Many dental care professionals are at risk for occupational exposure to a variety of hazardous chemicals and situations. Being unaware of the potential hazards in the work environment makes them more vulnerable to injury.
Let’s take a closer look at some of the potential health hazards associated with working in a dental lab.
Methyl methacrylate- This is used in making dentures and plates. It can be absorbed into the body by inhalation, through the skin, and by ingestion. It is irritating to the eyes, skin, and respiratory tract. Repeated and prolonged exposure can cause skin sensitization and asthma, as well as adverse effects on the nervous system.
Electroplating chemicals- The process of electroplating can release hazardous contaminants into the air that pose a variety of risks to the dental lab worker. The contaminants include various acid and alkaline mists that can cause respiratory and skin problems.
Metals such as beryllium, chromium, cobalt, and nickel can cause lung problems. These metals in alloys are used for castings of bridge framework and other dental prosthesis components.
Repetitive motion disorders- A range of injuries to the muscles, tendons, nerves, ligaments and joints of arms, hands wrists, shoulders, neck and upper back are common in the dental office setting. These injuries result from damage to the body over a period of time. If not treated, they can result in chronic pain and permanent disability.
Noise- grinding, sandblasting, and other dental lab machinery can make noise that can cause hearing loss.
Chemical sterilants- These are used to sterilize impressions and prosthetic devices, received from dental offices, contaminated with blood and saliva. Sterilant chemicals include aldehydes, phenols, and quaternary ammonium compounds. These chemicals may cause lung problems and dermatitis.
Silicosis is a disabling and incurable lung disease, and can be diagnosed in dental laboratory workers. However, it is preventable. Silicosis is caused by breathing in fine dust containing crystalline silica. Once in the lungs, this dust then causes damage that stops the body from using oxygen properly. Breathing in dust containing silica has been linked to other diseases, such as tuberculosis, kidney disease, and lung cancer.
Dental labs materials that contain silica:
The best method to stop silica exposure is to eliminate materials containing crystalline silica. However, this method is not feasible for sandblasting machines. In this case, aluminum oxide is one of the many acceptable substitutions to silica.
When there are no good substitutes, dust exposure should be minimized through the use of local exhaust ventilation systems. These systems capture dust and transport it to a dust collection system.
The worker should also wear a respirator when other control methods are not available or do not work properly. The type of respirator recommended is, at a minimum, a half-mask air-purifying respirator with type N-100 particulate filters.
Wet wiping, wet moping, and vacuuming with a HEPA vacuum are also recommended. Dry sweeping, dry dusting, use of compressed air, and use of ordinary vacuum cleaners should be avoided because they reintroduce the dust into the air.
Beryllium, atomic number 4, is a brittle, steel-gray metal found as a component of coal, oil, certain rock minerals, volcanic dust, and soil. Beryllium is the second lightest of all metals and is used in a wide variety of applications. In its elemental form, beryllium has the unique properties of being light weight and extremely stiff. It is used as a metal alloy in dental appliances.
OSHA is concerned cases of chronic beryllium disease (CBD) are occurring among dental laboratory technicians working with dental alloys containing beryllium.
CBD is a serious lung disease that can be disabling and even fatal. The serious disease may occur among dental laboratory technicians when they inhale dust containing beryllium when working on items such as dental crowns, bridges, and partial denture frameworks made from dental alloys containing beryllium.
Symptoms of Chronic Beryllium Disease include:
It is important to note NOT all individuals with these symptoms have CBD. These can be symptoms of other conditions which may also require medical attention. Not all people with CBD have all of these symptoms.
A 53-year-old woman who had worked as a dental laboratory technician for 13 years was diagnosed with CBD in May 2000. From 1987 to 1995, her daily work involved sandblasting beryllium dental alloy, cutting the metal sprue from the alloy with a high-speed grinder, removing the bubbles with a hand-held electric grinder and deburrer, and setting the restoration to make sure it fit the die. While performing this work, the worker wore a surgical-type paper mask. Although a household-type wall vacuum system with movable hoses was available for cleanup, the laboratory was reported to be very dusty.
