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Infection Control In The Oral Healthcare Setting Back to Course Index

 

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Oral healthcare facilities, including dental laboratories, like all healthcare facilities, are mandated to develop a written infection control/exposure control protocol predicated on a hierarchy of preventive strategies.

 

The use of appropriate infection control precautions is important for dental offices and laboratories.  Dentists, hygienists, and technicians, play a crucial role. Improper handling of contaminated items, such as impressions, casts, and other prosthetic appliances, can result in cross-contamination and possible cross-infection to other staff. When used together, routine use of recommended infection control procedures and protocols, along with effective communication between the dental practice and the dental laboratory, can provide a safe working environment for those with potential occupational risks. 

Historically, strategies to eliminate or reduce the risk of healthcare-associated infections (HAIs) were based on Universal Precautions, i.e., the concept that patients with bloodborne pathogens can be asymptomatic (unaware that they are infectious) and, therefore, all blood and body fluids contaminated with blood were treated as infectious. Exposure of dental healthcare professionals and their patients to a variety of bacterial, viral, and other microbial pathogens led to the development of infection control guidelines by the Centers for Disease Control and Prevention (CDC) and the American Dental Association (ADA). The Federal Occupational Safety and Health Administration (OSHA) mandated regulations describing a series of protocols and practices called the Bloodborne Pathogens Standard in December 1991.  As a result, effective infection control measures must be implemented and routinely used across the range of dental practices, including the dental laboratory. Standard Precautions, periodically expanded with new evidence-based elements, and Transmission-based Precautions provide the fabric for a hierarchy of preventive strategies to protect both oral healthcare personnel and patients and apply to contact with blood and all other potentially infectious material. 

 

Risk Prevention

Dental office and laboratory personnel are at risk for infection transmission as they pass from patient to patient, and handle impressions, casts, and other prosthetic appliances. Potential routes of transmission include direct contact with infected saliva or blood through cuts and abrasions, indirect accidental percutaneous exposure when using knives and other sharps items, and airborne infection from microbial-laden aerosols and spatter created during laboratory procedures. Cross-contamination is the greatest risk for exposure.  Many items are manipulated and processed in the dental laboratory and move back and forth between the office, operator, and the laboratory setting. One example includes how microorganisms on a dental impression may be transferred to dental casts and remain in set gypsum for up to 7 days. Thus, the potential for cross-contamination may occur from dental office to laboratory, and back to the dental office. Cross-contamination may also crop up within the laboratory from case to case, and may also occur from surface contact, contaminated handpieces, burs, rag wheels, pumice pans, and hands.

In order for an infection to be transmitted along any of these routes, specific conditions must be present: a viable microorganism, a reservoir that allows the microorganism to survive, a mode of transmission, a portal of entry, and a susceptible host. This is termed “the chain of cross-infection.” A primary goal of infection control is to minimize the spread of infection by breaking as many links in the chain as possible. In the dental laboratory, this would incorporate adherence to principles of aseptic technique, appropriate immunizations for laboratory personnel, the use of barrier techniques, and the implementation of standard precautions. Standard precautions dictate that all laboratory cases are handled the same way and are treated as if contaminated and infectious.

As mentioned above, dental offices and laboratories are required to comply with all relevant federal, state, and local regulations that affect their operations and employees. As a component of the OSHA regulations and CDC recommendations, all personnel must be evaluated for potential occupational exposures. At-risk employees must be offered the hepatitis B vaccination, and all employees are to be provided initial and annual training regarding bloodborne pathogens. If an employee’s responsibilities change such that exposure risk increases, the individual must be given additional training consistent with the new duties. It is also important to note that infection control policies in the dental office and laboratory must be written. They should be clear and concise, in a manner such that all personnel can clearly understand the policies. Written infection programs should be reviewed at least annually and periodically updated. All occupational exposure incidents should be recorded. Documentation of accidents should include the type of first aid administered, provision of healthcare professional counseling, post-exposure evaluation, and any indicated follow-up.

