Ergonomics Flashcards
ergonomics
the science of fitting hobs to the people who work them
goals of ergonomics (4)
❖Prevent work-related musculoskeletal disorders (MSDs)
❖Increase safety and productivity
❖Enhance performance by eliminating unnecessary effort
❖Improve the standard of care to the patient
In a University of CA-SF questionnaire, responses indicated that –% of the dental students from all four years experienced neck, shoulder and/or back pain. More than –% reported pain by their 3rd year.
46-71%
70%
when you are slouched over, why are you not able to fully breath out?
your lungs and internal organs are being compressed
musculoskeletal disorders (MSD)
include a group of conditions that involve nerves, tendons, muscles, and supporting structures such as intervertebral discs
contributing factors for work related MSDs include routine exposure to (4)
forceful hand exertions
repetitive movements
fixed or awkward postures
vibrating tools
what is the main cause of MSD in dentistry?
cumulative trauma disorders (CTDs) are theorized to be the primary cause of disability among dentists and best describes how injuries develop in dentistry
in dentistry cumulative trauma disorders begin as
microtrauma
microscopic damage that occurs to certain parts of your MS system on a daily basis
your body is constantly repairing this damage when you’re at rest
microtrauma occurs on the
cellular level, with the damage accumulative
the rate of damage to your body accumulates faster than the repair rate
do you often feel any discomfort before enough tissue damage occurs to create pain and muscle dysfunction?
no
warning signs (6)
Decreased strength (ex: instrument gripping)
Decreased range of motion (ex: turning head)
Pain or burning sensations
Numbness or tingling
Shooting or stabbing pain (usually into an arm or leg)
Swelling or inflammation
chronic low back pain (2)
often caused by a poor seated posture and weak stabilizing trunk muscles.
tension neck syndrome
common result of a forward head posture
trapezius myalgia
pain, tenderness from sustained contraction in upper trapezius muscle. Often from chronic elevation of the shoulders
rotor cuff impingement
houlder pain from over reaching, and a sustained arm elevation
carpal tunnel sundorme
medial nerve compression in the wrist from a flexed wrist posture, a forceful grip and/or gripping instruments with small diameters.
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dental ergonomic stressors (7)
- Sustained/awkward postures
- Repetitive tasks
- Forceful hand exertions
- Vibrating operational devices
- Time pressure from a fixed schedule
- Coping with patient anxieties
- Precision required with work
dental ergonomic equipment (4)
operator stools
patient chairs
magnification/loupes
lighting systems
3 Ps to fitness in the operatory
posture
positioning
periodic stretching
posture: maintain a
neutral position
posture (7)
❖Head at 0-20 tilt-ears over shoulders❖Shoulders over hips❖Elbows relaxed at sides❖Forearms parallel to the floor or slightly upward❖Slight curve in lower back/lordosis❖Hip angle >90-ideally 105-125*❖Feet flat on floor in tripod position
neutral seated position (5)
❖Forearms parallel to the floor ❖Weight evenly balanced ❖Hips higher than knees-110 degrees ❖Seat height positioned low enough so that you are able to rest the heels of your feet on the floor ❖Have a tripod effect-legs and torso
neutral neck position (2)
❖Head tilt of 0°to 15°.
❖The line from eyes to the treatment area should be as near to vertical as possible.
in neutral neck position, avoid (2)
head tipped too far forward
head tilted to one side
The head weighs 8-10 pounds, and for every one inch the head tilts forward, the load on neck and muscles —. Studies have shown that the greater the forward head position, the more likely people are to experience neck or shoulder pain or chronic tension headaches.
