, such as mirrors,reusable impression trays and amalgamcondensers. These devices also should be sterilizedafter each use. In some cases, however, sterilizationis not feasible and, therefore, high-level disinfectionis appropriate.
• Non-critical instruments are those that come intocontact only with intact skin such as externalcomponents of x-ray heads, blood pressure cuffsand pulse oximeters. Such devices have a relativelylow risk of transmitting infection; and, therefore, maybe reprocessed between patients by intermediate-level or low-level disinfection.• An intermediate-level disinfectant (e.g., phenolics,iodophors, and chlorine-containing compounds).• A low-level disinfectant (e.g., quaternaryammonium compounds).
METHODS OF STERILIZATIONMicrobialControlMethodsPhysical AgentsChemicalAgentsMechanicalRemovalMethods
PHYSICAL METHODS OF STERILIZATION• Dry Heat Sterilization• Kills by oxidation effects•The oven utilizes dry heat tosterilize articles• Operated between 50oC to250/300oC.•A holding period of 160oC for 1 hris desirable.• There is a thermostat controllingthe temperature.•Double walled insulation keeps theheat in and conserves energy,
DRY HEAT STERILIZATION USE• To sterilize Forceps, Scissors, Scalpels, Swabs.• Pharmaceuticals products like Liquid paraffin, dusting powder, fatsand grease.
MOIST HEAT STERILIZATION• Kills microorganisms by coagulating their proteins.MOIST HEAT STERILISATION IS CARRIED OUT WITHFOLLOWING METHODS:• Temp below 100oC: ―Pasteurization‖, Inspissator.• Temperature at 100oC: Boiling.• Steam at atmospheric pressure: Koch/Arnold’s steamer.• Steam under pressure: Autoclave.
AUTOCLAVE• Autoclave consists of a vertical or a horizontal cylinder.• One end has an opening which is meant for keepingmaterials to be sterilized.• The lid is provided with a Pressure gauge, to measure thepressure• A safety valve is present to permit the escape of steamfrom the chamber• Articles to be sterilized are placed in the basket provided• Sterilization is carried out under pressure at 121º for 15minutes.
ETHYLENE OXIDE• Highly inflammable, mixed with inert gases – CO2, N• Especially for sutures, syringes & all dentalequipments
RADIATIONTwo types of radiations are usedNON –IONISINGIONISING• Non ionizing –• Infra Red radiation ( rapid mass sterilization of syringes,etc.)• Ultra Violet radiation (enclosed areas)• Ionizing – Gamma, X ray, cathode ray(plastics, syringes, oil, metal foils)
•Infection control measures notonly reduce the chances ofgetting a dental infection, theyalso reduce the risk of catchingserious diseases like HIV andhepatitis.