 

Infections

A disease is infectious if it can be spread by contact with infected people, animals, food, water, or objects.  If a disease can be spread by contact with an infected person, it is considered contagious.  So, don’t infectious and contagious mean the same thing?  No.  Consider this example:  Rabies is infectious because you can catch it from an infected animal.  But, rabies is not contagious because you can’t catch it from an infected person.

  • Before the discovery of penicillin in 1928, infectious diseases were the main cause of death in America.  Today, infectious diseases still cause many severe illnesses and deaths.
  • Every year, at least two million people catch an infection during their stay in a health care facility.  88,000 of them don’t survive the infection.
  • Nearly 200 million doses of antibiotics are given to hospital patients every day in America.
  • There are over 150 different antibiotics and some germs are resistant to all of them!
  • Health care workers use over 22 million pairs of gloves every year!
  • Fresh flowers can pose a risk to your clients especially if they have wounds.  Bacteria build up in the water inside the flower vase.  These bacteria can cause serious wound infections.
  • In the last ten years, over 700 antibacterial products have been developed for people to use in their homes.  These products include antibacterial cleaners, plastic bags, underwear, and bedding.  Most scientists believe that all these products are making the drug resistance problem worse.
  • One case of drug-resistant tuberculosis can cost up to $1 million to treat.
  • Around the world, one person dies of TB every ten seconds.
  • People are not protected against the flu until about two weeks after they’ve had a flu shot.
  • Around the world, five young people (ages 15 to 24) become infected with HIV every minute.
  • Worldwide, over 80% of all adults with HIV became infected with the virus through heterosexual intercourse.
  • The first AIDS case was diagnosed in 1982 in Los Angeles.  Since that time, nearly 22 million people have died from AIDS.
  •  In the year 2000 alone, HIV caused the death of approximately three million people worldwide, including half a million children.

 

 

The Facts About Hand Washing  

Hand hygiene procedures should be implemented at the beginning of each work cycle, before gloving, after de-gloving, before re-gloving, and anytime the hands are visibly contaminated with blood or bodily fluids.

 

Basic Information About Hand Washing:

 

  • The purpose of handwashing is to get rid of dirt and transient germs.  (There are many tiny bugs that live on our hands all the time.  But, transient germs contaminate our hands and may cause disease.)
  • Scientists have known for over 100 years that handwashing helps prevent infection.  Yet, people continue to get sick because their hands are not washed often enough. 
  • The handwashing procedure at your workplace probably calls for you to wash your hands for 30 to 60 seconds.  Yet, studies have shown that most health care workers spend less than 15 seconds washing their hands.

 

Remember!

 

  • Follow your workplace policy for washing your hands or for using a waterless hand cleaner.
  • Don’t make the mistake of thinking that wearing gloves takes the place of washing your hands!
  • Most of the germs on your hands hide under and around your fingernails.  Be sure to clean under your nails when you wash your hands.

 

Vaccinations

Oral healthcare providers should be vaccinated against vaccine-preventable infections, including Covid, in accordance with current state and federal regulations, as well as recommendations made by relevant professional organizations.

Immunization programs have markedly reduced the incidence of vaccine-preventable diseases. Today, a substantial percentage of morbidity and mortality from several vaccine-preventable diseases occurs in adults who escaped natural infection or immunization and who now are at increased risk of these diseases because of lifestyle, advancing age, the presence of certain chronic diseases, or occupation (e.g., healthcare workers).

 

Personal Protect Equipment 6

 

To prevent or reduce the risk of disease transmission, personal protective equipment should be worn by all oral healthcare providers when performing procedures that are likely to result in exposure to blood and bodily fluids.

