Dental occupational hazards & Safety Practices in Dental Settings

Health and safety in the
dental health care facilities
Dr. Ghada Elmasuri

Introduction
 The safety of the health care system is defined by the National
Health Performance Committee as the avoidance or reduction to
acceptable limits of actual or potential harm from health care
management or the environment in which health care is
delivered.
 Dental workers are at risk to many workplace hazards, including,
pathogens, pharmaceuticals, ergonomic and psychological
hazards

Introduction to OSHA
 OSHA “Occupational Safety and Health Administration” is a
government agency within the US Department of Labor
created in 1970 by the Occupational Safety and Health Act,
responsible for worker safety and health protection by
developing specific standards to protect biological, chemical,
environmental, physical, and psychological workplace hazards
that may apply to dentistry.

OSHA's Mission
1. To assure safe and healthful working conditions for workers by
setting & enforcing standards and by providing training,
outreach, education and assistance.
2. Requires employers to implement programs to reduce workplace
safety and health hazards
3. Investigates workplace fatalities or catastrophic accidents
4. Enforces safety and health standards through workplace
inspections by compliance officers
5. Monitors job-related injuries and illnesses through required
record-keeping
6. Provides assistance, training, and other support programs to help
employers and workers

The Occupational Safety and Health Act 1984
aims to:
1. Promote and secure the safety and health of people at work;
2. Protect people at work from hazards;
3. Assist in securing a safe and hygienic working environment;
4. Eliminate, reduce and control hazards; encourage cooperation
and consultation between employers and employees;
5. Provide for the formulation of policies and for the co ordination
of the administration of laws relating to occupational safety and
health; and
6. Promote education and awareness of occupational safety and
health
Source: section 5, Occupational Safety and Health Act 1984

OSHA's Control
Duties of employers towards their employees
Engineering
Controls
Administrative
controls
Personal
Protective
Equipment
Training

Engineering Controls
 Engineering Controls: 1st defence line in employee protection,
directed at the source.
 Common engineering controls include:
• Elimination
• Substitution
• Local exhaust ventilation
• General ventilation (only appropriate for non toxic chemicals)
• Isolation/enclosed processes
• Proper chemical storage
• Facility design

Administrative controls
 Policies & procedures that establish;
• Codes of practice “practical information on how to achieve safety
and health standards at the workplace”.
• Staff placement, work schedules,
• Good housekeeping
• Labeling products containing any form of hazards
• Dental worker immunization policies and programs
• Medical screening and surveillance
• Workplace monitoring
• Information, instructions and training.

Administrative controls (cont)
 Training in biological hazards and controls should be provided to
all dental workers by;
1. Organising groups information
2. Audio visual aids;
3. Provision of written information;
4. Using graphics;
5. Access to computer based information through the Internet.
 Training records should be maintained.

Personal Protective Equipment (PPE)
 PPE - used in conjunction with other controls (engineering and
administrative) to provide additional protection to workers.
 PPE - designed to protect workers from infectious disease by
breaking the chain of infection at the “portal of entry or exit” of
the microorganisms.
 PPE as Gloves, gowns, eye protection and other protective
clothing.

Occupational Hazards Associated with
dentistry
Blood borne
pathogens
Nitrous
oxide
Amalgam
Radiation
MSDs
Psychological

Blood borne Pathogens
 Human T-lymphotrophic virus
Type 1
 Malaria
 Syphilis
 Babesiosis
 Brucellosis
 Leptospirosis
 Arboviral infections
 Relapsing fever
 Creutzfeldt-Jakob disease
 Viral hemorrhagic fever
 Pathogenic microorganisms that are carried in the bloodstream
or transmitted by Other Potentially Infectious Materials.
There are over 20 different blood borne pathogens

Blood borne Pathogens
 Of most concern are
 Human Immunodeficiency Virus (HIV)
 Hepatitis B Virus (HBV)
 Hepatitis C Virus (HCV)
 Both patients and dental health care personnel can be exposed to
pathogens through Contact with blood, oral and respiratory
secretions, and contaminated equipment.

Modes of Transmission in the dental
settings
 Direct; from contact with blood or body fluids of an infected
patient
 Indirect; from contact with a contaminated instrument or
surface
 Droplets; from splatter contact of mucosa of the eyes, nose, or
mouth
 Inhalation of airborne microorganisms
Patient Dentist
Patient Patient
Transmission can be ;

The Infectious Process
“Chain of Infection”
Break in skin integrity
 Needle sticks
 Cuts, scrapes & skin breaks
Mucous Membranes
 Splashes to eyes, nose & mouth
 IV drug use

OSHA’s Blood borne Pathogens standard
 Was developed by OSHA in 1992.
 OSHA’s Blood borne Pathogens standard (29 CFR 1910.1030)
prescribes safeguards to protect workers from exposure to
blood-borne pathogens in the workplace, that must be
available in every dental office and clinic.
 The standard requires an employer to protect employees from
exposure to blood and other potentially infectious materials
(OPIM) in the workplace and to provide recommended care if
such an exposure does occur.

Requirements of OSHA 1910.1030
1. Exposure determination
2. Exposure control plan
3. Annual awareness training
4. Implementation of engineering and work practice controls
5. Proper labeling of blood or other potentially infectious
materials
6. Free HBV vaccinations
7. Free medical evaluations for incidents of exposure

OSHA Exposure prevention strategies
 The goal of these strategies is to “break the chain” of infection
by practicing protocols that can prevent cross-contamination
from one host to another .
1. Engineering controls: refers to removing or isolating the
hazards
2. Work practice control: refers to reduce the exposure by
altering the manners of performing tasks.
3. Administrative control: through implementation of policies,
procedures and enforcement of measures.

