Article
Contamination of gloved hands can occur through both direct patient contact as well as indirect contact by touching of environmental surfaces. There are two types of dental environmental surfaces: housekeeping and clinical contact surfaces. Housekeeping surfaces do not come into contact with hands or devices used during dental procedures (eg floors, walls and sinks). Housekeeping surfaces can be treated (sanitized) at the end of the work day. Clinical contact surfaces can readily become contaminated with patient fluids and micro-organisms (eg light handles and switches, three-way syringes and hoses, dental chairs arms and headrests, bracket tables and handpiece switches and hoses).
Microbial survival rates on environmental surfaces vary widely. Numerous factors (eg microbial numbers and environmental resistance, temperature, humidity and level of organic materials present) influence persistence. Accurately predicting survival times is not possible. Therefore, the best position is that viable microbes are present and need to be removed or killed.
There are two general approaches to surface asepsis:
Most dental facilities use a combination of covers and disinfection.
The Venn diagram (Figure 1) illustrates the concept that successful disinfection is achieved through the combined efforts of interrelated factors. These factors can also help in the selection of surface disinfectants useful in dental environments. Every facility is different. Each facility must determine which product(s) is/are the best choice(s).
Microbial kill claims and contact times
When dental environmental surfaces are visibly contaminated with blood, an intermediate-level disinfectant is needed. Such products are tuberculocidal and have a wide spectra of activity. Because most clinical contact surfaces in dentistry are non-critical in nature, many facilities in the absence of blood use hospital-level disinfectants, which kill test bacteria, including Salmonella choleraesuis, Staphylococcus aureus and Pseudomonas aeruginosa. Labels on the disinfectant list the micro-organisms the product can kill and the contact time required.
Contact time (or dwell time) is the length of time a disinfectant must remain wet on an environmental surface in order to be effective. This time is determined through laboratory tests. Because of improving formulations, contact times required today have decreased to several minutes; a rapid kill is always desired. Ideal surface disinfectants remain wet to be effective after a single application.
Compatibilities and safety issues
Both liquid disinfection (spray-wipe-spray) and disinfectant towelettes (wipe-discard-wipe) should be relatively compatible with surfaces being cleaned and disinfected. Repeated use for extended periods of time can deteriorate treated surfaces. Damaged surfaces become more difficult to disinfect successfully.
Disinfectants should also be relatively benign to users. Products should not be flammable, toxic or irritating. They should be easy to use. Also, the minimal level of personal protective equipment required needs to be known. Users should refer to cautions listed on product labels.
Pre-cleaning abilities
Disinfectants work best on relatively clean, modestly contaminated non-porous surfaces. Disinfectants have varying abilities to remove deposited organic materials (bioburden). Ideally, a product should be able both to clean and disinfect. Cleaning usually involves the presence of surfactants, such as detergent. Pre-cleaning is the first spray and wipe of the spray-wipe-spray method and wipe-discard when using disinfectant towelettes.
Other factors
Other factors are important when selecting the best disinfectant. These include an adequate shelf-life and use-life, modest cost, premixed (ready to use), acceptable odour, convenient forms, water soluble, present in spray and wipe formats, quality wipe materials and unaffected by organic materials. Well organized and informative labels are also desirable.
Effective disinfection involves two elements or components:
Effective surface disinfection is dependent on the combined effort of the best product for the situation teamed with proper practice procedures. Further information is available (Rutala WA. Selection of the Ideal Disinfectant. http://disinfectionandsterilization.org/selection-of-the-ideal-disinfectant/).