Chemical Vapor Sterilization

This process uses a mixture of chemicals, including alcohol, formaldehyde, ketone, acetone, and water, that are heated under pressure to form a sterilizing gas. Sterilization requires 20 minutes at 270F with 20 psi when instruments are either unwrapped or bagged following the manufacturer's instructions.

Figure 10-12.\Dry heat sterilizer.

Advantages to chemical vapor sterilization are as follows:

No corrosion, rusting, and dulling of instruments since water content is only 15 percent (if instruments are dry when placed in chamber).

Prevents destruction of dental items, such as endodontic files, orthodontic pliers, wires and bands, burs, and carbon steel instruments.

Instruments are dry at the end of the cycle.

The major disadvantage of this sterilization method is the requirement for adequate ventilation. Chemical vapors, particularly formaldehyde, can be released when the chamber door is opened, leaving a temporary but unpleasant odor in the area.

Chemical vapor sterilization is not routinely used in Navy dentistry. Consult the manufacturer's instructions for specific details on operation and required user maintenance.

Ethylene Oxide Sterilization

Ethylene oxide (ETO) gas uses relatively low temperatures for sterilization. Using a heated unit, sterilization can be achieved in 2-3 hours at 120F. However, a lengthy aeration time must follow each cycle.

Materials such as suction tubing, handpieces, radiographic film holders, and prosthetic appliances may be sterilized without adverse effects. Follow the manufacturer's instructions for safety precautions, operation, and maintenance. Because of the serious Occupation Safety Health Agency (OSHA) problems with ETO gas, COs of Naval Dental Clinics (NDCs) should not purchase new ETO equipment. Large naval hospitals with ETO capabilities in their CSR may use them to sterilize nonheat stable dental instruments and equipment.

Liquid Chemical Sterilization

The Food and Drug Administration (FDA) classifies chemical disinfectants that are sporicidal as disinfectants, the FDA classifies all sterilants. Since monitoring the liquid sterilization process is virtually impossible, treat these products as high-level disinfectants rather than sterilants. Be sure to follow the manufacturer's directions exactly.

Bead and Salt Sterilizers

Use bead and salt sterilizers only during the endodontic procedure for sterilization of clean metallic instruments. Do not use them to sterilize instruments between patients. Clean contaminated instruments with an alcohol saturated gauze to remove blood and debris before inserting into the bead and salt sterilizers. Monitor and record at least weekly the temperature in the sterilizer well. If using salt in place of beads in the sterilizer, line the well with aluminum foil to prevent corrosion.

CRITICAL CATEGORY ITEMS REQUIRING STERILIZATION

All critical category items require sterilization. Table 10-3 lists a variety of different dental instruments and materials and shows what type of sterilization or disinfection is effective and preferred for each particular item. It also lists methods that are effective and acceptable, effective but risk damage, and ineffective with risk of damage to materials. Sterilize critical category items before turning them in for service or repair.

Following BUMEDINST 6600.10, sterilize critical category items as follows:

Surgical instruments\Effective and preferred methods of sterilization are the steam autoclave, dry heat oven, chemical vapor, or ethylene oxide.

Handpieces\Handpieces include: low-speed motor attachments, sonic scaler, and tips. Follow manufacturer's instructions. See table 10-3, for recommended method of sterilization. Follow manufacturer's instructions for the cleaning of the fiber optic bundle.

Burs and diamonds\Clean burs and diamonds and dry before sterilizing. Many burs and diamonds are used only for single patient use. One accepted method of sterilization for burs and diamonds are to place them in a screw cap glass test tube (fig. 10-13) or an aluminum foil wrapped bur block and dry heat sterilize for 90 minutes at 320-345F. Place a chemical indicator in each tube or wrapped bur block. At least weekly, place a biological monitor in one tube or foil wrapped block during the first load of the day,. retrieve and send for culture testing following the manufacturer's recommendations.

Endodontic files and Gates-Glidden burs\ Arrange sets in file blocks and seal in peel packs before autoclaving. When additional files or burs are necessary, take them from a new package or from a file storage box and sterilize them in a bead or salt sterilizer before use. Use endodontic broaches once and discard into a sharps container. Dental Technician, Volume 2, NAVEDTRA 12573, chapter 7, illustrates and explains endodontic broaches.