doubles
neutral shoulder position (2)
shoulders in a horizontal line
weight evenly balanced when seated
in neutral shoulder position, avoid (3)
shoulders lifted up toward ears
shoulders hunched forward
sitting with weight on one hip
neutral back position (2)
leaning forward slightly from the waist or hips
trunk flexion of 0-20 degrees
in neutral back position, avoid
over flexion of the spine (curved back)
neutral upper arm position (2)
upper arms hand parallel to the long axis of torso
elbows at waist level held slightly away from the body
in neutral upper arm position, avoid (2)
greater than 20 degrees of elbow abduction away from the body
elbows held above waist level
neutral forearm position (2)
parallel to floor
raised or lowered, if necessary, but pivoting at the elbow joint
in neutral forearm position, avoid
angle between the forearm nd upper arm of less than 60 degrees
establishing neutral position in relation to the patient (3)
- Adjust the height of the clinician chair to establish a hip angle of 110°.
- Lower the patient chair until the patient’s mouth is at the level of clinician’s heart.
- Elbow angle should be at 90°when clinician’s fingers are touching the teeth in the treatment area.
patient positioning to maintain neutral position (6)
Recline the patient: supine for maxillary, semi-supine for mandibular
❖Adjust headrest
❖Adjust chair height to maintain neutral position
❖Ask patient to move head as needed
❖Equipment placement within easy reach
❖Light position to avoid shadowing
rule of thumb (2)
when working on the mandibular, position the mandible ..
when working on the maxillary, position the maxilla ..
mandible parallel to the floor
maxilla perpendicular to the floor
operator positioning (5)
❖Establish line of sight for direct or indirect vision perpendicular to working surface
❖Operator position described as clock positions: predominantly 8-12 for right-handed operator, 1-4 for left-handed operator
❖Indirect vision with mirror
❖Change position frequently
❖Don’t side sit
position for right handed (4) 8 9 10-11 12
8: to the front of the patients head
9: to the side of the patients head
10-11: near the corner of the patients headrest
12: behind the patients head
position for left handed (4) 4 3 2-1 12
4: to the front of the patients head
3: to the side of the patients head
2-1: near the corner of the patients headrest
12: behind the patients head
periodic stretching (2)
chair side stretching
microbreaks to allow repair of micro traumas
in dentistry, rest breaks are usually done — and if done, —
infrequent
insufficient
hand clenching benefits the
hands and fingers
hand clenching:
Either sitting or standing, extend arms up parallel in front of you with palms facing each other. Inhale as you extend fingers wide. Exhale making fists with your hands and thumbs tucked in. Repeat 5 times then release.
wrist bending benefits the
hands and wrists
wrist bending:
Extend the arms out parallel in front of you. Inhale as you point your fingers upward toward the ceiling. Exhale as you point your fingers toward the floor. Repeat 5 times then release.
shoulder rolls benefits (3)
shoulders, upper back, and chest
shoulder rolls:
Inhale as you bring shoulders up toward ears. Exhale moving shoulders away from ears and down the back. Repeat 5 times and release.
wing and prayer benefits
shoulders supper back and chest
wing and prayer:
Bring hands together at heart in a prayer position.Inhale as you move palms away from each other while moving the shoulder blades close together behind back. Exhale as you bring hands back together in prayer position. Repeat 5 times and release.
daily physical activity such as sports, yoga, and pilates can activate
unused muscles or stretch out tightened muscles and makes you smarter
Exercise or physical activity of all kinds stimulates — (the process by which new neurons are formed in the brain), partly due to the production of Brain-Derived Neurotrophic Factor or BDNF (“fertilizer” for the brain that helps to maintain brain cells and grow new ones
neurogenesis
A study published in Neuroscience found that just 1— of rat cardio on the wheel resulted in a 171% increase in the amount of BDNF in the rodents brains!
week
HIIT (high intensity interval training) (5)
❖20-30 minutes of effort
❖Increase the intensity of cardio and do it in intervals
❖Increase intensity for 1-3 minutes, then come back to moderate intensity/active recovery for 2 minutes
❖Continue rotation for 20-30 minutes
❖Anything goes-walk, run, dance, row, etc
benefits to magnification (4)
❖Reduce strain on your eyes
❖Improve the quality of care and diagnostics
❖Improve your vision via greater magnification
❖Increased comfort via proper ergonomics
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7 important factors of surgical magnification
working distance
depth of field
declination angle
degree of magnification
co-axial alignment
flip-up capability vs TTL (through the lens)
learning curve for using surgical magnification
working distance: definition
The mean distance between the operator’s eye and the working site (patient’s oral cavity)
how can we estimate the working distance?