ENGINEERING CONTROL
Sharps disposal containers
 “Needle stick Safety and Prevention Act” was passed by OSHA in
2000.
 Sharps disposal containers must be provided and used.
 It must be leak-proof, puncture resistant, able to be closed, and
labeled or color-coded.
 Hand washing facilities should be readily accessible or
appropriate antiseptic hand cleanser in conjunction with clean
paper towels or antiseptic towelettes if hand washing facilities is
not feasible.

 One hand needle recapping, and needle bending directly by fingers
should be avoided.
 Using instruments in stead of fingers to place disposable
contaminated sharps in an accessible sharps container.
 Washing hands immediately after removing gloves.

 Contaminated reusable sharps should be placed in
immediately after use in a puncture-resistant and labeled
containers until properly reprocessed.
 Eating, drinking, smoking, applying cosmetics or lip balm, and
handling contact lenses are prohibited in work areas where
there is a reasonable likelihood of occupational exposure.

 Appropriate sizes of personal protective equipment (PPE)
“provided at NO COST to the employee” must be used
and then removed prior to leaving a work area or upon
contamination.

Personal protective equipment
 Disposable Gloves shall be readily accessible, replaced as soon
whenever their ability to function as a barrier becomes compromised.
 Masks with eye protection devices, as goggles or glasses with solid
side shields, or chin-length face shields, shall be worn whenever
splashes, spray, spatter, or droplets of blood or OPIM may be
generated.

Work practice controls
Housekeeping
 Regulated waste must be placed in closeable, leak proof containers
built to contain all contents during handling, storing, transporting or
shipping and be appropriately labeled or color-coded.

Work practice controls
Housekeeping
 Sharps containers:
 must be located as close as is feasible to where sharps are used,
 must be maintained upright throughout use,
 must not be overfilled,
 must be closed prior to disposal.

Immunization & health surveillance
Hepatitis b vaccination
 The employer shall make available the Hepatitis B vaccine and
vaccination to all employees who have occupational exposure.
 Employees who decline the vaccination must sign a declination
form.
 A confidential medical evaluation and follow-up shall
immediately be made available to an employee following an
exposure incident. This must be offered at no cost to the
employee.
Paragraph (f)(3 – 5)

Medical Record keeping
 An accurate record should be established & maintained “for
duration of employment “plus 30 years” for each employee with
occupational exposure.
 Employee medical records must be kept confidential and not
disclosed or reported without the employee’s written consent
(unless required by law).
Paragraph (h)(1)

Medical Record keeping
 The record shall include :
(A) Name and social security no of employee;
(B) Employee Hepatitis B vaccination status;
(C) Results of examinations, medical testing, and post-exposure
evaluation and follow-up procedures;
(D) Healthcare Professional’s (HCP’s) written opinion;
(E) Copy of information provided to the HCP.
Paragraph (h)(1)

Information and training
 Occupational exposure training program must be provided at
no cost to the employee.
 The training shall be provided:
 At the time of initial assignment to tasks where occupational
exposure can occur;
 At least annually thereafter.
 Additional training shall be provided when tasks are modified
or new procedures affect the employee’s occupational
exposure.

Mercury exposure
“Dental Amalgam”
 Dental amalgams are metal alloys composed primarily of
mercury (42%-58%), silver (21%-40%), tin (5%-17%) and
copper (1%-16%). Mercury is the largest component in a
silver filling.
 Current scientific evidence supports dental amalgam as a
safe and effective dental filling.
 However, it represent a significant biological source of
environmental mercury. The OSHA maximum allowable
environmental level of 50 µg/day in the workplace.
 Exposure is through : inhalation of vapours, ingestion and
skin absorption. Skin sensitizer. Corrosive as liquid.

Health effects for dentists
 A study reported that 180 dentists had 4 times the urinary
mercury excretion levels of 180 people in a control group.
Dentists were also significantly more likely than control subjects
to have had disorders of the kidney or memory disturbance.
“Ritchie et al.,2002”
 A 2004 study also found a link between cognitive impairment
(including mood) and mercury exposed-dentist.
“Ritchie et al.,2004”
 A Norwegian study has documented a decline in cognitive
abilities of the studied dental professionals greater than the
non-mercury exposed individuals.
“Moen et al., 2008”

Environmental concerns
 The WHO reports that one-third of the mercury in the sewage
system comes from dental amalgam flushed down the drain.
 It is estimated that about half of the mercury released from
current and historical dental amalgam use remains potentially
bio available, making all individuals exposed to mercury pollution
to some degree.
 Economically this pollution is considered an external cost not
factored into the dental amalgam costs.
 Environmental mercury may enter the biosphere through
discharges into the atmosphere (by incineration as medical or
general solid waste or by the dental evacuation system) or
through discharges into the water.

Environmental concerns
 The European Commission reported dental amalgam as a
significant contributor to overall EU environmental emissions of
mercury. Mercury released to the air can be partly deposited in
to soil, water, vegetation making mercury emissions in the
environment more difficult to quantify.

Health and Environmental Concerns
Of Dental Amalgam
Mercury and mercury
compounds regulation
EP
A
OSHA FDA
1. The Environmental Protection Agency:
responsible for regulating mercury and
mercury compounds discharges into the
environment (atmosphere, waters and
landfills).
2. The Food and Drug Administration: for
regulating mercury levels in food, drugs,
cosmetics and medical devices.
3. The Occupational Safety and Health
Administration responsible for regulating
workplace mercury &worker exposure to
mercury and its compounds, both in industry
as well as in professional practices.

Mercury exposure control
1. Elimination of mercury containing equipment. Substitution
with less harmful product.
2. Mechanical amalgamators to ensure no physical contact.
3. P-Protective clothing, gloves, eye and face protection, and
respiratory protection based on hazard assessment.
4. Properly designed and maintained ventilation systems. Local
exhaust ventilation may be required.
5. Education of workers in the nature of the hazard.
6. Monitoring of the work environment.
7. Good hygiene practices.
8. Appropriate storage of products to decrease exposure.

