Ergonomics: Health Implications for Dental Hygienists

Overview: Ergonomics and Health Implications for Dental Hygienists

Increase awareness Increase awareness Decrease work-related pain and injuriesDecrease work-related pain and injuries Heighten productivityHeighten productivity Improve musculoskeletal healthImprove musculoskeletal health Increase comfortIncrease comfort Improve quality of lifeImprove quality of life Extend careersExtend careers

What is Ergonomics?Ergonomics is the study of workers and their relationship with their occupational environment

How you position yourself, your patient, how equipment is utilized, how the workplace is designed and how it impacts your health

ERGONOMICS is a way to work smarter, more efficiently with less effort and discomfort to the human body

Ergonomics in the Dental Health FieldStudies show work-related Studies show work-related pain in the dental field is not pain in the dental field is not decreasingdecreasing

Over half of all dental Over half of all dental professionals continue to professionals continue to experience work-related experience work-related pain pain

Why?Why? The physically  The physically challenging nature of the challenging nature of the work with numerous work with numerous risk factorsrisk factors   

Risk FactorsProlonged Static PosturesRepetitive MovementsWorking in a confined spaceChallenges with positioning yourself or the patientLimitations with the tools and equipment used

©2008, Valachi from “Practice Dentistry Pain-Free”

Reasons for Early Retirement Among Dental Health Professionals

Musculoskeletal Disorders (29.5 %)Cardiovascular Disease (21.2%)Neurotic Symptoms (16.5%)Tumors (7.6%)Diseases of the Nervous System (6.1%)

©2008, Valachi from “Practice Dentistry Pain-Free”

Ergonomics: The Human Factor

People Are DifferentWe come in different shapes and sizes yet the workplace is often set up for “one size fits all”

People Have LimitationsWe have physical and mental limits for working

- The wrist cannot tolerate excessive extension

- The back cannot tolerate excessive bending or twisting

- The neck was not meant to be in constant flexion

- Muscles will fatigue if under constant tension

©2008, Valachi from “Practice Dentistry Pain-Free”

Consequences of Poor Ergonomics

FatiguePain/DiscomfortIllness/InjuryMissed days at workErrorsLower productivityPatient dissatisfaction

Poor Ergonomics: Signs and Symptoms

Physical SignsDecreased range of motion

Deformity

Decreased grip strength

Loss of muscle function

SymptomsPain

Numbness

Tingling

Burning

Cramping

Stiffness

©2008, Valachi from “Practice Dentistry Pain-Free”

Poor Ergonomics = Musculoskeletal Disorders

The World Health Organization definition: The World Health Organization definition: Musculoskeletal Disorder is “a disorder of the muscles,

tendons, peripheral nerves or vascular system not directly resulting from an acute trauma or instantaneous event”

Two Most Common Causes for Musculoskeletal Disorders in the Dental Health Profession

Cumulative Traumas Prolonged Static Postures

©2008, Valachi from “Practice Dentistry Pain-Free”

Cumulative Trauma Repetitive Movements like Scaling and Polishing are Cumulative Traumas

Vibrations transmitted by dental handpieces or mechanical scalers are Cumulative Traumas

Cumulative Traumas add up

These microtraumas cause “wear and tear” on the muscles, tendons, and nerve tissue

Prolonged Static Postures

Human body was designed for movement

Dental hygiene procedures means practitioners must maintain static postures

Hygienists hold postures that require more than 50% of the body’s muscles to contract to resist gravity

Muscle overload leads to decreased blood flow and increased pressure on the muscles and joints

©2008, Valachi from “Practice Dentistry Pain-Free”

Flowchart: Static Overload PROLONGED STATIC POSTURES

Muscle Fatigue and Muscle Imbalance

Muscle Ischemia, Trigger Points, Muscle Substitution

PAINProtective Muscle Contraction

Joint Hypomobility, Nerve Compression, Spinal Degeneration/Herniation

MUSCULSKELETAL DISORDERS

©2008, Valachi from “Practice Dentistry Pain-Free”

Static Postures leads to Muscular Imbalances

Muscles responsible for rotating the body to one side become tighter (shorter), while opposing muscles become weaker (longer)

Right handed hygienists repeatedly assume NECK ROTATION TO LEFT with SIDE-BENDING TO RIGHT to gain better visibility

