GENERAL CATEGORIES OF LIQUID CHEMICAL AGENTS

A large variety of liquid disinfectants are available today, and it is probable that many new ones will become available in the future. When selecting a product, make sure that the label has an EPA registration number on it. Table 10-15, is a guide to chemical agents for disinfection and sterilization. Since they may be subject to change, be sure to read the manufacturer's instructions before using. Next, we will discuss the four most commonly used chemical agents, glutaraldehyde and chlorine dioxide based solutions, iodophors, and phenolics.

Glutaraldehyde-Based Solutions

These agents are available in several formulations differing in pH, concentration, use in dilution, and exposure time. They are classified as high-level disinfectants or sterilants.

Always wear impermeable gloves and protective eyewear when handling these solutions. Irritation of the hands is common and personnel are always at risk of splashes occurring whenever liquids are being

Table 10-5.\Guide to chemical agents for disinfection and sterilization.

handled, so direct physical contact between glutaraldehyde solutions and human tissues should be acceptable surface disinfectants because of the excessive amounts of exposure time required, corrosiveness, skin sensitization, and odor.

Immersed items must be rinsed with sterile water before using. Glutaraldehydes of 2 to 3.2 percent are avoided. When using these agents, they require proper FDA-registered. These solutions are not recognized as ventilation because their vapors are extremely toxic. 

Chlorine Dioxide-Based Solutions

Chlorine dioxide is an effective surface disinfectant or sterilant. These solutions may be used for high-level disinfection of semicritical items that are not subject to corrosion. It has a rapid action of 3 minutes for disinfection or 6 hours for sterilization. As with sodium hypochlorite (bleach), there are several disadvantages: chlorine dioxide must be discarded daily; has a 24-hour use life as a sterilant; and does not readily penetrate organic debris.

It must be used with protective eyewear and gloves because it is extremely irritating to the eyes and skin. It should always be placed in closed containers, and you must ensure adequate ventilation when using for surface disinfection. In addition, it corrodes aluminum containers.

Iodophors

Iodophors are classified as intermediate-level disinfectants or can be used as antiseptics if the product label claims tuberculocidal (lethal to mycobacterium tuberculosis) activity. They are compounds consisting of iodine and usually detergents to which the iodine quickly binds. Iodophor preparations are less irritating to tissues, cause less allergies, and do not normally stain skin or clothing. They should not be used on white or pastel vinyls that are subject to staining from repeated exposure to iodine. Their biocidal activity is accomplished within 10 to 25 minutes of exposure. To ensure tuberculocidal activity, fresh solutions must be prepared daily. As iodophors lose effectiveness, the color changes from amber to clear. Iodophors become somewhat unstable at high temperatures and can have a rapid loss of antimicrobial activity when inactivated by hard water and alcohol. Distilled or at least softened water is recommended to dilute the iodophors before using. Iodophors are EPA-registered and ADA-accepted as surface disinfectants. They may not be used as sterilants.

Iodophor antiseptics are useful in the preparation of oral mucosa for local anesthesia, surgical procedures, and handwashing. Not only does the iodophor remove the microbial populations from the skin, but also a residual antimicrobial effect remains on the scrubbed areas. Although iodophors are used as both antiseptics and disinfectants, the same product is never used for both.

Phenolics

Phenolics are also classified as an intermediatelevel disinfectant, provided the product label indicates a claim to tuberculocidal activity. They act as good surface spray cleaners and are effective in the presence of detergents. Phenolics are useful on metal, glass, rubber, and plastic, and are less toxic and corrosive than glutaraldehyde solutions. However, they create a film accumulation, can degrade certain plastics, and etch glass with prolonged exposure. They are very irritating and contact with skin and mucous membranes should be avoided. To prevent skin and eye irritation, protective gloves and eyewear must be worn during their use.

SEMICRITICAL CATEGORY ITEMS REQUIRING CHEMICAL DISINFECTION

Examples of semicritical items requiring chemical disinfection are three-way syringe tips, high-volume evacuator (HVE) and saliva ejector tips, radiographic positioning devices. For the chemical disinfection of semicritical items, use the following procedures:

Follow the manufacturer's instructions.

Thoroughly wipe the item with absorbent material saturated with an EPA-registered disinfectant.

Allow the disinfecting solution to remain in contact with the item for the length of time specified by the manufacturer.

Whenever possible, all semicritical items that can withstand sterilization should be sterilized.

Although nitrous oxide masks and breathing tubes fall into the semicritical category, if they are autoclavable, clean and sterilize them using steam heat. If not autoclavable, wipe after each use with two separate gauze pads saturated with a high-level disinfectant. If breathing tubes are not autoclavable, after each use, rinse inside and outside with running water, wipe and flush with a high-level disinfectant, and rerinse with water.

Note: All semicritical category items should receive high-level disinfection as shown in table 10-3.

NONCRITICAL CATEGORY ITEMS REQUIRING CHEMICAL DISINFECTION

Examples of noncritical category items requiring chemical disinfection are the following: dental delivery systems (DDSs), consisting of a chair, unit, and light; portable dental units; surgical table and chair; and X-ray apparatus. For the chemical disinfection of noncritical category items, use the following procedures: Disinfect the DDS at least daily.

Use disposable barriers since they reduce the number of surfaces requiring disinfection.

Change paper or plastic headrest and bracket tray covers after each patient. If headrest covers are not available, disinfect the headrest after each patient.

Disinfect hand-operated controls, switches, and handles after each patient.

Follow the manufacturer's instructions when disinfecting the lamp head and protective shield.

Flush HVE and saliva ejector tubing and cuspidor weekly with a central evacuation system cleaner. Use more often as needed. Follow the manufacturer's instructions.

Anesthetic cartridges for nonsurgical use should be dispensed under unit dose guidelines to prevent contamination of bulk supplies. Use only individual dose dental carpules and discard them after use. Always follow the manufacturer's instructions. Since disinfectants can diffuse through the diaphragm and contaminate the anesthetic solution, do not store cartridges in these agents.

Note: All noncritical category items require at least intermediate-level disinfection as shown in table 10-4.