Nitrous Oxide (N2O)
 Commonly called laughing gas, is exists as colourless,
nonexplosive, non-flammable gas at room temperature. The
gas promotes combustion similar to oxygen and has a slightly
sweet odour and taste.
 Is an anaesthetic agent Dental workers are exposed to Nitrous
Oxide (N2O) during administration of this anaesthetic gas to
patients.

NIOSH
 The National Institute for Occupational Safety and Health
(NIOSH) recommended a Time Weighted Average (TWA)
concentration of 50 ppm when N2O is used in dental offices,
and 25 ppm when it is used during anesthetic administration.

Overexposure health effects
Chronic
1. Irritability
2. Headache
3. Reduced fertility
4. Spontaneous abortion
5. Liver and kidney effect
6. Central nervous system effect
Acute
1. Dizziness
2. Headache
3. Nausea
4. Fatigue
5. Irritability
6. Decrease in visual acuity.

Source of overexposure
1. Poor scavenging system design
 Clinical evaluation of the 3 major scavenging system brands
“Accutron, Porter brown & Matrx indicated that Porter brown
is better performing compared to others.
Porter brown
Mask within a mask

1. Poor scavenging system design
Accutron and Matrx design: a single nasal hood with a connector
cap.
Matrx design
Accutron design

Missing damaged or poorly maintained
Hole in Supply Tubing Torn Reservoir Bag
Damaged scavenging components

Damaged cylinder head
Small metal section missing on
the cylinder head prohibiting
adequate seal

Sever discoloration indicates prolonged use
Worn components

Poor employee work practice
 Engaging patient in to unnecessary conversation during the
administration of N2O.
 Activating the flow of N2O before the mask is placed on the patient.
 Tightening the tube retention device to much on the patient.
 Failure to deploy exhaust

N2O exposure Controls
 The exposure limit recommended by NIOSH approximately 25
ppm during analgesia administration,
 NIOSH recommended 3methods of control:
1. System Maintenance
 Inspect and maintain the anaesthetic delivery system to
prevent N2O leaks in the worker's personal breathing zone,
connections, fittings. Repair all leaks immediately.
Qualitative test for leaks using water
and soap solution

2. Ventilation
 Control waste N2O with a well-designed scavenging system that
includes the following:
1. Securely fitting masks
2. N2O flow rates from the patient's mask should be maintained at
an air flow rate of 45 LPM and measured by a calibrated flow
device, and vented outdoors -- not into the room ventilation
system.
3. If concentrations of N2O are above 25
LPM, Increase the airflow into the room
and an auxiliary local ventilation
should be placed near the patient's
mouth to capture excess N2O from
breathing.

3. Work Practices
 Select scavenging masks of proper sizes to fit patients.
 Prudent use of N2O to appropriately sedate patients is
encouraged.
 Monitor the air concentration of N2O to insure Controls are
effective in achieving low levels during dental operations.

Employee training
1. All dentist, dental hygienist, assistants and technicians should
receive proper training on dealing with nitrous oxide.
2. how to properly secure the scavenging mask on patient
according to each manufacture
3. Avoid unnecessary conversation with the patient during N2O
administration.
4. When to deploy and when to terminate the administration of
N2O.
5. How to setup the scavenging unit`s exhaust system.
6. how to inspect the unit for any leak.
7. How to install multi use gasket when installing new cylinder.

X-ray radiation
 Dental radiography is one of the most valuable dental tools that
help to diagnosis physical conditions that would be difficult to
identify.
 X-radiation has the potential for damaging healthy cells and tissues
as well as carcinogenic and causing genetic changes.
 Dental practitioner who used to hold the dental X-ray films inside
the patient’s mouth (for obtaining better quality of image)are at risk
for developing radiation dermatitis on hands, or on a squamous cell
carcinoma of the figures.

Overexposure control
PPE
 OSHA Limits: Whole body limit = 1.25 -2 rem/qtr per year.
 Hands and feet limit = 18.75 rem/qtr.
 Skin of whole body limit = 7.5 rem/qtr.
 A range of PPE may be used to reduce radiation exposure as:
 Lead gloves, aprons, etc. as required.

Engineering control
1. The room containing the dental X-ray equipment should be
designed so that during the examination the operator is not
exposed to the primary radiation beam and can keep a distance of
at least 3 metres from the X-ray tube and from the patient or
2. An adequately shielded barrier, which allows observation of the
patient, must be provided for the operator to stand behind during
radiography.
3. Appropriate shielding materials, where necessary, for floor, walls,
ceiling and doors.
4. Equipment design to minimize scatter.
5. Replacement of older dental X-ray equipment with newer
equipment with additional safety features.

Administrative control
1. Worker education and training.
2. Safe work procedures reduce exposure time (procedures
requiring fewer workers in area, etc.).
3. Scheduling.
4. Radiation safety program.
5. Radiation exposure monitoring and regular checking of
leakage from X-ray machine should always be performed.
6. All ionizing radiation protective clothing must be uniquely
identified and inspected annually with an x-ray machine for
any sagging, cracks or holes in the shielding material.
7. These inspections results must be recorded and saved.

Ergonomic hazard
 Research has found, symptoms of discomfort for dental workers
occurred in the wrists/hands (69.5%), neck (68.5%), upper back
(67.4%), low back (56.8%) and shoulders (60.0%).
 Also 93% of those surveyed stated that they had at least one job-
related ache, pain, or discomfort in the 12 months prior to the
survey
(Anton, 2002)
 According to an evaluation from the Bureau of Labor Statistics
(2002), dental hygienists ranked first above all occupations in the
proportion of cases of carpal tunnel syndrome per 1,000
employees.