Pathogenic organisms in blood and bodily fluids may come in contact with skin; conjunctival and oral mucosal tissues; and respiratory epithelium by inhalation of airborne microorganisms, i.e., droplets or droplet nuclei suspended in the air. Personal protective equipment (PPE) is designed to protect the skin and mucous membranes (eyes, nose, and mouth) and respiratory epithelium of healthcare providers from exposure to a source or reservoir of pathogenic organisms by contact transmission, i.e., direct or indirect contact transmission; and respiratory transmission, i.e., inhalation of droplets or droplet nuclei (airborne transmission).

 

Compliance

Personal protective equipment, which does not permit blood or OPIM to pass through to or reach street clothes, undergarments, skin, or mucous membranes under normal conditions of use and for the duration of time that the protective equipment is used should be provided and should be worn for by all oral healthcare providers.

  • Protective clothing
    Gowns or lab coats with long sleeves are worn to protect the forearms when splash, spatter, or spray of blood or bodily fluids to the forearms is anticipated.
    Protective clothing is changed daily, whenever it becomes visibly soiled, and as soon as possible if penetrated by blood or bodily fluids.
    Protective clothing is removed before leaving the work area.
    Dirty protective clothing is placed in designated areas for disposal or washing.

  • Task-specific gloves
    Non-surgical, surgical, or heavy-duty utility gloves are worn by all healthcare providers to prevent or reduce the risk of contaminating the hands with blood or bodily fluids and to prevent or reduce the risk of cross-infecting in the clinical process.
    To reduce the risk of latex-related allergies, only powder-free, low-allergen latex gloves; and non-latex, nitrile or vinyl gloves should be available.
    Non-surgical and surgical gloves are single-use items, which are used for only one patient and are then discarded.
    When torn or punctured, gloves are changed as soon as possible.
    Gloves may not be washed because it can lead to wicking (penetration of liquids through undetectable holes in the gloves) and subsequent hand contamination.
    Double gloving is acceptable for extensive oral surgical procedures.
    Heavy-duty utility gloves are worn for all instruments, equipment, and environmental surface cleaning and disinfection.
    Wearing gloves does not eliminate the need for hand hygiene.

  • Surgical masks 
    Surgical masks provided for routine use have a filtration efficiency of 95% for microorganisms greater than 3 microns.
    When a mask becomes wet from exhaled air or contaminated with infectious droplets, spray, or from touching the mask with contaminated fingers it is changed as soon as possible (between patients or even during patient treatment)
    Particulate filter respirators
    When airborne infection isolation precautions are necessary (g., transmission-based precautions for patients with TB), a National Institute for Occupational Safety and Health (NIOSH)-certified particulate-filter respirator (N95, N99, or N100) is used, which have the ability to filter. 3 µm particles with a filtering efficiency of 95, 99, and 99.7% respectively.

  • Protective eyewear
    Protective eyewear with solid side shields or a face shield is worn by OHCP during the clinical process likely to generate splash, splatter, and aerosols.
    Protective eyewear with solid side shields is also provided for the patients to protect their eyes from spatter and debris generated during the clinical process.
    Protective eyewear is cleaned with soap and water between patients.

  • Ventilation devices
    Mouthpieces, pocket masks, and resuscitation bags are used when CPR is administered.

 

Basic Information About Standard Precautions:

Standard precautions are basic infection control guidelines for you to follow as you perform your daily work.  These guidelines help prevent the spread of bloodborne diseases like AIDS and hepatitis C.

 

–Additional precautions are guidelines for protecting yourself and/or clients who need more than just basic infection control.  These extra precautions are divided into categories according to how a disease is spread:

 

  *Airborne:  These germs travel long distances in the air and cause diseases such as TB, measles, and chickenpox.

 

  *Droplet:  These germs travel long distances in the air and cause diseases such as influenza, strep throat, and the mumps.

 

  *Contact:  These germs are spread by touch and cause diseases such as scabies, cellulitis and hepatitis A.

 

 

Standard precautions also cover the proper way to handle client care equipment and to dispose of hazardous waste.  Be sure to follow your workplace procedures for these tasks.

