Dental Ergonomics: Optimizing Work Environment

Introduction

• Dental professionals face material and temporal constraints, leading to physical and nervous tension and impacting work efficiency and overall health.
• Health is described as the balance between the mental, emotional/spiritual, and physical aspects.

Ergonomics

• Ergonomics is derived from the Greek words "ergon" (work) and "nomos" (law).
• The French Ergonomics Society (SELF) defined ergonomics in 1969 as the scientific study of the relationship between humans, their resources, methods, and work environments.
• Ergonomics focuses on improving the adaptation of humans to technological production and living environments.
• Ergonomics aims to maximize comfort, safety, and efficiency.

Ergonomics Objectives based on GRANDJEAN, 1983

• Adjust work demands to fit human capabilities to reduce constraints.
• Design machines, equipment, and installations that maximize effectiveness, accuracy, and safety.
• Carefully study workstation setups and working conditions to ensure proper posture.
• Adapt the environment (lighting, air conditioning, noise) to human physical needs.

Benefits of Ergonomics

• Improves work postures and environment
• Enhances comfort and the operator's work context
• Boosts operator effectiveness and care efficiency
• Reduces the risk of work-related diseases
• Minimizes physical and nervous fatigue to match human capabilities
• Supports both worker productivity and quality of life

Consequences of Dental Practice on Health

• Conventional dental treatments involve dentists bending over patients, leading to unnatural postures with negative health impacts.
• These postures can cause serious physical disorders and repeated micro-trauma.
• A dentist's exposure includes musculoskeletal disorders, cardiovascular diseases, vision problems, hearing issues, stress, and nervous tension.
• A confined and darkened oral cavity needing intense concentration creates exposure risks.

Musculoskeletal Disorders (TMS)

• TMS involves chronic pain in supporting structures (muscles, nerves, tendons, joints, cartilage) in the upper and lower limbs, often leading to sick leave or early retirement.
• TMS stems from a mix of biomechanical (repetitive motions, effort, posture) and psychosocial factors related to work organization.
• TMS primarily affects the muscles, tendons, and joint articulations of the limbs and trunk.
• TMS is initiated by arthrosis of the dorso-lumbar spine, lower back pain, herniated discs, and scoliosis.
• TMS results in pain, stiffness, loss of strength, and clumsiness, affecting well-being and impacting work quality.
• Pain prevalence among dentists is high, ranging from 64% to 93% across all sites, with the lumbar region (36.3% to 60.1%) and cervical region (19.8% to 85%) most commonly affected.

Comparative Statistics: Musculoskeletal Conditions in Dentists vs. General Population

• Arthritis: 15.6% in dentists vs. 17.7% in the general population
• Cervicalgia (neck pain): 67% in dentists vs. 13.8% in the general population
• Lower back pain: 65% in dentists vs. 26.8% in the general population

Importance of Posture

• Dentists and dental students often assume awkward physical postures while providing treatment

Seated Position

• Facilitates muscle stillness.
• Supports high-precision work.
• Meets both visual and gestural needs.
• Preserves the balance of the vertebral column, muscles, ligaments, facets, and intervertebral discs.
• Negative: Poor seated positions generate TMS

Cardiovascular Issues

• Static positions are poorly tolerated in either a seated or standing position and pose a cardiovascular risk.
• Prolonged sitting leads to physical inactivity.
• Muscular contractions that occur with a lack of sedentary prolonged positions increases the risk of cardiovascular illness and diabetes.
• Risks include weakened blood flow, muscle atrophy, impaired brain oxygenation, cardiac insufficiency, and increased diabetes risk.

Mortality risks due to seated positions

• Each hour beyond four hours of sitting increases mortality by 2%
• Above 8 hours of sitting increases risk increases mortalitiy by 8%
• Above 10, morbidity increases to 34% according to Pr Michel Galinier

Trouble of vision

• The eyeis the dentists primary tool
• Activity requires visual acuity
• Fatigue caused by extended focus, accommodation efforts, and direct bright lights.
• Exposes the eye to 2000 hours annually of artifical light
• Iris opens and closes to a difference between light and dark, causing fatigue.

Hearing Issues

• Auditory issues are rising as chronic diseases.
• Professional exposure above 80 dB requires action.
• Three significant thresholds: risk (80 dB), danger (85 dB), and pain (120 dB).
• Dental tools (suction, turbines, compressors, etc.) average 78-85 dB, posing a risk.
• Outside noise such as alarms adds pential fatigue and aggression

Stress and Psychological issues

• Causes of stress includes difficult work and patients
• Work conditions includes noise, position causing physical fatigue, vision, and isolation
• Patient relations due to strong emotional states, tardiness, or complications
• Symptoms can be emotional (nervousness), intellectual (focusing), or physical (headaches)

Classification of Professional Gestures According to Kilpatrick

• Kilpatrick sought to streamline dental practice and boost productivity, adopting a 4 handed approach, and divided movementd into 5 categories
• Classifications are based on kinematics and risk of TMS

Zone of work

• Zone of work is a space permitting the dentist to accomplish work without bending or extending

Kilpatrick's Movement Classes

• Class I: Finger movements
• Class II: Finger and wrist motion
• Class III: Involves finger, wrist, and elbow motions to take hold of an item near the oral cavity to be treated.
• Class IV: Incorporates finger, wrist, elbow, and shoulder motions, tube is grasped
• Class V: Includes movements of the fingers, wrist, elbow, shoulder, torso, and basin

Movement types include

• Restricting to class I, II, III movements helps maintain the avant bras is a favorable position.
• Classes IV, V are unfavorable since require more energy

Position of Work

• Position indicates the way in which a body is posed
• Postures is the position maintained for a long period of time
• Good positions enables comfort, effiency, safety and mental health

Types of Position can include

• Sitting - provides stability.
• Orthostatic - provides fatigue.
• 20°+ flexion poses risk

Best Practises for Proper Postions

• Chair setting positions that provide reduced energy, comfort and stability
• Body should be in straight alignment with tabouret, camber lumbar
• Body and head tilts, and shoulder and neck position

Practical Measures for Ergonomics

• Ideal visual distances are 25-30 cm with no strain
• Proper patient head positioning and lighting with the operation lamp intensity is adjustable to patients denition

Assistance can be used in

• Assisting is used, maintain field of operation to remove saliva, and tranfer equipment
• Adjust the patients position so that the upper jaw is high

Decubitus Dorsal Postion

• It is a recommendation of European organization
• It is a normal sleep postion in which the cavity is oriented to a direct access to maxillary
• Demis possition enables an forward look

Doctor Hands Positions Relative to Patients Mouth

• The doctor hand and reference position can be the same when doing work on the A6H

Key Positions by area using clock

• Mandibular Rear/Right (48-44); Patient allongé, praticien à 8-9H, vision directe, faces occlusales et vestibulaires, vision indirecte, faces linguales.
• Mandibular Rear/Left (38-34); Patient allongé, tête tournée à droite, praticien à 11H, face occlusales et vestibulaires.
• Maxillary Left (24-28); Patient allongé, tête tournée à droite, praticien à 11H avec appui sur la têtière.
• Maxillary Right (14-18); Patient allongé, tête tournée à gauche, praticien assis 8-9H, faces vestsibulaires, faces linguales et occlusales.
• Maxillary Front (13-23); Patient allongé, praticien assis 12H, faces vestibulares and faces linguales.
• Mandibular front(33-43); Allongé, praticien à 12H, faces linguales vision directe, faces vestibulaires vision indirecte.

Conclusion

• Working pain/stress free in an environment supporting mental focus depends on the posture and awareness of the movements by dentist