Infection control in dentistry prompts common questions about procedures

Packaging before sterilization and then carefully handling the packages afterwards will prevent contamination of the instruments before they are reused on another patient. Unpackaged instruments may become contaminated after sterilization by contact with dental aerosols and dust particles in the air, or by contaminants on surfaces or hands/gloves.

Chris Miller, PHD

Instrument processing

> Why package instruments before sterilization?

Packaging before sterilization and then carefully handling the packages afterwards will prevent contamination of the instruments before they are reused on another patient. Unpackaged instruments may become contaminated after sterilization by contact with dental aerosols and dust particles in the air, or by contaminants on surfaces or hands/gloves.

Prepackaging provides the most complete patient protection.

> Should instrument cassettes be bagged before sterilization?

Yes. Instrument cassettes certainly house the instruments in an organized fashion. Cassettes also prevent instruments from "bumping" against each other. In addition, direct handling is reduced (presumably minimizing the risk of sharps injuries).

Cassettes, however, do not prevent exposure to potentially contaminated air after sterilization. Air enters the perforations in the cassettes. The perforations are needed for ultrasonic cleaning and the entrance of sterilizing agents.

> How many times can you reuse sterilization bags?

None - unless the bag is sold as being reusable. At least one special sterilization pouch is sold as being reusable. Such pouches must be handled as described by the manufacturer and carefully checked for holes or tears between use.

> Why should instrument packs be dried after sterilization?

Wet packs can attract contaminants and dust from the air, transmitting them through paper wraps. Also, wet paper will tear when it is handled, and tears eliminate the wrap as an effective barrier.

> How do you reprocess burs without causing them to rust?

Carbon steel burs are very susceptible to rusting. To process them for reuse, it is necessary to clean them and then use a method of sterilization that will not induce corrosion. This would be dry heat sterilization or unsaturated chemical vapor sterilization (chemiclave).

Hepatitis B vaccination

> I got the hepatitis B vaccine, but it didn`t work. Why?

There are at least three reasons why this may occur in a few people:

- Some need more than the standard three inoculations.

- If someone is already a carrier of the hepatitis B virus, the vaccine usually does not work.

- Some people may just not be able to respond to this particular vaccine.

Seek the advice of a physician.

> When should I get my hepatitis B booster shot?

The CDC immunization practices advisory committee has still not recommended that a fourth shot be routinely given at any time after the original series of three inoculations. Seek the advice of a physician.

Surface Asepsis

> Is it necessary to clean and disinfect operatory surfaces that are being covered with plastic?

If the plastic barriers are being placed and removed properly, then the underlying surface should not become contaminated. If the surface does not become contaminated then it need not be disinfected.

> Some surface disinfectants in dentistry contain "quats" (quaternary ammonium compounds). Aren`t they outlawed in dentistry?

Disinfectants that contain only "quats" are usually not tuberculocidal, which means they have a reduced level of antimicrobial activity. Thus, in 1978, the ADA indicated that "quaternary ammonium compounds were not acceptable for disinfection of instruments and environmental surfaces in dentistry" (JADA 97:855-856, November 1978).

However, some of the newer formulations of "quats" also contain an alcohol which makes them tuberculocidal like most phenolics and iodophors.

> What are some OSHA-approved surface disinfectants for dentistry?

OSHA does not "approve" disinfectants or any other products. Also, the ADA no longer has a seal of acceptance program for surface disinfectants.

A guide that I use for selection of surface disinfectants is:

- EPA-registered.

- Tuberculocidal activity.

- Kills hydrophilic viruses (polio virus, for example).

> Is it OK for staff to handle contaminated laundry in the office?

Although staff are not to take protective clothing home for laundering, they can handle it in the office (sort, machine wash, and dry) if proper procedures are followed. These procedures are to be described in the written exposure control plan required for the office by OSHA. Staff can handle laundry when using proper barriers such as gloves, protective clothing, and leakproof bags for transporting wet items. Also, contaminated laundry should not be sorted in clinical areas.

Chris Miller is director of Infection Control Research and Services and professor of oral biology at Indiana University.

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