 

 

The Latest Information About Standard Precautions

 

Some people experience allergic reactions to latex gloves.  Doctors are also seeing an increase in work-related asthma due to powder inside some gloves.  Be sure to let your supervisor know if you have any sensitivity to the gloves at your workplace.

 

Gowns, masks, and gloves are all types of personal protective equipment.  These items are used to protect you from infectious diseases.  However, you must also keep your client’s welfare in mind.  For example, if you don’t change your gown in between clients or you rinse off dirty gloves instead of using new ones, you run the risk of spreading germs from one client to another.  Be sure to follow your workplace procedure for the proper use (and disposal) of personal protective equipment.

 

 

Oral Workplace Controls

Work-practice controls should be implemented to prevent or reduce the risk of exposure.

The unique nature of oral healthcare settings, dental procedures, and instrumentation require specific strategies to prevent the transmission of infection. Work-practice controls are intended to eliminate or isolate hazards and promote safer behavior in the workplace. These take advantage of available technology to eliminate or isolate biohazards (blood or OPIM). When engineering controls are not available or are not practical, work-practice controls are implemented.

The direct patient care setting is central to the delivery of oral healthcare, but there are other environments within oral healthcare settings that support the delivery of clinical services, i.e., dental radiography and dental laboratory facilities. 

General considerations:

  • Eating, drinking, smoking, applying cosmetics or lip balm, and handling contact lenses should be prohibited in work areas.  
  • All items used in patient care should be stored in closed cabinets or drawers. Mobile carts used for patient care should not be cluttered with excess materials.
  • Bulk items should be covered to prevent contamination and caution should be exercised when retrieving such items to ensure that the remaining items are not contaminated.
  • Have appropriate instrument packs and supplies ready to begin treatment. This includes all necessary PPE (gloves, masks, eye protection, etc.) for the provider, assistant, and the patient.
  • Check all sterilized instrument packs and packages to ensure they are intact and the external chemical indicator has changed to the appropriate color.
  • Do not open packs in advance of the patient’s arrival.
  • If additional material is needed during treatment using an aseptic technique to retrieve needed items (e.g., sterile cotton forceps or pliers, an over-glove barrier, or remove gloves and perform hand hygiene).
  • Complete charting and computer entries after removing gloves and performing hand hygiene.
  • Place all disposable sharps in a designated sharps container.
  • Place instruments in a cassette tray (or properly labeled and approved container) for transport to the central sterilization room.

Given that the dental office and the laboratory are generally not in the same physical facility and the high potential for cross-contamination between the two settings, excellent communication between the two is essential for effective infection control.  The laboratory should clearly delineate infection control requirements for case submission to the dental office. The dental office and laboratory must reliably communicate the disinfection status of each incoming and outgoing case. If the status is uncertain, the process should be repeated. Thus, the prevention of cross-contamination should always be a prime consideration in the dental laboratory. Prevention measures include:

  • Organization of the dental laboratory into separate receiving, production, and shipping areas
  • Appropriate personal protective equipment
  • Frequent hand hygiene
  • Use of unit-dosing principles where appropriate
  • Proper laboratory case disinfection

Designated receiving, production, and shipping areas provide assistance in organizing and implementing an effective infection control plan. A receiving area should handle all items entering the laboratory and ought to have running water and hand-washing facilities. Countertops in this area should be covered with impervious paper or cleaned and disinfected on a regular basis. The receiving area technician must wear appropriate personal protective equipment (PPE) when receiving and disinfecting laboratory cases. After the items have been cleaned and disinfected, they can then be safely transferred to the production area. Because items in this area have already been disinfected, they no longer require special handling. The production area should be monitored to ensure that no contaminated items are allowed to enter. If an occupational injury occurs in this area of the laboratory, the involved prosthesis must be disinfected before being moved to another area of the laboratory.