Problems with NECK ROTATION TO RIGHT with SIDE-BENDING TO LEFT

©2008, Valachi from “Practice Dentistry Pain-Free”

Static Postures = Muscle Ischemia

As postures deviate from neutral, muscles contract harder to maintain working postures

During static muscle contraction, the vascular supply to muscle and surrounding tissues is restricted

Results in depleted nutrient and oxygen supply (ischemia)

Lactic acid and other metabolites accumulates causing pain and tissue damage

Cumulative Traumas and Prolonged Static Postures Lead to Musculoskeletal Disorders

Trigger Points and Myofascial Pain Disorders of Neck Degenerative Joint Disease (Arthritis)Thoracic Outlet SyndromeTendinitis

Carpal Tunnel Syndrome

Trigger FingerNerve Entrapment SyndromesLower Back PainSciatica

Myofascial Pain: Trigger PointsTrigger PointsTrigger Points: groups of muscle : groups of muscle fibers that are in a constant state fibers that are in a constant state of contraction inside a tight band of contraction inside a tight band of muscleof muscle

Feels like a knot or a small pea Feels like a knot or a small pea in muscles, and when pressed in muscles, and when pressed on can refer pain to distant parts on can refer pain to distant parts of the bodyof the body

Ischemic areas are susceptible Ischemic areas are susceptible to the development of trigger to the development of trigger pointspoints

Myofascial Pain: Trigger Points

Myofascial Pain: Trigger Points

Static Postures: Degenerative Joint Disease

Synovial fluid, which lubricates Synovial fluid, which lubricates the joints, is produced each the joints, is produced each time a joint movestime a joint moves

Lack of movement and Lack of movement and contracted muscles from static contracted muscles from static postures reduces the synovial postures reduces the synovial fluid production, resulting in fluid production, resulting in joint hypomobilityjoint hypomobility

This loss of mobility leads to This loss of mobility leads to degenerative changes and degenerative changes and more musculoskeletal more musculoskeletal disordersdisorders

Static Postures: Degenerative Joint Disease

SymptomsSymptoms

Intermittent/chronic pain Intermittent/chronic pain and stiffnessand stiffness

““Creaking” or “cracking” of Creaking” or “cracking” of jointsjoints

Swelling in the jointsSwelling in the joints

Loss of motion in the jointsLoss of motion in the joints

Increased pain with activity Increased pain with activity or useor use

Neck and Shoulder Disorders Thoracic Outlet Syndrome

Condition resulting from compression of the nerves, arteries, and veins as they pass through from the neck to the arm (thoracic outlet)

Possible causes: tight scalenes, cervical rib, tight pectoralis muscle, traumas

Often misdiagnosed

Neck and Shoulder Disorders Thoracic Outlet Syndrome

SymptomsPain in the neck, shoulder, arm or hand

Numbness and tingling of fingers

Muscle weakness/fatigue

Cold sensation in the arm, hand or fingers

Cumulative Trauma Injury: Tendinitis

When tendons slide back and forth through their sheaths friction is created

As with any other moving part, enough friction can cause wear and tear along with inflammation

When tendons or sheaths swell, and there is pain and tenderness

Wrist TendinitisPain, swelling and inflammation on the thumb side of the wrist

Made worse with grasping and twisting activities (polishing and scaling)

Occasional “catching” or snapping when moving thumb

Shoulder Tendinitis

Elevated arm postures cause shoulder impingement

Leads to tendinitis in the rotator cuff

Pain is usually felt in the front or the side of the shoulder

Worse with activity

Carpal Tunnel Syndrome

Compression of the Median Compression of the Median Nerve as it passes through Nerve as it passes through the Carpal Tunnelthe Carpal Tunnel

Caused by pinching and Caused by pinching and gripping activities with the gripping activities with the wrist bentwrist bent

Made worse with repetitive Made worse with repetitive flexion and extension flexion and extension activities at the wristsactivities at the wrists

Carpal Tunnel Syndrome

Symptoms “Pins and needles” in the hands and fingersPain in the thumb, index and middle fingerLimited range of motion at the wristPain radiating up the armDecreased grip strengthMore pain at night

Trigger Finger (Tenosynovitis)

Sustained forceful grips and repetitive motion irritates the tendon and tendon sheath (tenosynovium)