Back, Neck Disorders
Risk factors
 The pressure in the lumbar discs increases by 50% as compared to
standing.
 Sitting in an unsupported posture can cause twice the amount of
stress as compared to standing.
 During bending (forward flexion) and twisting (rotation) motions
of the spine, the pressure on the lumbar discs increases by 200%
(Fisk, 1987), causing compression on a spinal nerve.
 Inadequate work breaks.
 Repeated stresses from over the years begin to add up and slowly
cause degeneration of various parts of the spine, resulting in low
back pain.

Back, Neck Disorders
 Myofascial Pain Disorder (MPD)
 Possible causes : overloaded neck/shoulder muscles.
 Pain and tenderness in the neck, shoulder, arm
muscles, and a restricted range of motion.
 Cervical Spondylosis
 chronic neck and shoulder pain or stiffness, headaches,
hand and arm pain, numbness, tingling, and
clumsiness.
 Possible causes: time spent with the neck in sustained
awkward postures.
Shoulder
 Dropping

Hand and Wrist Disorders
Carpel tunnel syndrome
when the median nerve, which runs from the forearm
into the hand, becomes pressed or squeezed at the
wrist
caused by prolonged use of the elbow while flexed,
resting the elbow on an armrest.
It is characterized by pain, numbness, tingling and
impaired sensation in the little and ring fingers, side
and back of hand, and reduced grip strength.
Guyon’s syndrom
Ulnar nerve entrapmnet at the ulnar tunnel in the
wrist
characterized by pain, weakness, numbness,
tingling, burning in the little finger and part of the
ring finger.

Trigger Finger
sustained forceful grips and repetitive motion irritates
the tendon and tendon sheath causing warmth,
swelling, and tenderness of the tendon. Pain occurs
during movement that place tendons in tension. The
fingers lock in the “Trigger Position”.
Tendonitis of the Wrist
Prolonged grasping of light objects and twisting
activities (e.g. polishing and scaling) can reduce blood
flow and strain tendons, leading to tendonitis.
 pain, swelling and inflammation

Risk factors
 Risk factors
1. Repetitive movements of the hand and wrist
2. Abnormal or awkward positions of the wrist
3. Mechanical stresses to digital nerves such as sustained
grasps on instrument handles
4. Forceful work
5. Extended use of vibratory instruments
6. Inadequate work breaks
Source: USAF Dental Evaluation & Consultation

Applying Ergonomics to Dentistry
Workplace Intervention
 Currently there are no occupational safety and health (OSHA)
standards for ergonomic, only recommendations.
 Equipment used should be placed within comfortable reach
(within 20 inches of the front of the body).
 Use mobile carts for less commonly used equipment

Working Posture and Techniques
Scaling task performed with three different finger positions Source: Dong, 2005
Goal: avoid static and/or awkward positions Potential strategies
Position patient so that operator’s elbows are elevated no more
than 30 degrees.
Adjust patient chair when accessing different quadrants

Working Posture and Techniques
 Avoid bent or unnatural
postures.
 Alternate between standing
and sitting .
– DHCP should adjust equipment
to the appropriate height
– Position the patient to allow
easy access from the desired
position
– Brief but frequent rest pauses
can minimize fatigue and
enhance productivity.

Instrument Design
When selecting dental tools
– Overall shape/size
– Handle shape/size
– Weight
– Balance
– Ease of operation
– Ease of maintenance
When selecting hand pieces
– Lightweight, balanced
models
– Sufficient power
– Built-in light sources
– Angled vs. straight-shank
– Swivel mechanisms
– Easy activation
– Easy maintenance
Goal: reduce force exertion; maintain hand/wrist in neutral position

Magnification
 Through the use of such magnification systems dental practitioners
are able to maintain a neutral working posture while increasing their
visual acuity, level of motor control, and diagnostic ability (UBC,
2008).
 Goal: improve neck posture; provide clearer vision
 When selecting magnification systems consider
– Working distance
– Depth of field
– Power of magnification
– Lighting needs
– Adjustability of system
– Weight

Personal Protective Equipment
 Clothing
– Fit loosely, lightweight, pliable
 Gloves
Poor fitting gloves can cause pain in the hands, particularly at the
base of the thumb. This is often due to compression of the tissues
when gloves are either too small or too loose as “bunching” occurs.
 Be of proper size, lightweight, and pliable
 Should fit hands and fingers snugly
 Should not fit tightly across wrist/forearm

Lightening
Source: Optimal overhead light positioningSource: UBC, 2008
The goal of proper lighting is to produce even, shadow-free
illumination concentrated on the operating field. It serves to increase
visibility and can also reduce awkward working postures.
For optimal illumination
the light-line must be as
close to the sight-line as
possible. The greater the
deviation of the light-line
from the sight-line the
greater shadowing (UBC,
2008).

Operator Chair
 Goal: promote mobility and patient access; accommodate
different body sizes
 consideration:
– Stability
– Lumbar support
– Hands-free seat height adjustment
– Fully adjustable
 Researchers recommend that:
 a shorter clinician have a seat adjustment range from 16 to
21 inches, taller individuals have a range of 21 to 26 inches.
 Ideally, a clinician should be able to function from a height
range where their thighs are parallel with the floor and the
legs are in fully supported position (Sanders, 1997).

