Dental professionals experience high rates of musculoskeletal disorders due to poor ergonomics. Proper patient positioning, operator positioning, and instrument exchange can help reduce strain. The patient's head should be supported and their body positioned for optimal access. The operator should sit upright and keep treatment sites at elbow level to minimize fatigue. The assistant aids efficiently by preparing instruments in sequence within the designated exchange zone.

1. Chair and operator positions

2. • An average of two out of three dental professionals experience occupational pain.
• Nearly a third of dentists who retire early are forced to do so because of a
musculoskeletal disorder.
• In 2004, approximately $131 million was lost in income due to MSDs in the dental
profession.

7. FEATURES OF A DENTAL CHAIR

8. PATIENT POSITIONING ON A DENTAL CHAIR
• Patient should be seated so that all his body parts are well supported.
• The patient's head should always be supported by adjustable/ articulated
headrest.
• Preferably the patient's head should be in line with his back
• The chair height should be kept low, backrest should be upright and armrest
should be adjustable while making the patient to seat in the dental chair.
• Now, the chair can be adjusted to place the patient in reclining position.
• Patient position can vary with operator, type of procedure and area of the oral
cavity.

9. For restorative dental procedures, the most preferred operating positions are:
1. Upright position
2. Almost supine
3. Reclined 45 degree
CHAIR POSITIONS DURING DENTAL PROCEDURES

13. OPERATING POSITIONS
Once the patient has been comfortably positioned, the dentist and
the assistant should sit themselves in the proper positions for
treatment.
Usually sitting position is preferred in modern dentistry to relieve
stress on operator's leg and support the operator's back.
The level of teeth being treated should be placed at same level as
the level of operator's elbow.

14. For better understanding, sitting
positions of operator are related to a
clock. In this clock concept, an
imaginary circle is drawn over the
dental chair, keeping the patient's
head at the center of the circle.
Then the numbering to circle is given
similar to a clock with the top of the
circle at 12 o'clock.
Accordingly the operator's positions
(right handed operator)
7 o'clock, 9 o'clock, 11 o'clock, and 12
o'clock
Left handed operator's positions ,
5 o'clock, 3 o'clock and 1 o'clock .

20. 1. While doing work in Maxillary arch, maxillary occlusal surfaces should be
perpendicular to the floor.
2. In Mandibular arch, mandibular occlusal surface should be oriented 45° to the floor.
3. Patient's head can be rotated backward or forward or from side to side for operators
ease and visibility while doing work.
CONSIDERATIONS FOR DENTISTS WHILE DOING PATIENT

21. 4.The dentist operator should always maintain distance from the patient such as
distance while reading a book. Maintain proper working distance during dental
procedure. This will lead to increase cooperation and confidence among the patient.
5. Another important point is to avoid minimize body Contact with patient.
Dentist should not rest forearms on the patient's shoulders and hands on the face of
the patient.

22. 6. Dentist should not use patient's body as a instrument trolley.
7. The operator should leave left hand free during most of dental procedures for
retraction using mouth mirrors or fingers of left hand.
8. Operator should keep changing position if procedure is of long duration to
decrease the muscle strain and fatigue.

23. There are various varieties of stools available in the
market
There are several features of operating
Stool which should:
1. Have casters for mobility and easy movement
2. Be durable and well balanced
3. Have seat which is well padded with cushion
4. Have adjustable backrest to provide full support to the
dentist.
Operating Stool

24. 1. The dentist should sit on the back of the cushion rather than edges
2. The dentist should sit on the stool such that:
• Spiral column is straight or slightly bent taking the advantage of backrest
• Thighs are parallel to the floor
• Lower legs are perpendicular to the floor.
3. The patient should be lowered to a position that places the treatment site as close
to the dentist's elbow level as possible.
SITTING ARRANGEMENT OF OPERATOR AND ASSISTANT

25. 4. Nowadays, stools having backrest with curved extensions that provide additional body
support are also available.
5. If seat is positioned too high, the edges will cut off supply to user's legs resulting in
more fatigue and stress.
6. Assistant should sit as close as possible to the back of the patient's chair with feet
directed towards the head of the chair
When the patient is properly positioned, the dentist's eyes should be 14 to 16 inches from
the treatment site

26. 7. Stool height of assistant should be 4 to 6 inches above
the dentist's eye level.
8. The assistant should sit in an erect position with feet
firmly placed on the foot-support ring at the base of
the assistant chair.
9. The instrument tray should be placed toward the
head of the patient's chair, and positioned to allow
easy access to the instruments and materials.
10. Above positions can be adjusted according to specific needs.

27. The working area is divided into four zones :
1. Operator's zone (lies between 7 to 12 0' clock)
2. Assistant's zone (lies between 2 to 4 o'clock)
3. Static zone (lies between 12 to 2 o'clock)
4. Transfer zone (lies between 4 to 7 o'clock)
Zones of Working Area

28. The efficient exchange of instruments between the operator and the dental assistant
is fundamental to have an efficient and stress free dental practice.
The transfer of instrument between the operator and assistant should occur in
exchange zone which is below the patient's chin and several inches above the
patient's chest.
Instrument Exchange Zone

29. To increase efficiency, and reduce stress and fatigue of the dentist and the assistant, there
should be cooperation from the both sides.
To accomplish this, the assistant should know the sequence of the treatment steps and have the
required instruments and materials ready at the proper time.
Ideally, the instrument transfer is accomplished with a minimum and smooth motion.
As a rule the instruments should be set from left to right, in the sequence in which they are to
be used.
Instrument Exchange