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Occupational Exposure to Infectious Agents

Mary A. Borg

July/August 2012 Issue - Expires Monday, August 31st, 2015

Inside Dental Technology


Because employers are required by the Occupational Safety and Health Administration (OSHA) to establish procedures to promote the health and safety of their workers, employers must assess the hazards and then take action to implement administrative controls, engineering controls, and the use of personal protective equipment to protect their workers. Prevention and control of communicable diseases is an important part of the dental laboratory’s health and safety program.

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OSHA’s concern arises from the fact that there are millions of healthcare workers in the United States who need to be protected. According to the US Bureau of Labor Statistics, there are an estimated 11 million healthcare workers, and that number includes dentists, dental assistants, dental hygienists, and dental technicians.1

The Bloodborne Pathogen Standard describes how employers must protect workers from exposure to potentially infectious items. Along with this standard, an excellent resource for how to protect workers is the Centers for Disease Control and Prevention’s (CDC) Guidelines for Infection Control in Dental Health-Care Settings–2003. These recommendations have had a significant impact on dental settings, including dental laboratories.

This review of the basic components of an Exposure Control Plan, the risk areas in a dental laboratory, and communicable diseases will assist in eliminating and minimizing cross contamination.

Part One: Components of an Exposure Control Plan

OSHA requires employers to develop an Exposure Control Plan that covers the following:2

Exposure Determination

Category I and II job classifications (Category I consists of athletic healthcare trainers, school custodians, plumbers, registered professional nurses and Category II consists of teachers and educational assistants who work with handicapped students, houseparents, dormitory attendants, and building maintenance workers).

Method of Compliance

Refers to use of Standard Precautions that must be observed to prevent contact with blood or other potentially infectious materials.

Engineering and Work Practice Control

Used to eliminate or minimize employee exposure. Where occupational exposure remains after institution of these controls, then personal protective equipment (PPE) shall be used. Work practices could include handwashing, no eating/drinking in risk areas, and good housekeeping.

An employer must also develop:

Infection Control Protocols

  • Covering and identifying all risk areas
  • Prepare written procedures and post in risk areas
  • Train workers upon hire and at a minimum annually, plus enforce procedures

Examine Exposure Controls

  • Document an annual review of the Exposure Control Plan and exposure controls
  • Assess in writing if controls are being followed—if not, what corrective action is required?

Provide Hepatitis B Vaccine

  • Educate workers in risk areas of potential occupational exposure
  • Offer immediately upon hire at no cost to employee
  • Document acceptance or refusal

Post Exposure Management

  • Follow Post Exposure Evaluation and follow-up procedures
  • Document actions

Part Two: Risk Areas in the Dental Laboratory

Pick-up and Delivery Personnel

Many dental laboratories employ drivers to transport cases between the laboratory and the dental office. The employer must train these workers about the risks they may encounter and how to protect himself or herself. Some of the risks can be:

Risk: The dentist or dental staff attempts to hand the driver an impression that is not packaged properly. The laboratory employee needs to be instructed on how to handle this situation. Solution: Instruct the driver not to handle these items unless packaged properly. OSHA and Department of Transportation (DOT) set these guidelines, ie, liquid-tight, tamper-evident, secondary container with biohazard emblem (Figure 1).2,4

Risk: Bags and/or boxes picked up at dental office are wet. Solution: Provide drivers with a plastic container that they can use to place the bags/boxes. Also train drivers that handwashing is still the cornerstone of all infection control. When handwashing is not possible, use an alcohol-based hand gel. Also consider supplying that product in company pick-up vehicles.


Most of the items delivered to the dental laboratory from dental offices are impressions, bites, and other items that have been in a patient’s mouth. The workers in this area must be instructed on the use of standard precautions. All items must be disinfected.

Some dentists provide certain medical information about the patient that is not needed by the dental laboratory to manufacture the prosthesis. Communication with the dentist is important to explain that the laboratory uses standard precautions and has no need to know the medical condition of the patient. Dental laboratories should inform their dental clients not to provide any medical history or condition of the patient on the prescription.

The fit of restorations can be compromised by disinfecting techniques.3 An effective infection-control protocol is not only important for the dental laboratory, but also for the dental office. Communication with the dental practice about the type of disinfectant that they are using and their method of disinfecting can help eliminate distortion.6

Disinfection Tips

  • Wear a mask, gloves, safety eyewear, and gown while disinfecting (Figure 2).
  • Even if the dental staff disinfected the items before shipment, the dental laboratory must protect its workers by performing its own disinfection.
  • Select an appropriate disinfectant. Check with the manufacturers of the impression material and the disinfectant to ensure that they are compatible.
  • Read the label and use the disinfectant according to manufacturer’s recommendations.
  • The CDC recommends using an intermediate-level, hospital-grade, EPA-registered disinfectant.3
  • Time the disinfection for the length of time to kill TB.3
  • Always time the actual disinfection of each item.

