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IMPORTANT CHAPTER IN ORTHODONTICS : ERGONOMICS

ABSTRACT
Orthodontists are commonly exposed to a variety of occupational hazards such as musculoskeletal disorders which can limit the quality of work provided by the dental professional towards their patients and ultimately affect the long term health of the orthodontist. The traditional methodology for prevention and management of dental related musculoskeletal pain was to adopt a proper sitting posture, reduce large scale movements and perform periodic stretching. Proper ergonomic design is crucial to prevent repetitive strain injuries, which can develop over time and can lead to long-term disability. Ergonomics is concerned with the ‘compatibility’ between people and their work. It takes account of the worker’s capabilities and limitations in seeking to confirm that tasks, equipments and the environment suits each worker. This article provides alternatives that should be considered by the practioner to improve his or her work environment and daily practice to reduce the risk of musculoskeletal disorders and improve the quality of care towards the patient.

INTRODUCTION
In Greek, “Ergo” means work and “Nomos”, means natural laws or systems. The international ergonomics association has defined ergonomics (or human factors) as the scientific discipline concerned with the understanding of interactions among humans and other elements of a system and the profession that applies theory, principles, data and methods to design in order to optimize human well-being and overall system performance.

Musculoskeletal pain can affect the dentist’s performance in several ways, which include limiting the number of patients seen per day, decreasing fine motor dexterity and hampering dentists-patient rapport.2 Because of the narrow work area, performance of dental treatment results in a very inflexible work posture and ultimately affect the quality of care. Not only this, stress on muscles and joints can lead to more serious conditions over time. Surveys of Dental Professionals reveal that more that 60 percent of dentists and hygienists experience often debilitating muscle and joint pain as a result of their work.

One of the main goals of ergonomics in dentistry is to lessen the amount of physical and mental stress that sometimes happens day to day in a dental practice. Applying ergonomics to the practice of dentistry will not only provide safety benefits but also improve performance objectives through greater productivity.

SIGNS AND SYMPTOMS OF MUSCULOSKETAL DISORDERS
Improper ergonomic design can lead to repetitive strain injuries, which can develop over time and can lead to long-term disability. Some of the signs and symptoms of musculoskeletal disorders include:-
a)    Upper & lower backache
b)     Rotator cuff tendinitis
c)    Brachial nerve compression, tension neck syndrome, cervical spondylitis
d)    Ulnar nerve entrapment
e)     Carpel tunnel syndrome
f)    Tenosynovitis
g)     Tendinitis

ETIOLOGY
The primary occupational risk factors for musculoskeletal disorders include:-
1.    Awkward posture
2.    Improper adjustment of equipment
3.    Infrequent breaks
4.    Repetitive movements

STRATEGIES FOR REDUCING ERGONOMIC PROBLEMS IN DENTISTRY
VARIOUS INTERVENTIONS FOR CONSIDERATION IN THE DENTAL PRACTICE

1.    EQUIPMENT AND INSTRUMENT DESIGN:- Dentists should consider the ergonomic ramifications of the purchase and be aware about the ‘ergonomic designed’ ones. Considerations to be kept in mind are-
·    Overall shape/size
·    Handle shape/size
·    Weight
·    Balance
·    Manoeuvrability
·    Ease of operation
·    Ease of maintenance

In case of hand instruments, look for-
·    Hollow or resin handles
·    Round, knurled or compressible handles
·    Carbon steel construction (for sharp instruments)

While buying automatic hand pieces for your operatory, look for-
·    Lightweight, balanced models
·    Power should be sufficient
·    Built-in light sources
·    Angled versus straight shank
·    Pliable, lightweight hoses
·    Swivel mechanisms
·    Easily activated
·    Easy to maintain

In case of syringes and dispensers, look for-
·    Enough lumen size
·    Easy to clean
·    Knurled handles
·    Easy activation and placement

2.    EARLY TREATMENT OF MUSCULOSKELETAL DISORDERS:- Early interventions are important in order to achieve a better result at less cost and inconvenience. Early symptoms in the wrist and hand respond to conservative medical management that includes rest, icing, non-steroidal anti-inflammatory drugs and splints.