Patient Chair
 When seating a patient, optimal results will be achieved when their
oral cavity is positioned at a height equal to the seated height of
the clinician’s heart.
 Goal: promote patient comfort; maximize patient access
 consideration:
– Stability
– arm rests for the patient
– Fully adjustable head rest
– When patient is properly positioned your shoulders, elbows, and
wrists of the dentist should be in a neutral position, meaning
that:
– the upper arms are close to the body
– the dentist`s elbow / forearm angle is close to 90º
– the dentist`s wrists are in line with the forearm with no more
than 20-30º extension

Psychological hazards
 Stress: coping with difficult or uncooperative patients, over
workload, constant drive for technical perfection,
 underuse of skills and challenging environment are important
factors contributing to stress among dentist.
 Professional burnout: “A syndrome of emotional exhaustion,
depersonalization and reduced personal accomplishment.
 Anxiety disorder and Depression, are accompanied by intense
physical symptoms like feeling sweaty, weak, faint, dizzy, flushed
or chilled; having nausea, chest pain, smothering sensations, or a
tingly or numb feeling in the hands.
 GAD is characterized by chronic exaggerated worry and tension,
even though little or nothing has provoked it.

Coping Psychological hazards
 Management policies and procedures that support work-life balance
and procedures related to no tolerance of violence or abuse.
 Scheduling to avoid overwork load. Worker should be involved in
design of shift schedule.
 Training to increase awareness of signs and symptoms of critical
incident stress.
 Management policies and procedures that ensure no discrimination
between workers.
 Self education about stress cope and change strategies as healthy
lifestyles, adequate sleep, deep breathing exercises; Physical exercise,
relaxation; meditation , time management, communication.
 Stressors such as failing to meet personal expectations, seeing more
patients working quickly can be managed by breaking the large task
into small ones.

Health Hazards Associated with dental
Lab
Blood borne
pathogens
Beryllium
Chemical
hazards
Physical
hazards
Ergonomics

Health Hazards Associated with dental
Lab
Transmission
of infection
Bloodborne
pathogens
Dental laboratory
personnel are at risk of
acquiring infections
from dental prostheses
that have not been
properly disinfected.

Bloodborne pathogens control in the
dental lab
 Barrier system: it includes
• Hand washing with plain or antimicrobial soap.
• Use of personal protection equipment

dental lab
 American Dental Association (ADA) guidelines state that
impressions should be rinsed to remove saliva, blood and
debris and then disinfected before being sent to the
laboratory.
 Plastic disposable trays should be used
 All brushes, rag wheels and other laboratory tools should be
heat-sterilized or disinfected daily.
 Wet rag wheels should be stored in a disinfectant solution
 when not in use.
 The lathe machine should be cleaned and disinfected daily.

dental lab
 Disposables that can be considered “sharps” items (e.g.
wire, disposable blades, burs, etc.) should be disposed of in
appropriate containers designated as “sharps” disposable
containers.

Exposure to Beryllium in Dental
Laboratories
 Dental laboratory technicians that work with alloys containing
metals such as beryllium that is used for castings of bridge
framework and other dental prosthesis components are at risk for
developing beryllium sensitization and chronic beryllium disease.
 While the amount of beryllium used in dental alloys is small ‘’ 0.05
- 2%’’, there is still a risk of developing beryllium sensitization or
CBD through breathing the dust and fumes produced while
altering the alloys.

OSHA beryllium standard
 Current Federal OSHA standard
 Less than 2 µg/m3 as an 8-hour average
 Compliance with these levels may not prevent chronic
beryllium diseaseThere is no level that assures zero risk of
BeS or CBD.
 The International Agency for Research on Cancer (IARC)
classifies beryllium as a human carcinogen.
 The World Health Organization’s listed beryllium as a
"known human carcinogen.

Chronic Beryllium Disease
 Chronic Beryllium 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.
 CBD is a serious lung disease that can be disabling and even
fatal, it may develop within months after initial exposure to
beryllium or may have a very slow onset and not develop until
years after exposure to beryllium has occurred.
 It has been reported by OSHA among dental laboratory
personnel in the past and recent letter OSHA indicating that
these cases continue to occur.

79
Health Effects of Beryllium exposure
• Lungs
– Acute beryllium disease
– Lung cancer
– Beryllium sensitization
(BeS)
– Chronic beryllium disease
(CBD)
Skin
Breathing
Routes of Exposure Health Effects
Illustration by National Jewish Health

Health Effects of Beryllium exposure
1. Slow wound healing
2. Nodules
– Response to beryllium under
the skin
3. Allergic rash
– Beryllium salts
4. BeS
– Broken skin & cuts
– Rash
– Even unbroken skin may not be
a complete barrier
80
Photo by National Jewish
Health
Nodules
Skin Effects

Signs & symptoms of Chronic
Beryllium Disease
1. Unexplained dry cough;
2. Shortness of breath
3. Fatigue;
4. Weight loss or loss of appetite;
5. Fever; or night sweats.
 Because the disease may develop slowly over a period of many
years, workers may have the disease for a long time without
knowing it. The individuals with CBD, who do not have clinical
symptoms of disease are generally referred to as having
asymptomatic CBD, or subclinical CBD.

Beryllium Sensitization
 A sensitized worker is one who has developed an allergic type
reaction to beryllium through inhalation of beryllium dusts or fumes.
beryllium particles containing become lodged under the skin causing
skin lesions and may induce sensitization.
 Some workers may become sensitized within weeks or months of
exposure on the job, while others may not become sensitized until
after leaving a job.
 Can be detected through the use of a blood test called the BeLPT,
“Beryllium Lymphocyte Proliferation Test” that measures how
lymphocytes react to beryllium.
 It is currently estimated that individuals with beryllium sensitization,
but without CBD, have about a 10% chance per year of progressing to
CBD.

Beryllium Exposure Control
Engineering Controls
 To ensure that dental laboratory technicians exposures to
beryllium are maintained below the current OSHA PELs. The
following engineering controls are recommended:
1. Where possible, alloys that do not contain beryllium should
be substituted for beryllium-containing alloys in dental work;
2. All procedures related to casting, cutting, grinding, or
polishing beryllium-containing dental alloys should be
conducted using properly designed and installed local
exhaust ventilation;
3. Vacuum systems and local exhaust ventilation systems
should be equipped with high-efficiency particulate air
(HEPA) filters.