Proper preparation of the items being disinfected is important. Consider not only the removal of blood, bioburden, bloody cotton rolls, and/or bloody retraction cords, but also any chemical that the dental staff may have left on the impression from their disinfection of the item. Most disinfectants state on the labeling that the chemical must be applied to a clean surface (Figure 3). Here are some of the techniques that can be used to clean impressions and other items that have been in the mouth:

  • Rinse with water
  • Use a half-inch bristle artist brush and gently brush with liquid detergent
  • Gently scrub with a mixture of stone and water
  • Use enzymatic cleaner with ultrasonic

Note: The best time to clean and disinfect prostheses and impressions is as soon as possible after removal from the patient’s mouth before blood or other bioburden dries. Communication with your dental clients to inform them of the condition of impressions and other items that you are receiving from them can help to eliminate the extra steps required by you to remove blood.

Handling of Extracted Teeth

Occasionally you may receive extracted teeth from your dental client. The CDC Guidelines for Infection Control provide information on how to protect anyone handling or transporting extracted teeth.3 Also, OSHA considers extracted teeth as potentially infectious material that should be disposed of in medical waste containers. Extracted teeth sent to you for shade or size comparisons should be:

  • Cleaned
  • Surface-disinfected
  • Transported according to OSHA and DOT regulations that is in a liquid-tight, tamper-evident container with the biohazard emblem displayed.

It is best to return the extracted tooth to the dentist, especially if it contains amalgam, so it can be disposed of according to state and local regulations.

Model Department

Even though the items used to pour impressions are disinfected in the receiving area, there are ways that workers in this department could be exposed to potentially infectious items:

Partial embedded in an impression or pick-up case

  • Only the outside surfaces were exposed to disinfectant in the receiving area’s initial disinfection; therefore, when the items are separated they should be disinfected again (Figure 4).

Trimming back overextended borders on impressions

  • It is not uncommon for blood to be encapsulated inside impressions (Figure 5). Because the technician who performs this task faces the risk of being splattered with blood, the worker must wear a mask, gloves, safety eyewear, and gown to protect the entry routes, which are the skin, eyes, inhalation, and ingestion. The impression must then be disinfected. To avoid a duplication of disinfection, the laboratory can have someone from the model department go to the receiving area to trim back the impressions prior to the initial disinfection in receiving.

Note: If the technician is using a utility knife or other sharp instruments to trim, they must be trained on not only the safe use of the knife or any other sharp instruments, but also on disinfection procedures to be used to disinfect these items after use.

Die Trim

Transfer of oral microorganisms into and onto impressions has been documented. Movement of these organisms onto casts has also been documented. Certain microbes can remain viable within gypsum cast materials for up to 7 days. Ensure that workers who are grinding on models that were clinically poured are trained on the exposure possibilities, how to protect themselves with suction and PPE, and how to decontaminate equipment and other surfaces each day.

Denture Repairs

Because dentures received for repair and reline have been worn by patients, they are to be considered potentially infectious. They should be disinfected in the receiving area. After the repair or reline has been performed, then the instruments, equipment, pressure pot, and polishing wheels used on these items must be disinfected. Do not forget counters where any grinding was performed on these items.

Bacteria can grow in a warm, moist, dark area, so think about the pressure pot that could be a perfect incubator. Disinfect the pressure pot at a minimum at the end of the day. If it works into your procedures, you can isolate the repair in its own water source by placing the repair in a bag with water and then placing the bag into the pressure pot.

Shade Verification

Some dentists send their patients to the dental laboratory for shade verification—follow all state and local regulations. Disinfect anything that came in contact with the patient’s mouth after the patient is dismissed. An area that is commonly overlooked is custom staining. Dispose of anything that was used on the case that cannot be disinfected. Establish rigorous protocols for this area and train workers on your requirements.

Completed Cases

Appliances and prostheses should be free of contamination when delivered to the patient. State and local requirements can vary so verify with each state where dental clients are located and set your standard. The Texas State Board of Dental Examiners requires the dental laboratory to disinfect the finished devices prior to shipment to the dental client.7

Part Three: Communicable Diseases


The first case of human immunodeficiency virus (HIV) was diagnosed 30 years ago. Since then, more than 575,000 Americans have lost their lives to AIDS.9 An alarming estimate, published by the CDC, is that, even today, every 9.5 minutes someone in the United States contracts HIV.8 Currently, more than 1.1 million Americans are living with HIV. As published by the CDC, only prevention can stop this. Even though workers in a dental laboratory are not at a high risk of acquiring HIV due to the virus’ short lifetime outside the body, workers in the dental laboratory must still be trained on the risk.

Hepatitis B

The virus of most concern in the dental laboratory is Hepatitis B. This virus can live outside the body for 7 to 10 days. The CDC estimates that between 800,000 and 1.4 million Americans are chronically infected.5 Hepatitis is an inflammation of the liver. The incubation period after exposure is 6 weeks to 6 months. There is a vaccine available for protection.