Nodules form in tendon causing warmth, swelling, tenderness of the tendon

Pain occurs during movement that place tendons in tension

Fingers lock in “Trigger Position”

Cubital Tunnel Syndrome

Prolonged use of the elbow while flexed or trauma from overuse can compress the Ulnar Nerve

Pain, numbness, tingling and impaired sensation in the little and ring fingers, side and back of hand

Loss of fine control

Reduced grip strength

Compression of ulnar nerve in Guyon’s canal at the base of the palm

Caused by repetitive wrist flexing or excessive pressure on palm/base of hand

Pain, weakness, numbness, tingling, burning in the little finger and part of the ring finger

Symptoms may worsen at night or early morning

Guyon’s Syndrome

Upper Crossed SyndromeTight Levator Scapulae

Upper Trapezius Scalenes

PectoralsWeak Middle/Lower Traps

Rhomboids Serratus Anterior

Deep Neck FlexorsElevated shoulders

Forward head postures

Jutting shoulder blades

Neck Pain and Upper Back Pain

Low Back Pain

Low Back Pain is the leading cause of occupational disability in the dental healthcare profession

Studies show that low back pain is clearly related to seated postures and sitting duration

Low Back Pain

We often think of a back injury as caused by a single event, like lifting a heavy load

The lower back is vulnerable to Cumulative Trauma

More lower back injuries result from the cumulative effects of bending, twisting, or excessive sitting

Working continuously in a seated position places tremendous static load on the back muscles, discs, and joints

Low Back Pain: The Problem with Sitting

With seated postures, pressure in the lumbar disks increases by 50% from standing

Unsupported sitting causes 2x more axial loading in the spine than standing

During forward flexion and rotation (a position often assumed by dental hygienists) the pressure increases by 200%

Low Back Pain: Disc Degeneration, Bulge and Herniation

Spinal discs provide for flexibility shock absorption

Discs are composed of tough outer layer (annulus fibrosis) and gel-like center (nucleus pulposis)

When weight is applied to the disc, the nucleus expands outward and puts pressure on the annulus fibrosis

Low Back Pain Disc Degeneration and Herniation

Sitting while flexing forward compresses the discs in the front

Uneven pressure on the disc leads to disc bulging and herniation

When the disc bulges or herniates backwards the nerves can become pinched

Low Back Pain: Sciatica

Pain from lower back or hip radiating to the buttocks and legsLeg weakness, numbness, or tinglingCommonly caused by prolapsed intervertebral disc pressuring the sciatic nerve Worsened with prolonged sitting or excessive bending and lifting

Low Back Pain: A Vicious Cycle

People with back problems seem to be faced with this vicious cycle

There is considerable evidence that bed rest and passive treatments have limited value

We now know that activity and the right kind of exercise are critical to treating back pain

Stop Moving

Back Pain Hurts to Move

Stiffness

Weakness

Lower Crossed Syndrome

Tight Hip Flexors Lower Back

MusclesWeak Abdominal Muscles Gluteus Maximus

Swayback - excessive curve of the lower back

Anterior Pelvic Tilt - hips tilted forward

Lower Back Pain

What is the best position to sit in?Traditional 90º Sitting Is not It

Problems with Traditional 90° SittingLooks nice but it’s just not comfortableNatural curve of the lower back collapsesLeads to muscle tension and misaligned vertebraeIncreases static load on the discsDecreases circulation in lower extremities

What is the best position to sit in?Leg Balanced Sitting

Allows for forward and upward postures to transfer some of the body’s support to the feet

Hip angle of 100 ° to 120°°

Knee angle of 110° to 135°

Forward seat tilt of 45° to 55° from horizontal

Opposing muscle groups are balanced and curve in lower back is maintained

Chair Selection

Saddle Seat Design

True waterfall design is an essential feature

Hydraulic piston assembly for the widest range of motion

Seat should be adjustable so hips can be slightly elevated beyond parallel without restricting blood flow to the legs