Work Practices control
 Gloves and arm sleeves to minimize skin exposure;
 To minimize take-home exposures, workplace protective
clothing or equipment dusts containing beryllium should not
taken outside or take it home for laundering . CBD cases have
been reported among family members of many beryllium-
exposed workers.
 Vacuum work clothing before removal (clothes must not be
cleaned by blowing or shaking) and place clothes in a covered
container at the end of the workshift.
 Food items, drinks, cosmetics, or tobacco products should be
avoided into the work area;

Training and Information
 Employees exposed to beryllium should be trained in and have
access to the following information;
1. Material Safety Data Sheets (MSDSs) for identification of
dental alloys that contain beryllium;
2. The seriousness of the lung disease (CBD) that may occur as a
result of exposure;
3. The signs and symptoms of CBD;
4. The potential for developing lung cancer as a result of
exposure;
5. The importance of avoiding skin contact with dust containing
beryllium;

Hazard Information Bulletin
 To inform about the risk of CBD to individuals involved in
casting, sprue cutting, grinding, polishing and finishing of
dental alloys containing beryllium.
 It also provides information on the ways in which beryllium
exposures can be reduced,
 and the type of medical surveillance procedures that can be
used to identify to identify beryllium-sensitized individuals or
those who may be in the early stages of CBD
 It also offers information on the types of engineering controls,
work practices, training, personal protective equipment and
housekeeping procedures that can be used to reduce
beryllium exposure.

workplace monitoring
 Monitor employee exposures to airborne beryllium
dust and fume, can be:
 Air samples
– Measure the amount of beryllium in air
– Estimate the amount a worker might inhale
into their lungs
– Different types of air samples:
• Personal samples
• Area samples
 Surface Samples
– Measure the amount of beryllium on a surface
87
Beryllium collected on filter
and tested by laboratory
Photo by National Jewish Health

Routine medical surveillance
 Beryllium medical surveillance
 Routine testing with the BeLPT for
beryllium sensitization
 Chest x-rays.
88
Photo by US Navy
available under public
domain from Wikimedia
Commons

Chemical hazards
 Dental technologist are exposed to various dusts and chemical
fumes, many of which are known carcinogens. The problem may be
compounded where the technologist works in a confined space
and in conditions of poor ventilation.
 it is well known that levels of indoor pollution can be 100 times
higher indoors than outdoors,

Chemical hazards
 Including solvents, mineral acids, gases and vapours released
during polymerisation, metal casting, and porcelain baking.
 Among many chemicals, several should be mentioned including
silica, butylene glycol, hexane, ethyl acetate, glutaraldehyde,
benzoyl peroxide, hydroquinone, oxides of titanium, iron, and
most importantly is :
 Methyl methacrylate (MMA)
 Also known as methyl methacrylate monomer (or just
‘monomer’). Used in making dentures and plates, it can be
absorbed into the body by inhalation, through the skin, and by
ingestion.

Chemical hazards
Methyl methacrylate (MMA)
 Over exposure may lead to development of persistent
olfactory disorders in dental laboratory workers.
 Methyl methacrylate was subject to control by the Control of
Substances Hazardous to Health (COSHH) regulations .
The long-term (8 hour) Workplace
Exposure Limit (WEL) of is 50 parts per
million (ppm)
 short-term exposure WEL is 100
ppm.

Chemical hazards
 Repeated and prolonged exposure may cause a wide range of
adverse health effects , such as irritation to skin, eyes, or
mucous membranes, allergic dermatitis, asthma, as well as
central and peripheral nervous system disorders (headache,
pain in the limbs, nausea, loss of appetite, fatigue, sleep
disturbances, neuropathy, loss of memory, etc).
 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 irritations.

Chemical hazards
Silicosis
Source: What Dental Technicians Need to Know
About Silicosis. NJDHSS.
Occupational exposure to respirable crystalline silica is associated
with Silicosis which is serious but preventable pulmonary diseases
caused by inhalation of free crystalline silica (silicon dioxide).
Silica (silicon dioxide) is the most abundant mineral on earth. It
occurs in a crystalline or noncrystalline (amorphous) form.
 Dental lab materials that contain silica
1. sand
2. investment materials
3. porcelain
4. shop dust

Permissible exposure limit
 The current OSHA standards for noncrystalline (amorphous)
form is 20 million particles per cubic foot of air avarged over 8
hours work shift.
 NIOSH has recommended a permissible exposure limit of 50
micrograms (50 μg/m3—or 0.05 mg/m3) respirable free silica
per cubic meter of air averaged over a work shift of up to 10
hours.
 Routes of over exposure
 Inhalation
 Silica dust coming in contact with eyes

Dental Lab tasks causing Silica
exposure
1. Casting: exposure can occur when mixing
investment materials and during breaking of
castings. Investment materials contains 20-
70% of cristobalite that is a very toxic form of
crystalline silica.
2. Sandblasting of castings: by exposure to
the Silica sand that is used to clean castings.
Exposure also occur when the blasting box has
leaks. Or by opening the blasting box door
before the dust has settled or been removed.

Dental Lab tasks causing Silica exposure
• Grinding porcelain: Exposure can occur when mixing porcelain
powders or when grinding or polishing dried porcelain
material.

Dental Lab tasks causing Silica
exposure
 Cleaning/Maintenance: Tasks that involve cleaning
dusts that contain silica and when maintaining local
exhaust ventilation or dust collection systems.

Health Effects of
over exposure
 Acute silicosis: follows a large exposure to dust
Symptoms
1. cough,
2. shortness of breath,
3. Pleuritic pain; may develop in days to several weeks.
4. Followed by weight loss and fatigue in months to years.

