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After studying this chapter, the student will be able to do the following:
1. Describe an effective infection control protocol for handling impressions and dental appliances that are transferred between the following:
a. Dental operatory and the dental laboratory within the dental office
b. Dental operatory and an outside commercial laboratory
2. Discuss and demonstrate the procedure for disinfecting dental impressions.
3. Explain and demonstrate the procedure for disinfecting dentures and other dental appliances after they have been processed or adjusted.
4. Describe and apply the infection control protocol that must be followed when grinding or polishing dentures and other appliances.
5. Review the preferred method (or methods) of sterilizing or disinfecting instruments or items used during manipulation of dental materials and prostheses.
The primary goal of infection control is to prevent cross-contamination between patients and dental care providers. Because impressions or appliances contaminated by saliva or blood are often transported to and from in-office or remote dental laboratories, the potential for cross-contamination exists. Therefore, when these items are being handled, an infection control protocol must be explicitly communicated among and observed by the office staff as well as between the office and any remote dental laboratory. The Occupational Safety and Health Administration (OSHA) regulates the transportation of contaminated items between the dental office and dental laboratory. All items must be properly packaged and labeled.
Such an infection control protocol should include guidelines for the proper handling and disinfection or sterilization of impressions, dentures, appliances, and the equipment or materials used during the processing of these items. Attention must also be given to the personal protective equipment that is worn when handling these items and to the physical layout of the laboratory (see Chapter 20, Infection Control and Safety in the Dental Office).
Acceptable disinfectants include glutaraldehydes, iodophors, sodium hypochlorite, synthetic phenols, dual or synergized quaternaries, and sodium bromide and chlorine. However, all impression materials are not compatible with all disinfectants. Use of quaternaries or sodium bromide and chlorine for disinfecting impressions and prostheses is not found in the literature; however, if you select either of these chemicals for use as such in your dental office or laboratory, test it on samples of materials to check for compatibility. In addition, glutaraldehydes should never be sprayed because they are extremely toxic as aerosols.
I. Disinfection of Impressions
A. Personal Protective Equipment
Wear protective eyewear, an outer cover gown with long sleeves, a mask, and gloves when handling a contaminated impression until it has been disinfected.
B. Rinse the Impression
Immediately after an impression is taken in the dental operatory, rinse it under running water to remove any saliva or blood (Fig. 21.1). This step is essential for optimum disinfection of the impression.
FIGURE 21.1. Rinsing an impression with running water.
C. Disinfection Techniques
Once the impression has been rinsed and shaken to remove excess water, it must be disinfected. This may be accomplished by immersing the impression in or spraying it with an acceptable disinfectant (Table 21.1). Always refer to the manufacturer’s recommended disinfection technique for a particular material.
TABLE 21.1. Recommended Disinfectants for Impression Materialsa
aBite registrations are made of various materials and should be disinfected with the same chemical that is used on the impression. Incompatibility between materials and disinfectants, as well as between the same materials of different companies, may exist.
bUse only if another disinfectant is not readily available.
Adapted from Merchant VA. Infection control in the dental laboratory environment. In: Molinari JA, Harte JA, eds. Practical Infection Control in Dentistry. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2010:251–258; Miller CH, Palenik CJ. Infection Control and Management of Hazardous Materials for the Dental Team. 4th ed. St. Louis, MO: Mosby; 2010:208–209.
1. Disinfection of an Impression by Immersion
Disinfection by immersion is preferred over disinfection by spraying. Spraying may not be as effective because constant contact of the disinfectant with all surfaces of the impression cannot be assured.
a. Place the rinsed impression into a zippered plastic bag containing appropriate disinfectant (Fig. 21.2). Expel air to ensure contact of the entire impression with disinfectant. Seal bag.
b. Exposure time to a disinfectant should be that which is recommended by the manufacturer of the product. Polyether and hydrocolloid impression materials may be adversely affected by disinfectants; therefore, limit their immersion time to no more than 10 minutes.
c. Remove the impression from the disinfectant.
d. Rinse the impression with running water, and shake to remove excess water.
FIGURE 21.2. Impression immersed in disinfectant within a zippered plastic bag.