Lastly, the shipping area is designated for the final inspection of items leaving the dental laboratory. This portion of the facility should be cleaned at least once a day and all case pans need to be cleaned before being used for another case. The disinfection of items to be shipped is only required if they have been contaminated to the point where handling is not safe. Receiving dental offices should disinfect all impressions and prostheses before insertion in a patient’s mouth. Please note that the shipping area of a dental laboratory should not function as the receiving area unless it has been properly cleaned and disinfected after receiving cases.

All clinical materials being sent to a laboratory should be cleaned and disinfected by the dental office that sent it, and identified as such. If the dental laboratory is uncertain about whether disinfection has been performed, the laboratory should carry out the process with an EPA-registered, intermediate-level disinfectant following the manufacturer’s instructions. The chemical disinfectants must be compatible with the dental impression materials used and must not affect the dimensional accuracy or surface texture. If the accuracy of the impression is compromised, the resulting gypsum casts will also be compromised, which may result in ill-fitting and nonfunctional prostheses. No single disinfectant is compatible with all impression materials, so the manufacturer of the impression material and disinfectant should be consulted. A laboratory might perform a “test-run” if a new combination of impression material and disinfectant is being used.

 

Cleaning and Disinfection (CDC Recommendations)

The first step in any infection control procedure is cleaning.   At the completion of work activities, countertops and surfaces that may have become contaminated with blood or saliva should be wiped with absorbent toweling to remove extraneous organic material, then disinfected with a suitable chemical germicide. A solution of sodium hypochlorite (household bleach) prepared fresh daily is an inexpensive and very effective germicide. Concentrations ranging from 5,000 ppm (a 1:10 dilution of household bleach) to 500 ppm (a 1:100 dilution) sodium hypochlorite are effective, depending on the amount of organic material (e.g., blood, mucus, etc.) present on the surface to be cleaned and disinfected. Caution should be exercised since sodium hypochlorite is corrosive to metals, especially aluminum.

 

Laboratory Supplies and Materials 

Blood and saliva should be thoroughly and carefully cleaned from laboratory supplies and materials that have been used in the mouth (e.g., impression materials, bite registration), especially before polishing and grinding intra-oral devices. Materials, impressions, and intra-oral appliances should be cleaned and disinfected before being handled, adjusted, or sent to a dental laboratory. These items should also be cleaned and disinfected when returned from the dental laboratory and before placement in the patient’s mouth. Because of the ever-increasing variety of dental materials used intra-orally, DHCWs are advised to consult with manufacturers as to the stability of specific materials relative to disinfection procedures. A chemical germicide that is registered with the EPA as a “hospital disinfectant” and that has a label claim for mycobactericidal (e.g., tuberculocidal) activity is preferred, because mycobacteria represent one of the most resistant groups of microorganisms; therefore, germicides that are effective against mycobacteria are also effective against other bacterial and viral pathogens. Communication between a dental office and a dental laboratory with regard to handling and decontamination of supplies and materials is of the utmost importance.

 

Ultrasonic Scalers, Handpieces, and Dental Units 

Routine sterilization of handpieces between patients is desirable; however, not all handpieces can be sterilized. The present physical configurations of most handpieces do not readily lend them to high-level disinfection of both external and internal surfaces (see 2 below); therefore, when using handpieces that cannot be sterilized, the following cleaning and disinfection procedures should be completed between each patient: After use, the handpiece should be flushed, then thoroughly scrubbed with a detergent and water to remove adherent material. It should then be thoroughly wiped with absorbent material saturated with a chemical germicide that is registered with the EPA as a “hospital disinfectant” and is mycobactericidal at use-dilution. The disinfecting solution should remain in contact with the handpiece for a time specified by the disinfectant’s manufacturer. Ultrasonic scalers and air/water syringes should be treated in a similar manner between patients. Following disinfection, any chemical residue should be removed by rinsing with sterile water.