Beginning in 1996, the woman worked in a different dental laboratory, where her duties included the grinding of porcelain restorations, sandblasting, metal finishing, and polishing restorations with rouge. The dental technician also was involved in clean-up activities, which included using a household-type dry vacuum, emptying the bag daily by taking it outside and shaking it, washing the bag, and hanging it out-side to dry. Shaking the bag produced a dusty cloud. Although this lab used a beryllium dental alloy, it did so much less often than the dental laboratory where this worker had previously been employed. At the second laboratory, work was performed without the use of a mask or hood. Airborne beryllium samples were not taken at either of the dental laboratories where this woman worked.
In 1997, the laboratory technician was diagnosed as having sarcoidosis. The diagnosis was based on the results of additional diagnostic procedures that identified a positive beryllium lymphocyte proliferation test result and abnormal lung pathology, physiology and function. She is currently experiencing symptoms of CBD including dry cough, decreased energy, and shortness of breath after walking up one or two flights of stairs or after walking rapidly on a horizontal surface.
Controlling the exposure to beryllium can be done through engineering controls, work practices, and personal protective equipment (PPE).
Engineering controls are the first line of defense in employee protection. Therefore, employers should provide appropriate engineering controls, such as isolating the source and using ventilation systems to control dust. Employers also need to train their workers in work practices to ensure that dental laboratory technicians’ exposures to beryllium are maintained below the current OSHA PELs.
Ventilation is one of the most important engineering controls available to the industrial hygienist and dentists for improving or maintaining the quality of the air in the occupational work environment. Broadly defined, ventilation is a method of controlling the environment with air flow.
The following work practices should be used to ensure that the exposures of dental laboratory technicians to beryllium are reduced:
Many dental offices use x-ray machines because they are useful diagnostic tools to see potential damage and tooth disease in patients. According to the American Dental Association, dental x-ray exams are safe, but they do require very low levels of radiation exposure. This makes the potentially harmful effects very small to the patient.
Dental X-ray tools and techniques are designed to limit the body's exposure to radiation and every precaution is taken to ensure that radiation exposure is “as low as reasonably achievable” (the ALARA principle). Therefore, a leaded apron minimizes the patient exposure to the abdomen and should be used when any dental x-ray is taken.
Occupational exposure in dental settings is far lower than that in hospitals and medical offices. According to the National Council on Radiation Protection and Measurements (NCRP), the total limit for occupational exposure is 50 millisieverts (mSv) in one year. In addition, the lifetime occupational effective dose is limited to 10 mSv times the number of an individual’s age. The NCRP concludes that occupational exposure for dental personnel will not exceed these limits. For pregnant dental personnel, the radiation exposure limit is 0.5 mSv per month.
State laws and regulations set specific requirements for the use of ionizing radiation (which includes X-rays).
Contact the state radiation protection program to determine specific requirements for:
Radiographic training requirements for dental office personnel frequently differ from and are less rigorous than those of medical personnel who take X-rays. Training requirements for dental office personnel typically are found in state dental practice acts or dental board regulations.
The Bloodborne Pathogens Standard (29 CFR 1910.1030) is the most frequently requested and referenced OSHA standard affecting medical and dental offices. Some basic requirements of this standard include:
An exposure can be defined as a percutaneous injury (needlestick or cut with a sharp object) or contact of mucous membrane or nonintact skin (exposed skin that is chapped, abraded, or with dermatitis) with blood, saliva, tissue, or other body fluids that are potentially infectious.
Exposure incidents might place dental health care personnel at risk for hepatitis B virus (HBV), hepatitis C virus (HCV), or human immunodeficiency virus (HIV) infection, and therefore should be evaluated immediately following treatment of the exposure site by a qualified health care professional.
When evaluating occupational exposures to fluids that might contain HBV, HCV, or HIV, health care workers should consider that all blood, body fluids, secretions, and excretions except sweat, may contain transmissible infectious agents. Blood contains the greatest proportion of infectious bloodborne virus particle titers of all body fluids and is the most critical transmission vehicle in the health-care setting.
