Chapter 20 Principles and Techniques of Disinfection Copyright 2003, Elsevier Science (USA). All rights reserved. No part of this product may be reproduced or transmitted in any form or by any means, electronic or mechanical, including input into or storage in any information system, without permission in writing from the publisher. PowerPoint® presentation slides may be displayed and may be reproduced in print form for instructional purposes only, provided a proper copyright notice appears on the last page of each print-out. Produced in the United States of America ISBN 0-7216-9770-4

Introduction During patient treatment, the equipment and treatment room surfaces are likely to become contaminated with saliva or by aerosol containing blood and/or saliva. Laboratory studies have determined that microorganisms may survive on environmental surfaces for different periods of time. Assume that if the surface has had contact with saliva, blood, or other potentially infectious materials, it contains live microorganisms.

Dental Treatment Room Surfaces Clinical contact surfaces Touch surfaces Transfer surfaces Splash Spatter Droplet surfaces

Managing Surface Contamination There are two methods to deal with surface contamination: Barriers Preclean and disinfect surfaces between patients

Types of Surface Barriers There is a wide variety of surface barriers available on the market today. All should be resistant to fluids to keep microorganisms in saliva, blood or other liquids from soaking through to contact the surface underneath. Some plastic bags are designed especially to the shape of items such as the dental chair, air-water syringe, hoses, pens, light handles, etc. Plastic-barrier sticky tape is frequently used to protect smooth surfaces such as touch pads on equipment, electrical switches on chairs, or x-ray equipment. Aluminum foil can also be used because it is easily formed around any shape.

Remember, if a surface cannot be easily and thoroughly cleaned and disinfected, it should have barrier protection.

Fig. 20. 1 A, Touch surfaces. B, Transfer surfaces Fig. 20.1 A, Touch surfaces. B, Transfer surfaces. C, Splash, spatter, and droplet surfaces. Fig. 20-1

Precleaning and Disinfection Precleaning means to clean before disinfecting. All contaminated surfaces must be precleaned before they can be disinfected. Even if there is no visible blood on the surface, it must be precleaned because even a thin layer of saliva on the surface can decrease the effectiveness of the disinfectant. Precleaning reduces the number of microbes and removes blood and saliva (also called bioburden).

Precleaning and Disinfection- cont’d These techniques are most effective when used on contaminated surfaces that are smooth and easily accessible for cleaning. Always wear your utility gloves, mask, protective eyewear, and protective clothing when precleaning and disinfecting. Surfaces that are irregular or textured are difficult or impossible to clean, therefore interfering with disinfection. Regular soap and water may be used for precleaning, but it is more efficient if you select a disinfectant that has the ability to clean as well as disinfect.

Fig. 20-2 The assistant shown here places clean wrap barriers on the handles of the operating light.

Disinfection Disinfection is intended to kill disease-producing microorganisms that remain on the surface after precleaning. Spores are not killed during disinfecting procedures. Do not confuse disinfection with sterilization. Sterilization is a process in which all forms of life are destroyed.

Disinfectants Versus Antiseptics Disinfectants are chemicals that are applied to inanimate surfaces (such as countertops and dental equipment). Antiseptics are antimicrobial agents that are applied to living tissue. Disinfectants and antiseptics should never be used interchangeably because tissue toxicity and damage to equipment can result.

Disinfectants Disinfectants are chemicals that destroy or inactivate most species of pathogenic (disease-causing) microorganisms. In dentistry, only those products that are Environmental Protection Agency (EPA)-registered hospital disinfectants with tuberculocidal claims (kills the tuberculosis bacteria) should be used to disinfect dental treatment areas. The Mycobacterium tuberculosis is highly resistant to disinfectants, and if a disinfectant will inactivate the M. tuberculosis, it will most certainly inactivate the less resistant microbial families (such as bacteria, viruses, and most fungi) on the treated surface.

The “Perfect Disinfectant?” If there were an ideal surface disinfectant, it would have a rapid kill of a broad spectrum of bacteria, have residual activity, minimal toxicity, and would not damage surfaces to be treated. In addition, it would be odorless, inexpensive, work on surfaces with remaining bioburden, and be simple to use. Unfortunately, no single disinfectant product on the market today meets all these criteria. When selecting a surface disinfectant, you must carefully consider the advantages and disadvantages of various products. Often the manufacturers of dental equipment will recommend the type of surface disinfectant that is most appropriate for their dental chairs and units.

Types of Chemical Disinfectants Iodophors are EPA-registered intermediate-level hospital disinfectants with tuberculocidal action. Because iodophors contain iodine, they may corrode or discolor certain metals and may temporarily cause reddish or yellow stains on clothing and other surfaces. Synthetic phenol compounds are EPA-registered intermediate-level hospital disinfectants with broad-spectrum disinfecting action. Phenols can be used on metal, glass, rubber, or plastic. They also may be used as a holding solution for instruments; however, phenols leave a residual film on treated surfaces. Synthetic phenol compound is prepared daily.

Types of Chemical Disinfectants- cont’d Sodium hypochlorite (household bleach) is a fast-acting, economic, and broad-spectrum intermediate-level disinfectant (1:100 dilution for surface decontamination). Disadvantages: It is unstable and must be prepared daily, has a strong odor and is corrosive to some metals. It is also destructive to fabrics and irritating to the eyes and skin; it may eventually cause plastic chair covers to crack. Alcohols are not effective in the presence of blood and saliva. They evaporate quickly and are damaging to certain materials such as plastics and vinyl. The American Dental Association (ADA), CDC, and the Office of Safety and Asepsis Procedures Research Foundation (OSAP) do not recommend alcohol as an environmental surface disinfectant.

Types of Chemical Disinfectants- cont’d Chlorine dioxide is an effective rapid-acting environmental surface disinfectant (3 minutes) or chemical sterilant (6 hours). Chlorine dioxide does not readily penetrate organic debris and must be used with a separate cleaner. Other disadvantages of chlorine dioxide are that it must be prepared fresh daily, it must be used with good ventilation, and it is corrosive to aluminum containers.