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Dental Ergonomics.ppt

  1. 1. Ergonomics In Dentistry Dr. Prabhu Department of Public Health Dentistry
  2. 2. Objectives: By the end of this lecture you will be able to: •Become familiar with the field of Ergonomics. •Identify risk factors and stressful individual behaviors in dentistry which lead to injuries. •Learn how to apply preventive strategies, including good posture and positioning.
  3. 3. Outline: • Definition of ergonomics. • Ergonomics design goals. • Risk factors for MSDs. • Application of ergonomics in dentistry. • Four Handed Dentistry. • Work Simplification Techniques.
  4. 4. Definition • Derived from the Greek…”ergo” meaning work and “Nomos” the study of... Literally the study of work. • The International Ergonomics Association (IEA) defines ergonomics (or human factors) as • “the scientific discipline concerned with the understanding of the interactions among humans and other elements of a system, and the profession that applies theoretical principles, data and methods to design, in order to optimize human well-being and overall system performance.
  5. 5. Ergonomic Design Goals 1. Improve job process by eliminating unnecessary tasks, steps & effort. 2. Reduce potential for overexertion injury. 3. Minimize mental/physical fatigue potential. 4. Leverage workers ’skills/knowledge of their jobs to increase their satisfaction, comfort and fulfillment.
  6. 6. Consequences of Poor Design: • Discomfort →Chronic Pain • Accidents →Injuries • Fatigue →Increased Errors • Work-Related Musculoskeletal Disorders (WMSDs): -Low back pain**most common** -Tendonitis -Epicondylitis -Carpal tunnel syndrome( CTS)
  7. 7. • More than 70 percent of dental students of both sexes reported neck, shoulder and lower back pain by their third year of dental school. • Present in up to 81% of dental operators. • The common reason for early retirement among dentists is MSDs (29.5%) (JADA, Vol. 136, January 2005)
  8. 8. Risk factors contribute to MSDs: Prolonged use of vibrating hand tools. Static neck, back, and shoulder postures. Repetitive motions (e.g., scaling, polishing). Grasping small instruments for prolonged periods. Excessive Force (e.g. tooth extraction).
  9. 9. Application of Ergonomics in Dentistry
  10. 10. Application of Ergonomics in Dentistry Instruments Hand instruments Vibrating handpieces Equipments Lighting magnification Operator and patient chair Work postures Patient position Dentist position
  11. 11. 1-Instruments: • Hand instruments: Goal: to reduce force exertion while allowing for neutral joint positioning. Handle shape and size: -Dental instrument diameter ranges from 5.6 to 11.5 mm. -larger handle diameters reduce hand muscle load and pinch force. -Sleeves that fit over the handles of mirrors. -A round handle VS hexagon handle.
  12. 12. 1-Instruments: • Hand instruments: Weight: -Light weight instruments (15 g or less). - Hollow VS Resin Balance: -The instrument should be equally balanced within the hand so that the tendency to deviate the wrist is reduced. Sharpness: -As a tool becomes dull, additional force is required to perform tasks. Texture: -Knurled handles such as diamond-shaped or crisscross patterns Color coded instruments are easier to be identified
  13. 13. 1-Instruments: • Dental Hand Pieces: When selecting hand pieces, look for: • Lightweight, balanced models (cordless preferred). • Sufficient power. • Built-in light sources. • Angled vs. straight-shank. • Easy activation.
  14. 14. 2-Equipments: • Equipment layout: Dental equipment should be located in a manner which allows you to maintain a neutral working posture and reduce postural deviation while working.
  15. 15. 2-Equipments: Frequently used items: -“comfortable distance” (22–26 inches) -within a normal horizontal reach which is the arc created while sweeping the forearm when the upper arm is held at the side. Less frequently used items: - Should be placed within the maximal horizontal reach which created when the arm is fully extended.
  16. 16. 2-Equipments: • Lighting: Goal: to produce even, shadow-free, color-corrected illumination concentrated on the operating field to also awkward working postures. • Overhead light should be positioned as close as possible to the sight line. • Hand mirrors to reflect the light intra orally. • Use fiber optics in handpiece.
  17. 17. 2-Equipments: • Magnification: Goal: to improve the neck posture and provide clear vision. • Use of various magnification systems, dental professionals are able to increase their working distance and assume more of an upright body posture. • “surgical loupes” and can be mounted to a headband or onto the operator’s glasses.
  18. 18. 2-Equipments: • Patient’s chair: Goal: to promote patient comfort and maximum patient access. Look for: -Stability. -Pivoting or drop-down arm rests (for patient ingress/egress). -Supplemental wrist/forearm support (for operator). -Articulating head rests. -Hands-free or preset operation.
  19. 19. 2-Equipments: • Operator chair: Goal: is to promote mobility and patient access and to accommodate different body sizes. Look for: -Stability (5 legged base w/casters). -Adjustable lumbar support. -Seat height adjustment. -Adjustable foot rests. -Adjustable, wrap-around body support or arm supports.
  20. 20. 2-Equipments: • Operator chair: RGP’s new Straddle stool -provides optimal seating allowing for proper positioning of the spine and the pelvis. -the Straddle stool pre-positions you into an anterior pelvic tilt. -The angle of seat allows for proper balance of core muscles and allows for the maintenance of normal curvature without the use of a backrest and without placing stress on the lower spine.