Health Effects of over exposure
 Chronic silicosis: can be
1. Simple silicosis : Symptoms often appear in 1-3 decades after
initial exposure.
• Patients may be asymptomatic
• or present with exertional dyspnea and cough with sputum
production.
2. Complicated silicosis “progressive massive fibrosis”; symptoms
develop within 10 years after initial exposure.
• A distinction between simple and complicated chronic silicosis
is based on the chest radiographic appearance

Silica exposure control in a dental Lab
Engineering Control of Dust
1. Substitution of materials containing crystalline silica.
Aluminum oxide is an acceptable substitutes for
sandblasting media.
2. Ventilation: when there are no good substitutes, dust
exposure should be minimized through the use of local
exhaust ventilation systems that capture dust at its
source and transport it to a dust collection system.

work practice control
1. Using personal protective equipment: The worker should wear
a respirator when other control methods are missing or do
not work. The type of respirator recommended is, at a
minimum, a half-mask air-purifying respirator with type N-
100 particulate filters.
2. Good housekeeping– Wet wiping, wet moping, and
vacuuming with a HEPA vacuum are recommended. Dry
sweeping, dry dusting, use of com-pressed air, and use of
ordinary vacuum cleaners should be avoided because they
reintroduce the dust into the air.

 Dental technicians should be trained in the hazards of crystalline
silica exposure and the methods to control exposure
 Good housekeeping– Wet wiping, wet moping, and vacuuming
 Labeling products containing silica
 Medical screening

Physical hazards
 The noise in the dental labs is mostly caused
by grinding, cutting, sandblasting, polishing
operations and other dental lab machinery
can make noise that may cause hearing loss.
 It is discontinuous and wide‐band, but often
with predomination of high frequencies.
 During cutting and grinding metal surfaces
and plaster casts, the noise approaches and
exceeds the levels for harmful noise up to
92 dB(A), according to the measurements performed by
the Institute of Occupational Health.

Physical hazards
 During the work with metal and porcelain furnaces, dental
technicians are intermittently exposed to heat.
 long term exposure may result in “white finger syndrome”.
 Dental technicians are exposed to hand/arm vibrations while
working with various appliances and tools.

Ergonomics
 Musculoskeletal problems was reported as the most common
complaints among technicians “Jacobsen et.,al 1996”.
 Sitting posture during work, with precise manual handling of small
objects, may lead to back pain and strains of the musculoskeletal
system.
 Prolonged visual efforts due to inspection and shaping of small
pieces, often using magnifying lenses, result in eyestrain.

General Measures
1. Toxic, irritant, and sensitising materials should be
replaced by less harmful alternatives, where possible.
2. Adequate general and local ventilation systems must be
properly constructed in dental laboratories to prevent
respiratory and skin exposure to airborne contaminants.
3. Protective clothing should be made available and worn,
including eye and respiratory protection, and gloves. Properly
selected gloves are of vital importance among control
measures.

General Measures
4. Hearing protection must be worn during critical operations, when
the noise reaches the harmful levels—that is, 80 dB(A) and above.
5. Eating, drinking, and smoking should be prohibited in workplaces.
6. Job rotation can be used to reduce the exposure time while
working with vibrational tools.
7. Regularly undergo specific medical examinations

Conclusion
 Although not frequently reported, dental professionals may be
at risk for exposure to numerous occupational health hazards
wither in the dental clinic or during manufacturing dental
prostheses in the dental labratory. there is an ever growing
need for occupational health practitioners to be aware of the
work processes in this occupation, to recognise possible
hazards, and to implement specific measures to control and
reduce hazards associated with their occupations.

Recommendation
 Compliance to OSHA standards.
 Further studies are needed to evaluate the occupational
carcinogenic risk of exposure to a variety of chemical agents
used in dental technology.
 Introduction of new dental materials that is free of hazards
 Air filtration system designed to capture and retain exactly
those kinds of carcinogenic chemicals found in the dental
laboratory.

PPT-056-01 53
Guidebook for Health Care Professionals

References
 Aspden P, Corrigan J, Wolcott J, et al., editors. Patient safety: achieving a new
standard for care. Washington, DC: National Academies Press; 2004.
 Kotloff RM, Richman PS, Greenacre JK and Rossman MD. "Chronic beryllium
disease in a dental laboratory technician." Am Rev Respir Dis 147:205-207,
1993.
 Muller-Quernheim J, Zissel G, Schopf R, Vollmer E and Schlaak M. "
Differential diagnosis of berylliosis/sarcoidosis in a dental technician." Dtsch
Med Wschr 121:1462-1466, 1996. [Ger].
 Brancaleone P, Weynand B, DeVuyst P, Stanescu D and Pieters T. "Lung
granulomatosis in a dental technician." Am J Indust Med 34:628-631, 1998.
 Newman L, "Beryllium exposure and chronic beryllium disease caused from
working with dental alloys." Letter to Charles Jeffress, Assistant Secretary,
OSHA, dated January 3, 2001.
 Kelleher PC, Martyny, JW, Mroz MM, Maier LA, Ruttenber AJ, Young DA and
Newman LS. "Beryllium particulate exposure and disease relations in a
beryllium machining plant." J Occup Environ Med 43: 238-249, 2001.
 Newman LS, Mroz MM, Maier LA, Daniloff EM and Balkisson R. "Efficacy of
serial medical surveillance in a beryllium machining plant." J Occup Environ
Med 43: 231-237, 2001.

