Infection Control

1. General Principle

Aceso Dental USA is concerned with preventing the transmission of infectious diseases and cross-contamination. In particular, the oral environment is inhabited with commensal oral flora, and blood-borne pathogens are potentially present on incoming items that have had contact with the patient's mucosa.

On the other hand, pathogens and contaminants that came into contact with cases during processing at the laboratory could remain and pose a risk to patients when placed in contact with their mucosa.

As such, our main objective is to prevent cross-contamination before, during, and after processing and eliminate pathogenic microorganisms on items that are highly likely to come into contact with a patient's mucosa.

According to Spaulding Classification, these items are considered semicritical. The Guidelines for Infection Control in Dental Healthcare Settings (CDC, 2003) contain a specific section for dental laboratories to address what needs to do. It stated that incoming possibly contaminated items "should be thoroughly cleaned, disinfected with an EPA-registered hospital disinfectant with a tuberculocidal claim, and thoroughly rinsed." Also, the laboratory should establish a "separate receiving and disinfecting area" "to reduce contamination in the production area." Waste generated, such as disposable trays or impression materials, "can be discarded with general waste" unless otherwise falling under the category of regulated medical waste. Appliances and prostheses delivered should be disinfected with "an EPA registered hospital disinfectant (low to intermediate)," and the item should be placed in a "tamper-evident container" before returning.

While some materials (e.g., impression materials) may require specific disinfection procedures, a general disinfecting protocol for intermediate-level disinfection and for low-level disinfection is adopted for ease of application. Further, since EPA registration only applies to products sold within the United States, products with similar effects are selected for disinfection. The Guideline for Disinfection and Sterilization in Healthcare Facilities (CDC, 2008) is utilized to further explain the meaning of various levels of disinfection as well as the effectiveness of multiple chemicals employed as disinfectants. The 2008 Guideline stated that in that low-level disinfectants can kill "most vegetative bacteria, some fungi, and some viruses in a practical period of time (≤10 minutes)".

While intermediate-level disinfectants might kill "mycobacteria, vegetative bacteria, most viruses, and most fungi but do not necessarily kill bacterial spores." Chlorine products, also commonly referred to as household bleach, are "aqueous solutions of 5.25%-6.15% sodium hypochlorite", have a "broad spectrum of antimicrobial activity," is "fast-acting" and can "remove dried or fixed organisms and biofilms from surfaces." "Higher concentrations (1,000 ppm) of chlorine are required to kill M.tuberculosis," while concentrations as low as 100 ppm can be effective against some types of bacteria. Because household bleach contains "52,500 – 61,500 ppm available chlorine", a 1:50 dilution provides over 1,000 ppm of available chlorine, while a 1:200 dilution provides over 250 ppm of available chlorine.

Consequently, immersion in bleach solution diluted to 1:50 for 10 minutes is utilized for general intermediate-level disinfection unless the material is incompatible with sodium hypochlorite or cannot be immersed. For general low-level disinfection, saturation spraying of bleach solution diluted to 1:200 is employed. Sprayed items are given a minimum of 1 minute of exposure time. A list of disinfection protocols is shown in Table 1.