  21. 21. Normal stool RGP Straddle Stool
  22. 22. 3-Position and postures: • Patient position: “Supine position” -The patient’s heels should be slightly higher than the tip of the nose. This position maintains good blood flow to the head. -An apprehensive patient is more likely to faint if positioned with the head higher than the heels. -The chair back should be nearly parallel to the floor for maxillary treatment areas. (Chin up) -The chair back may be raised slightly for mandibular treatment areas. (Chin down)
  23. 23. 3-Position and postures: Chair position when treating maxillary Arch Chair position when treating mandibular arch
  24. 24. 3-Position and postures: • Operator position: Neutral position is the ideal positioning of the body while performing work activities and is associated with decreased risk of musculoskeletal injury.
  25. 25. 3-Position and postures: • Neutral seated position in relation to the patient: 1.Forearms parallel to the floor. 2.Weight evenly balanced. 3.Thighs parallel to the floor and knees are apart. 4.Hip angle of 90°. 5.Seat height positioned low enough. 6.Shoulders relaxed & parallel with floor. 7.Eyes directed downward. 8.(14-16) inches distance should be between the patient’s mouth & clinician’s eyes. 9.Elbows close to sides. 10.Patient’s mouth at elbow height.
  26. 26. 3-Position and postures:
  27. 27. Some wrong Postures In Dental Office
  28. 28. How to avoid all this pain!!!! SCHEDULING
  29. 29. Scheduling Recommendations when scheduling include: •Incorporate brief “stretch break” periods between patients. •Develop a patient difficulty rating scale to ensure difficult treatment sessions are not performed consecutively. •Increase treatment time for more difficult patients. •Alternate procedures performed.
  31. 31. Four Handed Dentistry
  32. 32. Four handed dentistry: • Definition: “It is an ergonomically sound way to practice dentistry using the skills of the dental assistant while including work simplification techniques.” - The term “Four handed dentistry” was first recorded in a conference on “training dental students to use chair side assistants” in 1960.Since then, this term has been widely used. -Goal: to allow the dentist and assistant to function as a team in a seated position with maximal efficiency and minimal strain.
  33. 33. Four handed dentistry: • Basic tenets of four-handed dentistry: To practice true four handed dentistry, the following criteria must be met: 1.Minimize unnecessary motion, equipments must be ergonomically designed. 2.Both the operating team and the patient should be comfortably seated. 3.Pre-set trays are utilized. 4.The dentist assigns all legally delegable duties to qualified auxiliaries based on the state’s guidelines. 5.Treatment Plan of the patient is designed in advance in a logical sequence.
  34. 34. Four handed dentistry: • Zones of activity: - The work area around the patient is divided into four “zones of activity”. - Zones of activity are identified using the patient’s face as the face of a clock. • The four zones are: a)Operator’s zone. b)Assistant’s zone. c)Transfer zone. d)Static zone.
  35. 35. Four handed dentistry: N.B: The static zone, which is the zone of least activity. Instruments that are infrequently used such as the blood pressure equipment and portable curing light can be stored in this area.
  36. 36. Four handed dentistry:
  37. 37. Four handed dentistry: • Equipment setup design: The basic dental unit designs available today include: - Side delivery. - Rear delivery. - Split unit. - Transthorax.
  38. 38. Four handed dentistry: • Equipment setup design: Transthorax: - Promotes good ergonomic positioning. - Save Time and less motion. - The unit over the patient’s thoracic area. - The assistant can easily retrieve the handpieces and transfer them to the doctor who does not need to remove his or her eyes from the operating site.
  39. 39. Four handed dentistry: • Equipment setup design: Side delivery: - This unit requires the dentist to pick up the handpieces, which forces him to remove his eyes from the treatment site, twist and turn to grasp the instrument, and then refocus, this results in stress and fatigue. - The assistant can’t reach the instruments to exchange handpieces or change burs, reducing productivity. (HVE)
  40. 40. Four handed dentistry: • Equipment setup design: Rear delivery: - The units are mounted in a fixed position that cannot be moved and HVE hosing and air/water syringes are permanently fixed to an assistant’s work area. - The doctor must pick up the handpiece then transfer it from the retrieval hand to the operating hand.
  41. 41. Four handed dentistry: • Equipment setup design: Split unit/cart: - This concept places part of the dental unit on the operator’s side and the (HVE) and air/water syringe on the assistant’s mobile cabinet. - Doctor and assistant?
  42. 42. Four handed dentistry: • Types of Instrument Transfer: Single Handed Transfer Double Handed Transfer
  43. 43. Work simplification techniques: • Four principles of work simplification: 1.Elimination: A 100% saving can be accomplished by elimination of unnecessary equipment, instruments, steps in procedures and movements. 2.Combination: If the functions performed by two instruments or pieces of equipment can be combined into one instrument or a piece of equipment, or if two steps in a procedure can be combined to accomplished in one step, a 50% saving can be realized.
  44. 44. Work simplification techniques: • Four principles of work simplification: 3.Rearrangement: It may be possible to rearrange equipment and materials in the operatory, scheduling of patients, or steps in clinical procedures to take better advantage of available space and time. 4.Simplification: Every effort should be made to simplify dental office equipment and patient treatment procedures in order to introduce a minimum number of variables and permit the team to function most effectively.
  45. 45. Conclusion: • Considering the impact of ergonomically designed and chosen equipment on the efficiency, One must modify the workplace to reduce the possibility of injuries. • Among the various occupational hazards, MSDs are very much at the disposal of the clinician himself. • Adopting newer techniques, armamentarium and work strategies can definitely prevent detrimental changes in the future.