Parameters such as time, pressure and temperature vary according to the type of sterilizer, materials being being sterilized and individual models within sterilizer brands. The first step in determining the setting for the sterilizer is to refer to the manufacture’s instructions. Sterilizers are medical device, requiring clearance by the Food and Drug Administration before manufactures may offer them for sale. The FDA requires rigorous testing to ensure an adequate margin of safety in each cycle type described in the instructions Failing to follow the instructions of the manufacturer is ill advised, since it may result in inadequate sterilization of the, Instruments or devices in the sterilizer. It is never appropriate to use a household device, such as a toaster oven, for sterilization of dental instruments, devices, or equipment.
Steam autoclaves are the most commonly used type of heat sterilizer in dental practices. Two types of process employ steam under pressure. The difference between the two is the manner in which the machine evacuates the air from the sterilization chamber and then introduces the steam. Gravity displacement sterilizer rely on the forces of gravity to force air out of the chamber through air escape vents. The stream entering the chamber from the water reservoir displaces the air as it leaves the chamber, steam and a high temperature for a prolonged period has the ability to kill virtually all micro organism. This is the most common type of autoclave found in dental offices. A typical cycle for wrapped instruments includes heat-up and pressurization time, followed by a 15 to 30 minutes cycle during which sterilization is taking place (121°C at 15 psi). The sterilization cycle time decreases as the temperature is increased. It is important to use cycle times and temperatures described in the owner’s manual, and never to interrupt the sterilization cycle to remover or add items or for any other reason. Interruption of the cycle will result in instruments that are not sterile and therefore not safe for use on patients. After the sterilization cycle the sterilizer must depressurize and the packs remain in the sterilizer for drying. The drying phase may take anywhere from 20-45 minutes. The unit must only be opened after completion of the drying cycle. upon removal from the sterilizer, sterile packs must be stored in a clean , dry area. Packs that become wet, torn, contaminated, or otherwise compromised require re sterilization.
Prevacuum Autoclaves (Also Called Class B Or Type B Sterilizers)
use a variety of technologies to remove air from chamber before the steam enters, thus creating a vacuum to ensure elimination of air from the chamber. This is generally a more efficient means of pressurizing the chamber; therefore the operator may notice some minor time saving in the start-up of the prevacuum sterilizers. Most prevacuum sterilizers use a temperature of 132°-135° for 3-10 minutes to achieve sterilization. This higher temperature may be unacceptable for some items, such as Teflon-coated instruments. Total time for pressurization, sterilization, venting and drying is generally considerably shorter than that for gravity sterilizers-about 45 minutes.
Dry-Heat Sterilization( Convection And Stack Air)
Dry-heat sterilization employs high temperatures for extended periods to achieve sterilization of instruments. The method of heat circulation in dry-heat sterilizers is usually convection, which helps to ensure that the heat circulates through out the sterilization chamber during the process. Mechanical convection is more effective, the sterilizer contains a fan or bower that continually circulates the heated air to maintain a uniform temperature throughout the chamber. Most commercially available dry-heat sterilizers on the market today are of this type The higher temperature of a dry-heat sterilizer means that paper will melt. Specialized packaging material is available for dry-heat sterilizers. The manufacture’s instructions should be checked for compatibility of instruments, devices, and materials with the unit.
Unsaturated Chemical Vapor Sterilization
Unsaturated chemical vapor sterilization relies upon the use of a proprietary chemical that contains formaldehyde, alcohol and other inert ingredients, instead of water, to produce a vapor to promote the sterilization. Use of this proprietary chemical also results in the vapor having less humidity and therefore being less corrosive to sensitive instruments than if water were used.
Most cold sterilization solution render instruments sterile only after a 10 hour immersion. This prolonged chemical action can be more detrimental to the surgical instruments than the usual 20 minute autoclave cycle. If the instruments need to be “disinfected” only, cold sterilization is okay as disinfection will place in only 10 minutes. But keep in mind the difference between: STERILE- an absolute term (no living organism survives) and DISINFECTED– basically clean Always use the proper sterilization/ cleaning technique to render the instrument in required condition for use. For instruments with Tungsten Carbide inserts (Needle Holders, Scissors, Tissue Forceps), we do not recommended use of solution containing Benzy| Ammonium Chloride which will destroy the Tungsten Carbide Inserts.
See brochure for telephone and address of local representative or telephone Steritray TEl: +92 52 3550954 These instruction have been validated by the manufacture as being capable of preparing a device for re-use. It remains the responsibility of the re processor to ensure that the reprocessing has actually achieved the desired result. This normally requires validation and routine monitoring of the process. Any deviation by the re processor from these instruction should be properly evaluated for effectiveness and potential adverse effects