Employers in dental laboratories must identify their Category I workers. These are the workers who are at risk of coming into contact with potentially infectious items. Those workers must be offered the Hepatitis B vaccine, which consists of three injections. The CDC recommends, and OSHA requires, that Category I workers receive a titer test 1 to 2 months after the third injection to determine if the worker responded to the vaccine.3 If the worker did not respond, then a second series must be offered. If the worker does not respond to the vaccine series, then the employer must ensure that the worker is properly trained on the risk in their job and be provided appropriate PPE.

Hepatitis C

Hepatitis C is the most common bloodborne infection in the United States.10 The CDC states that approximately 3.2 million Americans are chronically infected.10 This disease of the liver sometimes results in an acute illness, but most often becomes a chronic condition that can lead to cirrhosis of liver and liver cancer. The virus lives 16 hours to 4 days outside the body and can be detected within 1 to 3 weeks after exposure. There is no vaccine against Hepatitis C.

Other Infectious Diseases

Methicillin-resistant Staphylococcus aureus (MRSA), flu, measles, chicken pox, and other easily transmitted diseases should be included in your infection control training for all workers. These diseases can be easily transmitted from human to human. Dental technicians usually work in close proximity to each other, so ensuring that workers who are sick stay home is important for the protection of the entire workforce. The CDC provides up-to-date information on their website to help you with information on these diseases.

Post Exposure Management

OSHA requires that you have a post-exposure evaluation and follow-up procedure for any worker who is exposed to bloodborne pathogens. Document these incidents on the post-exposure evaluation and follow-up that can be downloaded from the OSHA website. The employer must take the appropriate steps to not only provide medical treatment for its worker, but must also contact the dentist to request a follow-up with the patient. Any worker involved in an exposure incident must be offered treatment and receive appropriate follow-up counseling.2


1. US Bureau of Labor Statistics. Occupational Employment Wages News Release. Updated May 17, 2011. Accessed February 14, 2012.

2. Occupational Safety and Health Administration. Occupational Safety and Health Standards, Toxic and Hazardous Substances, Bloodborne pathogens. Updated January 1, 2011. Accessed February 14, 2012.

3. Kohn WG, Collins AS, Cleveland JL, et al. Guidelines for Infection Control in Dental Health-Care Settings. Morbidity and Mortality Weekly Report. 2003;52(RR17):1-61.

4. US Department of Transportation. Title 49— Transportation. Chapter 1— Research and Special Programs Administration, Department of Transportation. Part 173— Shippers— General Requirements for Shipments and Packages. 173.196 infectious substances (etiologic agents) and 173.197 regulated medical waste.

5. The Centers for Disease Control. Hepatitis B FAQs for the Public. Updated June 9, 2009. Accessed February 20, 2012.

6. ADA Council on Scientific Affairs and ADA Council on Dental Practices. Infection control recommendations for the dental office and the dental laboratory. J Am Dent Assoc. 1996;127(5):672-680.

7. Texas Administrative Code. Required Sterilization and Disinfection. Title 22, Part 5, Chapter 108, Subchapter B, Rule §108.24.

8. U.S. Statistics. Updated February 20, 2012. Accessed February 20, 2012.

9. Centers for Disease Control and Prevention. HIV in the United States. Updated January 1, 2012. Accessed February 20, 2012.

10. Centers for Disease Control and Prevention. Hepatitis C Information for Health Professionals. Updated March 14, 2011. Accessed February 20, 2012.

To see an exclusive video from Mary Borg on infection control, visit us at:

Interested in earning more CE credit on Infection Control? Read Dr. Fluent’s and Dr. Molinari’s article at:

About the Author

Mary A. Borg
President and Senior
Compliance Advisor
SafeLink Consulting, Inc.
Cumming, Georgia

Figure 1  Potentially infectious items are packaged for transport Photographs courtesy of Georgia Dental Laboratory.

Figure 1

Figure 2  Personal protective equipment (PPE) is used for disinfection.Fig 3. A bloody impression that is not properly cleaned by the dental staff. Photographs courtesy of Georgia Dental Laboratory.

Figure 2

Figure 3   A bloody impression that is not properly cleaned by the dental staff. Photographs courtesy of Georgia Dental Laboratory.

Figure 3

Figure 4  A pick-up case needs to be disinfected after separation.

Figure 4

Figure 5  Blood is found inside the impression

Figure 5

COST: $0
SOURCE: Inside Dental Technology | July/August 2012

Learning Objectives:

  • Describe the components of an Exposure Control Plan.
  • Evaluate the risk areas in a dental laboratory and how to prevent exposure.
  • Understand the primary types of viruses and bacteria that are of concern in the dental laboratory.


The author reports no conflicts of interest associated with this work.

Queries for the author may be directed to