Because water retraction valves within the dental units may aspirate infective materials back into the handpiece and water line, check valves should be installed to reduce the risk of transfer of infective material. While the magnitude of this risk is not known, it is prudent for water-cooled handpieces to be run and to discharge water into a sink or container for 20-30 seconds after completing care on each patient. This is intended to physically flush out patient material that may have been aspirated into the handpiece or water line. Additionally, there is some evidence that overnight bacterial accumulation can be significantly reduced by allowing water-cooled handpieces to run and to discharge water into a sink or container for several minutes at the beginning of the clinic day. Sterile saline or sterile water should be used as a coolant/irrigator when performing surgical procedures involving the cutting of soft tissue or bone.

 

Handling Of Biopsy Specimens

In general, each specimen should be put in a sturdy container with a secure lid to prevent leaking during transport. Care should be taken when collecting specimens to avoid contamination of the outside of the container. If the outside of the container is visibly contaminated, it should be cleaned and disinfected, or placed in an impervious bag.

 

Disposal Of Waste Materials 

All sharp items (especially needles), tissues, or blood should be considered potentially infective and should be handled and disposed of with special precautions. Disposable needles, scalpels, or other sharp items should be placed intact into puncture-resistant containers before disposal. Blood, suctioned fluids, or other liquid waste may be carefully poured into a drain connected to a sanitary sewer system. Other solid waste contaminated with blood or other body fluids should be placed in sealed, sturdy impervious bags to prevent leakage of the contained items. Such contained solid wastes can then be disposed of according to requirements established by local or state environmental regulatory agencies and published recommendations.

 

Specific Laboratory Guidance

Impressions may be cleaned by scrubbing gently and rinsing to reduce bioburden, and subsequently disinfected with an antimicrobial agent. Dental impressions may be disinfected by spraying, dipping, or immersing. The advantages of the spray method are that less of the disinfectant product is used, and often the same product may be used to disinfect environmental surfaces. However, the spray method may not be as effective as immersion due to the potential for pooling of the disinfectant in some areas, while other areas may remain dry secondary to undercuts in the impression. The spray method also releases chemicals into the air, increasing the potential for occupational exposures. The dipping or immersion technique requires complete coverage of the impression in the disinfectant. Shorter exposure times minimize possible distortion and deterioration of the surface quality of the resulting stone casts. However, the manufacturer’s instructions should always be consulted for their recommended procedures.

A contaminated dental impression will result in a contaminated dental cast. Because of potential damage to the model, it is more difficult to disinfect a cast than to disinfect an impression. Therefore, it is preferable to disinfect the impression prior to the fabrication of a cast. If a model must be disinfected, spraying with an EPA-registered, intermediate-level disinfectant followed by rinsing is recommended. The cast should then be placed on its end for drainage. If the cast is being disinfected for shipping, it should be allowed to dry before wrapping for shipment.

Contaminated prostheses should also be disinfected prior to being worked on in the dental laboratory. The prosthesis should be scrubbed with a brush using an antimicrobial soap to remove debris. If there is calculus adherent to the prosthesis, it should be placed in a sealed plastic bag or beaker filled with ultrasonic cleaning solution or calculus remover, and placed in the ultrasonic cleaner for the required time. The ultrasonic unit should be covered to reduce splashes and spatter, followed by cleaning in a detergent and then appropriate disinfection. After rinsing and drying, it is safe to continue performing laboratory work on the prosthesis.

Dental prostheses should not be stored in disinfectants prior to insertion. If a manufacturer’s recommended contact time is exceeded, there are potential corrosion risks for metal components. Dental prostheses may be stored in diluted mouthwash or water if desired.

The lathe in a dental laboratory presents unique safety and infection control risks. When using a lathe, dental technicians must wear protective eyewear. In addition, a Plexiglas® shield should be in position and the vacuum should be activated. The optimal pumice solution is made by adding surfactant soap and possibly a disinfectant solution to the mix. The pumice solution should be changed daily or more frequently if contaminated. All brushes, rag wheels, other laboratory tools, and the lathe should be cleaned and sterilized daily.