Ergonomics for Dental HygienistsWorkstation Layout

Clutter threatens the safety and cleanliness of the dental operatory

Allows convenient positioning when required

Provide a clear line of sight to the oral cavity and all required equipment

Ergonomics for Dental HygienistsWorkstation Layout

Optimize space for work from 7 o’clock to 1 o’clock position for right handed Hygienists (11° to 5° if Left Handed)Instruments should be accessible while seated (within 20 inches of the front of body)Hoses should be positioned away from the bodyOver-the-Patient or Over-the-Head equipment is most ergonomic

Use mobile carts for less commonly used Use mobile carts for less commonly used equipmentequipment

Ergonomics for Dental Hygienists Scheduling

Scheduling of procedures should be considered. Difficult procedures scheduled back-to-back does not allow your body sufficient relaxation timePotential strategies– Increase treatment time for more difficult patients– Alternate heavy and light calculus patients within a

schedule– Vary procedures within the same appointment– Shorten patient’s recall interval

Ergonomics for Dental HygienistsReduce Physical Effort

Avoid bent or unnatural posturesAvoid bent or unnatural postures

Minimize sustained effort

Brief but frequent rest pauses can minimize fatigue and enhance productivity

Incorporate different activities to shift musculoskeletal demands from one part of the body to another

Ergonomics for Dental Hygienists Equipment Equipment

If your air/water syringe has a tightly coiled cord, consider replacing it with a lightweight hose

Swiveling devices can be placed on a handpiece to reduce torque

Newer handpieces are much lighter than the older models

Ergonomics for Dental HygienistsHand InstrumentsHand Instruments

Look for:Hollow or resin handlesRound, textured grooves, and compressible handlesCarbon-steel constructionColor-coding may make instrument identification easier

Ergonomics for the Dental HygienistsMagnification Systems

Should improve neck postures and Provide clearer vision

Consider additional lighting

Weight should also be considered

Ergonomics for Dental HygienistsErgonomics for Dental HygienistsGlovesGloves

Gloves are one of the most Gloves are one of the most overlooked ergonomic itemsoverlooked ergonomic items

Hand-specific gloves allow the Hand-specific gloves allow the thumb to be in a more natural thumb to be in a more natural positionposition

Gloves should not be too tight Gloves should not be too tight across the palm or too across the palm or too constricting at the wristconstricting at the wrist

The finger length should be The finger length should be adequate to allow for adequate to allow for comfortable finger movementcomfortable finger movement

Preventing Ergonomic Injuries

MoveChange PositionThere is no one “correct” posture best for an entire working dayThe Human Body Needs Change and Mobility

Preventing Ergonomic Injuries

Taking frequent, shorter breaks is preferable to taking longer, fewer breaks

Change positions before painful symptoms arise

Remember to go back to neutral postures

Preventing Ergonomic InjuriesStretching Guidelines

Never stretch to the point of pain or discomfort

Do not bounce or use quick, jerky movements

Stretch should be performed every half hour

Suboccipital Muscles

Deep muscles at the base of the skull responsible for protraction, rotation, and tilting of the head

Suboccipitals become shortened with forward head postures

Common cause for headaches

Levator Scapulae

Primary function is to elevate the scapula

Also bends the neck to the side

Tightens up when carrying a bag with a strap or talking on the phone

Scalenes

Functions to stabilize the neck during lateral movements

Aids in inspiration

Becomes tight with awkward leaning positions while seated

Trapezius

Upper elevates the shoulders

Middle retracts the shoulder blades

Lower rotates the shoulder blade downwards

Becomes tight with elevated arm postures

Pectoralis Minor

Functions to draw the shoulder blade forward and downward

Tight in people with a rounded shoulder posture

Shortened pec minor is a possible cause for Thoracic Outlet Syndrome

Wrist Flexors/Extensors

Prime function is to flex and extend the wrist

“Tennis Elbow” is pain on the lateral side of elbow

“Golfer’s Elbow” is pain on the medial side of the elbow

Hamstrings

Main function is to bend the knee

Secondary role in extending the hip

Weak low back and glute muscles increases tightness in the hamstrings

Prolonged seated postures also causes tight hamstrings

Iliopsoas

Primary function is to flex the hip (bring thigh up towards the abdomen)

People with chronic lower back pain often have very tight hip flexors

Commonly shortened with prolonged seated postures

Piriformis

Main function is to externally rotate the hip/thigh

Shortened in people who sit for long periods of time

“Piriformis Syndrome” causes compression of the Sciatica nerve

Questions and Answers