Dental Laboratories And Infection Control

Dec. 1, 2012
When I was an assistant, I used to wonder about the dental lab that our office used to create dentures, partials, and crowns.

By Noel Brandon Kelsch, RDHAP

When I was an assistant, I used to wonder about the dental lab that our office used to create dentures, partials, and crowns. There were a couple of times when a crown arrived and the box was empty, and then there was the time that we received a denture for a patient not in our practice.

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One morning a patient arrived to have his crown seated and his crown was not in the office. The lab had promised to have it there the day before but the driver for the lab was off work due to illness. I drove to the lab to pick up the crown. No one was in the front of the lab so I walked into the back. A man in overalls stood at a lathe with a denture in one bare hand and a banana in the other bare hand. On the lab bench there was a mix of dentures, burs, crackers, notes, impressions, melted wax with a spatula stuck in it, chips of impression material mixed with chunks of stone, and a cup half full of coffee. I stood there and thought, “We should have visited here before we trusted our patients’ health to this lab.”

Studies have shown that microorganisms can be harbored in dental impression materials, including fungi and viruses. Then the impression materials are manipulated to create castings with gypsum. These microorganisms can thrive in this environment for up to seven days. The material, the processes of manufacturing, and transportation and storage make the process of producing prostheses a possible area for cross contamination.

The dental office and lab have the responsibility to follow infection control guidelines in handling impressions, prostheses, and materials that travel between the two offices. All the materials, tools, equipment, storage devices, and transportation systems involved in this process must be used in adherence with infection control protocols. This will prevent the possibility of cross contamination that can impact the lab staff, dental office staff, and patients.


Before using any dental lab, it is important to check out the lab. Ask:

  • Is the lab staff trained in infection control?
  • What is expected on your end regarding infection control as far as preparing the case for pickup?
  • How is the lab disinfecting the item before it is returned to the dental office for delivery to the patient?
  • What check systems are in place to assure infection control procedures are being followed?
  • Is the lab heat sterilizing lathe wheels, burs, and materials used in manufacturing that are heat tolerant, and following manufacturers’ and CDC recommendations for items that are not heat tolerant?
  • How is the lab disinfecting without distorting or damaging the impression materials? It is very frustrating to have to retake impressions.
  • Are the surfaces that the lab is manufacturing on being cleaned and disinfected between cases to prevent cross contamination?
  • Are single-use items (such as wax) being used once and disposed of?

The Centers for Disease Control Guidelines should be followed by everyone involved in the process. Here are their basic guidelines:

1. Use personal protective equipment including eye/face protection, chemically resistant utility gloves, surgical mask, and clinic jacket.
2. Use an EPA registered hospital grade disinfectant, at least intermediate level, having a TB claim. Clean, disinfect (allow the proper contact time), and rinse. Consult the manufacturers to find out the stability of the materials and their recommendations for hospital grade disinfectant use. Materials compatibility can vary from product to product even though they have the same basic ingredients. 3. Clean and heat-sterilize heat tolerant items used in the mouth, such as impression trays.
4. Follow the manufacturer’s instructions for cleaning and sterilizing or disinfecting items that become contaminated, but do not normally come in contact with patients. These include articulators, burs, polishing points, and lathes. If instructions are not available, heat-sterilize heat tolerant items and clean and disinfect with an intermediate grade EPA registered hospital disinfectant.

Make the lab staff and dental office staff aware of what is required regarding disinfectant techniques. Confirm that the protocols are followed on both ends. You can add the requirements to the lab prescription/ticket so that the process can be confirmed or checked off on both ends.

After my visit, we no longer worked with the lab with the disappearing crowns and mismarked dentures. They simply were not reliable and they put our patients in harm’s way. Infection control is a vital part of the process of manufacturing dental prostheses. It is important for all dental offices to develop an agreement with the dental lab regarding the standards and procedures involved in infection control. RDH

Simple Steps For Dental Impressions

  1. Rinse under tap water to remove as much debris as possible.
  2. Disinfect the impression using an intermediate level hospital grade disinfectant following the contact time that is recommended.
  3. Rinse under tap water to remove the residual chemicals.
  4. Shake in the sink to remove adherent water.

NOEL BRANDON KELSCH, RDHAP,, is a syndicated columnist, writer, speaker, and cartoonist. She serves on the editorial review committee for the Organization for Safety, Asepsis and Prevention newsletter and has received many national awards. Kelsch owns her dental hygiene practice that focuses on access to care for all and helps facilitate the Simi Valley Free Dental Clinic. She has devoted much of her 35 years in dentistry to educating people about the devastating effects of methamphetamines and drug use. She is a past president of the California Dental Hygienists’ Association.

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