 

 

Postexposure Evaluation and Followup

Following exposure to blood or bodily fluids, healthcare providers should immediately undergo a confidential medical evaluation and subsequent follow-up by a qualified healthcare professional in accordance with current recommendations of the U.S. Public Health Service.

Exposure to blood or bodily fluids, including saliva (even when blood is not visible), must be considered potentially infectious. Consequently, post-exposure evaluation and follow-up are critical elements of a comprehensive infection control/ exposure control protocol.

  • Immediately after an exposure incident:
    Wash injuries with soap and water and apply an antiseptic agent (if available).
    Report the exposure incident immediately to the Office Infection-control Officer or other designated person

 

 

Transmission-based Precautions

To prevent the transmission of Mycobacterium tuberculosis (MBT), transmission-based precautions based on a three-level hierarchy of administrative, environmental, and respiratory-protection controls are to be implemented.

The primary risk of exposure to Mycobacterium tuberculosis (MBT) in the oral healthcare setting is in contact with patients with undiagnosed or unsuspected infectious tuberculous (TB) disease. A high index of suspicion and rapid implementation of precautions are essential to prevent and interrupt the transmission of MBT.

When reviewing the medical histories (initial and periodic), including a review of organ systems, all patients are routinely asked about a history of exposure to TB, latent TB infection, TB disease, medical conditions that increase the risk of TB, signs, and symptoms of TB.

 

 

Summary

Standard Precautions in combination with Transmission-based Precautions and Respiratory Hygiene/Cough Etiquette provide a hierarchy of preventive strategies to eliminate or minimize HAI’s. This guideline is designed to provide practical information for an effective infection control program in oral healthcare settings.

 

References

1. ADA Council on Dental Therapeutics. Infection control in the dental office. J Am Dent Assoc. 1978;97(4):673-677.

2. ADA Council on Dental Therapeutics, Council on Prosthetic Services and Dental Laboratory Relations. Guidelines for infection control in the dental office and the commercial dental laboratory. J Am Dent Assoc. 1985;110(6):969-972.

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

4. Centers for Disease Control and Prevention. Guidelines for infection control in dental health-care settings, 2003. MMWR. 2003;52(RR-17):1-66.

5. Department of Labor, Occupational Safety, and Health Administration. Occupational exposure to bloodborne pathogens; final rule. Fed Reg. 1991;56:64004-64182.

6.  https://www.aegisdentalnetwork.com

7.  Hussain SM, Tredwin CJ, Nesbit M, et al. The effect of disinfection on irreversible hydrocolloid and type III gypsum casts. Eur J Prothodont Rest Dent. 2006;14(2):50-54.

8. Ivanovski S, Savage NW, Brockhurst PJ, et al. Disinfection of dental stone casts: antimicrobial effects and physical property alterations. Dent Mater. 1995;11(1):19-23.

9. Kugel G, Perry RD, Ferrari M, et al. Disinfection and communication practices: a survey of U.S. dental laboratories. J Am Dent Assoc. 2000;131(6):786-792.

10. Merchant VA. Infection Control in the Dental Laboratory. In: Molinari JA. Practical Infection Control in Dentistry. 3rd ed. Philadelphia, PA: Lippincott, Williams and Wilkins; 2010:246-260.

11. Naylor WP. Infection control in fixed prosthodontics. Dent Clin North Am. 1992;36(3):809-831.

12. Plummer KD, Wakefield CW. Practical infection control in dental laboratories. Gen Dent. 1994;42(6):545-548.

13. Plummer KD, Dental Laboratory Relationship Working Group, Organization for Safety and Asepsis Procedures. Laboratory asepsis position paper. Annapolis, MD: OSAP Foundation.