is recommended to decrease biomechanical loads
to trapezoid muscle [12,13]. More than 20 degrees
of forward and sideward flexion of the neck is an
interpretation of the REBA mean of 2.92 for this
organ, which is the unfavorable position of the
neck that results in 50.8% of the disorders. Unsuitable
lighting conditions can be added to the aforementioned
list. It appears that, use of dental mirrors
for indirect vision can significantly prevent
such disorders. A 105 degree angle between the
trunk and the leg dictated by the working stool as
well as a 10- to 20- degree forward cant of the seat
is essential for a better vision and a less cervical
and lumbar flexion [14,15].