References
 McInerney JR, Beryllium health surveillance. "Presented at US Department of
Energy Chronic Beryllium Disease Prevention Program (CBDPP) Rule
Implementation Workshop, March 6-8," Washington, DC, 28 slides.
 Cotes JE, Gilson JC, McKerrow CB and Oldham PD. "A long-term follow-up of
workers exposed to beryllium." Br J Indust Med 40: 13-21, 1983.
 Cullen MR, Kominsky JR, Rossman MD, Cherniak MG, Rankin JA, Balmes JR,
Kern JA, Daniele RP, Palmer L, Naegel GP, McManus K and Cruz R. "Chronic
beryllium disease in a precious metal refinery." Am Rev Resp Dis 135: 201-208,
1987.
 Henneberger PK, Cumro D, Deubner DD, Kent MS, McCawley M and Kreiss K.
" Beryllium sensitization and disease among long-term and short-term workers in
a beryllium ceramics plant." Int Arch Occup Environ Health 74:167-176, 2001.
 Kreiss K, Mroz MM, Newman LS, Martyny J and Zhen B. "Machining risk of
beryllium disease and sensitization with median exposures below 2 ug/m3." Am J
Indust Med 30: 16-25, 1996.
 Stange AW, Hilmas DE, Furman FJ and Gatliffe TR. "Beryllium sensitization and
chronic beryllium disease at a former nuclear weapons facility." Appl Occup
Environ Hyg 16:405-417, 2001.
 Balkissoon RC and Newman LS. "Beryllium copper alloy (2%) causes chronic
beryllium disease." J Occup Environ Med 41: 304-308, 1999.

References
 Cotes JE, Gilson JC, McKerrow CB and Oldham PD. "A long-term follow-up of
workers exposed to beryllium." Br J Indust Med 40: 13-21, 1983.
 Cullen MR, Kominsky JR, Rossman MD, Cherniak MG, Rankin JA, Balmes JR,
Kern JA, Daniele RP, Palmer L, Naegel GP, McManus K and Cruz R. "Chronic
beryllium disease in a precious metal refinery." Am Rev Resp Dis 135: 201-208,
1987.
 Henneberger PK, Cumro D, Deubner DD, Kent MS, McCawley M and Kreiss K.
" Beryllium sensitization and disease among long-term and short-term workers in
a beryllium ceramics plant." Int Arch Occup Environ Health 74:167-176, 2001.
 Kreiss K, Mroz MM, Newman LS, Martyny J and Zhen B. "Machining risk of
beryllium disease and sensitization with median exposures below 2 ug/m3." Am J
Indust Med 30: 16-25, 1996.
 Stange AW, Hilmas DE, Furman FJ and Gatliffe TR. "Beryllium sensitization
and chronic beryllium disease at a former nuclear weapons facility." Appl Occup
Environ Hyg 16:405-417, 2001. Balkissoon RC and Newman LS. "Beryllium
copper alloy (2%) causes chronic beryllium disease." J Occup Environ Med 41:
304-308, 1999.
 Deubner DC, Goodman M and Iannuzzi J. "Variability, predictive value, and
uses of the beryllium blood lymphocyte proliferation test (BLPT): Preliminary

References
 Kreiss K, Newman LS, Mroz MM and Campbell PA. "Screening blood test
identifiessubclinical beryllium disease." J Occup Med 31: 603-608, 1989.
 Kreiss K, Wasserman S, Mroz MM and Newman LS. "Beryllium disease
screening in the ceramics industry: Blood test performance and exposure-
disease relations." J Occup Med 35: 267-274, 1993.
 Kreiss K, Mroz MM, Zhen B, Martyny JW and Newman LS. "Epidemiology of
beryllium sensitization and disease in nuclear workers." Am Rev Respir Dis
148: 985-991, 1993. Kreiss K, Mroz MM, Zhen B. Wiederman H and Barna B.
"Risks of beryllium disease related to work processes at a metal, alloy and
oxide production plant." J Occup Environ Med 54: 605-612, 1997.
 Ritchie, KA; Gilmour, WH; MacDonald, EB; Burke, FJ; McGowan, DA; Dale,
IM; Hammersley, R; Hamilton, RM et al. (2002). "Health and
neuropsychological functioning of dentists exposed to mercury". Occupational
and Environmental Medicine 59 (5): 287–93.
 BE Moen, BE Hollund, and T Riise, Neurological symptoms among dental
assistants: a cross-sectional study, J Occup Med Toxicol. 2008; 3: 10. Published
online 2008 May 18. doi:10.1186/1745-6673-3-10.
assistants: a cross-sectional study, J Occup Med Toxicol. 2008; 3: 10. Published
online 2008 May 18. doi:10.1186/1745-6673-3-10.

References
assistants: a cross-sectional study, J Occup Med Toxicol. 2008; 3: 10.
Published online 2008 May 18. doi:10.1186/1745-6673-3-10.
 WHO. (2005).Mercury in Health Care ^ Jump up to: MCMANUS, KEVIN
R.; F, P (2003). "Purchasing, installing and operating dental amalgam
separators: Practical issues". The Journal of the American Dental Association
134 (8): 1054–65. PMID 12956345.
 The European Commission ;Final report, July 11, 2012 (PDF)
• Bylund S H, Burstrom L, Knutsson A. A descriptive study of women injured
by hand‐arm vibration. Ann Occup Hyg 2002. 46299–307.307. [PubMed].
• Jacobsen N, Derand T, Hensten‐Pettersen A. Profile of work‐related health
complaints among Swedish dental laboratory technicians. Community Dent
Oral Epidemiol 1996. 24138–144.144. [PubMed].
• Nakladalova M, Fialova J, Korycanova H. et al State of health in dental
technicians with regard to vibration exposure and overload of upper
extremities. Cent Eur J Public Health 1995. 3(suppl)129–131.131. [PubMed].

Dental occupational hazards & Safety Practices in Dental Settings

Recommandé

Recommandé

Contenu connexe

Tendances

Tendances (20)

Similaire à Dental occupational hazards & Safety Practices in Dental Settings

Similaire à Dental occupational hazards & Safety Practices in Dental Settings (20)

Plus de Ghada Elmasuri

Plus de Ghada Elmasuri (7)

Dernier

Dernier (20)

Dental occupational hazards & Safety Practices in Dental Settings