During dental procedures, it is predictable that saliva will become contaminated with blood. If blood is not visible, it is still likely that very small quantities of blood are present, but the risk for transmitting HBV, HCV, or HIV is extremely small. Despite this small transmission risk, a qualified health care professional should evaluate any occupational exposure to saliva in dental settings, regardless of visible blood.
For more information on bloodborne pathogens in a healthcare setting, please take a look at OSHAcademy Course 656.
Hepatitis B Virus (HBV)
Health care workers who have received hepatitis B vaccine and have developed immunity to the virus are at virtually no risk for infection. For an unvaccinated person, the risk from a single needlestick or a cut exposure to HBV-infected blood ranges from 6%–30% and depends on the hepatitis B e antigen (HBeAg) status of the source individual. Individuals who are both hepatitis B surface antigen (HBsAg) positive and HBeAg positive have more virus in their blood and are more likely to transmit HBV.
Hepatitis C Virus (HCV)
Based on limited studies, the estimated risk for infection after a needlestick or cut exposure to HCV-infected blood is approximately 1.8%. The risk following a blood splash is unknown but is believed to be very small; however, HCV infection from such an exposure has been reported.
Human Immunodeficiency Virus (HIV)
Protection after Occupational Exposure
Wounds and skin sites that have been in contact with blood or body fluids should be washed with soap and water; mucous membranes should be flushed with water. Immediate evaluation must be performed by a qualified health care professional.
Health care providers who evaluate exposed dental health care professionals should be:
Occupationally related contact dermatitis can develop from frequent and repeated use of hand hygiene products, exposure to chemicals, and glove use. Contact dermatitis is classified as either irritant or allergic. Irritant contact dermatitis is common, non-allergic, and develops as dry, itchy, irritated areas on the skin around the area of contact.
By comparison, allergic contact dermatitis (type IV hypersensitivity) can result from exposure to accelerators and other chemicals used in the manufacture of rubber gloves as well as from exposure to other chemicals found in the dental practice setting. Allergic contact dermatitis often manifests as a rash beginning hours after contact and, like irritant dermatitis, is usually confined to the areas of contact.
Latex allergy (type I hypersensitivity to latex proteins) can be a more serious systemic allergic reaction. It usually begins within minutes of exposure but can sometimes occur hours later. It produces varied symptoms, which commonly include runny nose, sneezing, itchy eyes, scratchy throat, hives, and itchy burning sensations.
However, it can involve more severe symptoms include asthma marked by difficult breathing, coughing spells, and wheezing; cardiovascular and gastrointestinal ailments; and in rare cases, anaphylaxis and death.
Dental health care personnel who are allergic to latex will need to take precautions at work and outside the workplace since latex is used in a variety of other common products in addition to gloves.
If diagnosed with allergy to natural rubber latex (NRL) protein:
Dental personnel can further reduce occupational exposure to NRL protein by taking the following steps:
Proteins responsible for latex allergies are attached to glove powder. When powdered gloves are worn, more latex protein reaches the skin. Also, when gloves are put on or removed, particles of latex protein powder become aerosolized and can be inhaled, contacting mucous membranes. As a result, allergic dental health care personnel and patients can experience symptoms related to cutaneous, respiratory, and conjunctival exposure.
Dental health care personnel can become sensitized to latex proteins after repeated exposure. Work areas where only powder-free, low-allergen gloves are used show low or undetectable amounts of allergy-causing proteins.
Patients with a latex allergy should not have direct contact with latex-containing materials and should be treated in a "latex safe" environment. Such patients also may be allergic to the chemicals used in manufacturing natural rubber latex gloves, as well as to metals, plastics, or other materials used to provide dental care. By obtaining thorough patient health histories and preventing patients from having contact with potential allergens, dental health care professionals can minimize the possibility of patients having adverse reactions.
Considerations in providing safe treatment for patients with possible or documented latex allergy include (but are not limited to) the following:
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