The loupe vendormeasures individually your nearest working distance and your furthest working distance. From this can be calculated your mean WD.
depth of field: definition
Range over which the operator is able to achieve visual resolution (discrimination).In other words, the ability to focus on both near and far objects without changing position
how can we estimate depth of field?
is it determined by the combination of individual vision and surgical magnification
declination angle: definition
the angle that you eyes are inclined downward toward the work area
declination angle range
10-20 degrees
manufacturers arbitrarily set the DA between
10-22 degrees
incorrect declination angle will cause the dentist to
adjust the head upward or downward which is not correct or safe, risk of neck or back strain
to maintain the most neutral head position, it may be a good idea to request the
steepest declination angle possible
degree of magnification
for most dental procedures magnification 2x to 3.5x; generally start with lower magnification
current recommendation is to start with
3.5x
when magnification is increased,
depth of field is decreased
difficulty with stabilizing the
field of vision
check that the surgical telescope (loupe) oculars are in — alignment
co-axial
what is co-axial viewing?
having a common axis
pencil picture
types of loupes (2)
adjustable flip-up telescope
through the lens (TTL) custom made telescope
advantages to flip up telescopes (3)
- Can be flipped up for unmagnified appraisals of field of view
- Declination angle can be adjusted
- Dentists who alter their positionscan adjust the declination angle as needed
disadvantages to flip up telescopes (3)
- risk of contamination during frequent adjustment
- associated with larger scotoma(blind spot)
- heavier and bulkier
advantages to through the lens (TTL) (3)
always in the correct position for viewing surgical field
wider field of view
lighter in weight
disadvantages to through the lens (TTL) (4)
are not adjustable for extraordinary procedures
higher costs
any change of prescription requires to return to the manufacturer
frame which support through the lens systems are heavier
learning curve
Most clinicians report that they achieve a basic familiarity and comfort after 10 days of use, but totaladaptationmay require as much as 2 months of full-time use.
Re-Check several times that the surgical loupes are correctly supporting all aspects of your
self-derived optimal control position
address subjective concerns such as (3)
weight
stability
physical comfort
there is a significant improvement in visual acuity when using magnification in conjunction with a
fiber optic light source
dental noises hover over the — to – decibel range
60-99
by comparison, motorcycles and dirt bikes are in the – to – decibel range
80-110
recent studies concluded that hearing impairment is greater in dental professionals and showed a correlation between the years of experience and increased
hearing impairment
ADA recommendations (4)
❖Wear ear plugs or noise-cancelling headphones while using dental equipment
❖When selecting dental equipment, consider its noise level
❖Have hearing tested to establish a baseline
❖Monitor your hearing acuity on a regular basis
types of noise inducing hearing loss (3)
acoustic trauma
temporary threshold shift
permanent threshold shift
Acoustic trauma
few exposures, intense sound level; ex: explosion
Temporary threshold shift
temporary hearing change following exposure to noise; ex: concert
Permanent threshold shift
result of accumulation of exposure to noise repeated over years; irreversible
which one do we experience in dentistry?
permanent threshold shift
One survey found that a significant number of dentists reported having
tinnitus
As many as 90 percent of people who experience tinnitus have had some
noise-induced hearing loss
tinnitus is often the precipitating cause for an individual to pursue a
hearing evaluation
steps to start protecting your hearing (2)
❖Visit ENT/audiologist for a baseline hearing test.
❖Choose hearing protection to suit your needs and use it!