3.    PROPER POSTURE, STOOLS AND PATIENT POSITIONING:-
a) General posture in dental practice-
·    Patient chair:- a) up right, b) semi reclined, c) fully reclined.
·    Relationship of the dentist knee to the patient chair: – a) 90 degree, b) >90 degree, c) <90 degree.
·    Dentist posture:- a) while standing- flexion posture either A-O degree or B-35 degree (unfavourable), b) while sitting- flexion posture either       A-degree or B-20 degree or 30 degree.
·    Relationship of dentist to the patient’s chair:- a) at sternal level, b) below sternal level, c) above sternal level.
a)    Operator positioning :-
b)    Patient postioning :-
c)    Ergonomic guidelines for operator chair-
·    Stability
·    Lumbar support
·    Hydraulic controls
·    Cylinder height
·    Hands-free seat height adjustment
·    Adjustable foot rests
·    Adjustable, wrap around body support
·    Seamless upholstery
·    Adjustable backrest
·    Tilting seat pan
·    Textured seat material
·    Correct wheel type
·    Armrests
d)     Ergonomic guidelines for patient chair-
·    Stability
·    Pivoting or drop-down arm rests
·    Wrist/forearm support for operator
·    Hands free-operation
·    Narrow upper back that allows closer positioning
·    Swivel function that will allow the chair to rotate in the operatory
·    Sling or low profile armrests that helps the dentist to work in 8 o’clock-10 o’ clock position without hit their knees on a fixed metal arm rest
·    Large knobs should be absentas they hit the edge of operator chair, preventing close positioning
·    Adjustable chair height.3

4.    LIGHTING:-
•    For proper lighting and to prevent shadowing, it is advised that the operatory light should be parallel to, or within 15 degrees of the operator’s line of sight.
•    The intensity ratio between dental operating light should not be greater than 1.6-3
•    Fibre-optics adds concentrated light to the operating field.

5.    MAGNIFICATION:- Different visualisation aids used in dentistry are-
·    Procedure scope-it facilitates neutral head position and reduced eye fatigue. It makes use of an extra-oral camera that is placed above the patient’s mouth, which projects a magnified image of the oral cavity onto a large flat video screen mounted at eye level, allowing the operator to move freely around the patient while visualising the screen.
·    Microscope- it provides near neutral head position with proper adjustment. Indirect viewing of the oral cavity is achieved by the optics in the scope that bends the path of image to almost 90 degrees, allowing an upright posture.
·    Loupes- enable working posture of less than 25 degrees of forward head posture. Strength lies between 2x to 5x. These are available in 2 styles that is flip ups (front lens mount) and through-the-lens (fixed mounts).4

6.    FOUR-HANDED DENTISTRY:-
·    Eliminates unnecessary motion
·    Decreases twisting and turning movements
·    Decreases long reaches and unbalanced postures

7.    RELIEF EXERCISES:-
a)    Body stretching exercise
b)    Neck exercises
c)    Hand exercises
·    Hand clenching exercise
·    Wrist bending exercise
·    Finger strengthening exercise

CONCLUSION
Dental professionals are prone to unique muscle imbalances and require special exercises and ergonomic interventions to maintain optimal health during the course of their career. It is important to not only know the effective interventions, but also in what sequence to implement them. By making changes in the way we practice via incorporation of some of the suggestions discussed in the article into our regular routine during the work day will prove beneficial for the practitioner, as one will experience less fatigue and pain and will be able to provide quality service to the patients.

REFERENCES
1.    Sarkar PA, Shigli AL. Ergonomics in general dental practice. People’s JSci Res, 2012; 5(1):56-60.
2.    Chasteen JE. Four handed dentistry in clinical practice. St. Louis, CV. Mosby 1978.
3.    Gupta S. Ergonomic applications to dental practice. Indian Journal of dental research. 1Nov, 2011;22(6):816.
4.    Valachi B, Valachi K. Preventing musculoskeletal disorders in clinical dentistry: strategies to address the mechanisms leading to musculoskeletal disorders. The journal of the American Dental Association. 31Dec,2003 ;134(12):1604-12.