GUIDELINES FOR INTERNAL AND EXTERNAL INDICATORS.\Use internal indicators inside and external indicators on the outside of each instrument pack. When using glass test tubes during dry heat sterilization, ensure an internal indicator is in each test tube before the screw top is secured. When any indicator of a load test pack fails, resterilize it with a new test pack containing both chemical and biological monitors. Be sure to closely monitor the temperature, pressure, and sterilizing time of the load. Watch the timer to be sure it does not start before the correct temperature is reached. Watch for steam leaks from the sterilizer during the sterilization cycle. If the indicator again fails, notify the ICO and dental repair personnel. Log in the results from the failure, and secure the sterilizer from use until the results of the biological monitor can be evaluated.

Follow the manufacturer's instructions when reading the indicators. Please be aware that internal and external indicators are not replacements for biological monitoring. Only biological monitoring can tell you whether or not sterilization has actually occurred.

LIQUID STERILANTS.\Since liquid sterilants cannot be biologically monitored, their use is discouraged. In using these agents, the key is the time that instruments and equipment are in contact with the sterilizing agents. Test strips for concentration levels must be used according to manufacturer's instructions.

DISINFECTION

Disinfection is a less lethal process than sterilization, which kills disease causing microorganisms. This does not include the destruction of resistant bacterial spores. Disinfection is achieved by either chemical or heat means. Selecting an appropriate chemical germicide or heat disinfection method depends on what requirements need to be met for that particular product. The following are some of the criteria for effective chemical disinfection:

The degree of microbial kill or deactivation required

The composition and texture of the item being treated

The technical requirement and ease of use of the available agents

Regardless of the product selected, there is no single chemical or heat agent available today that will meet all these criteria. As always, follow label directions precisely. Give strict attention to the proper use of the product regarding mixing, dilution, method and duration of the application, temperature requirements, shelf-life, and if applicable, reuse life.

LEVELS OF DISINFECTION

The EPA classifies disinfectants as high, intermediate, or low level, based on the effectiveness and contact time of the solution and the biocidal activity of an agent against bacterial spores, mycobacterium tuberculosis, lipid and nonlipid viruses, and vegetative bacteria. Table 10-4 describes the level of disinfection required to kill the micro-organism named.

FACTORS INFLUENCING GERMICIDAL PROCEDURES

The factors associated with the micro-organisms, as well as those associated with the surrounding physical and chemical environment, influence the antimicrobial efficiency of the germicides. They are described next.

Nature of the Material

The easiest surface to disinfect is a smooth, nonporous, and cleanable one. If the materials are incompatible with disinfectant, damage and corrosion can occur.

Bioburden

Under a given set of circumstances, the higher the level of microbial contamination, the longer the required exposure to the disinfectant is needed. Additionally, resistant micro-organisms require longer exposure times.

Table 10-4.\Micro-organisms and Levels of Disinfection

Organic Debris Present

Blood, saliva, and other organic material may contribute to the failure of a germicidal process by either direct inactivation of the disinfectant or the actual layering of the micro-organisms on the instruments or equipment, thereby preventing penetration of the germicide.

Type and Concentration of the Germicide

Generally, when all other variables are constant, the higher concentrations of a chemical agent are more effective and require a shorter time to disinfect. Use of dilutions other than those specified by the manufacturer adversely affect some intermediatelevel disinfectants, specifically iodophors. In all instances, follow the manufacturer's recommendations.