Alginate impressions are molds of a patient’s teeth and gums, used in dentistry to create models of oral structures. These impressions inevitably come into contact with saliva, and sometimes blood, during their removal from the mouth. As oral fluids contain various microorganisms, disinfection becomes a necessary step in any dental setting. This process helps prevent the potential transmission of pathogens to dental staff, laboratory technicians, and other patients, thereby maintaining a safe clinical environment.
Preparation for Disinfection
Immediately after removal from the patient’s mouth, alginate impressions require an initial rinsing procedure. Rinse the impression gently under cool, running tap water for approximately 15 to 30 seconds. This initial wash removes any visible blood, saliva, or other debris.
While rinsing significantly reduces the microbial load on the impression, it does not fully disinfect the material. Tap water rinsing alone reduces microorganisms by about 40-50%, but does not eliminate cross-infection. This preparatory step ensures subsequent chemical disinfectants act more effectively on remaining microorganisms, unhindered by organic matter. A gentle stream of water is important to avoid distorting the delicate alginate material.
Disinfection Solutions and Application
Selecting the appropriate disinfectant and application method is an important step in processing alginate impressions. Common choices include iodophors, specific dilutions of sodium hypochlorite (0.5% or 1%), and glutaraldehyde solutions (0.55% to 2%). It is important to follow manufacturer’s instructions for both the alginate material and the chosen disinfectant, as improper use can compromise the impression’s dimensional stability.
Two primary methods apply disinfectants: spraying and immersion. When spraying, apply the disinfectant thoroughly to all surfaces for complete coverage. A 0.525% sodium hypochlorite spray is effective in reducing microbial growth. Immersion, while effective, requires careful attention to contact time because alginate is a hydrophilic material and absorbs water.
Alginate impressions immersed in disinfectant solutions should be exposed for short durations, 5 to 10 minutes. For instance, a 0.5% sodium hypochlorite solution provides effective disinfection in as little as 5 minutes without significantly altering dimensional stability. A 2% glutaraldehyde solution also disinfects alginate impressions within 5 minutes. Exceeding these recommended immersion times, such as 15 or 30 minutes, can lead to the alginate absorbing too much water, resulting in swelling and dimensional distortion of the impression.
Post-Disinfection Handling and Storage
After the recommended disinfection time has passed, the alginate impression must be thoroughly rinsed under running water. This second rinse is necessary to remove any residual chemical disinfectant from the surface, which could otherwise interfere with the setting reaction or surface quality of the dental stone when the model is poured.
Once rinsed, the impression should be prepared for storage if it cannot be poured immediately. Place the impression in a sealed plastic bag. Maintain a 100% humidity environment within the bag, often by including a damp paper towel (without direct contact), to prevent water loss. Alginate impressions should be stored at room temperature and not refrigerated, as temperature extremes can affect their dimensional accuracy. Pouring the dental model as soon as possible after disinfection, ideally within 30 minutes, is recommended to preserve accuracy, as even short storage times, such as 15 minutes, can lead to subtle dimensional changes.