Evaluating Equipment Designs
The basic dental unit designs available today include the side delivery, rear delivery, split unit/cart, and transthorax. Figure 4 provides schematic examples of the four common unit styles.
Side Delivery (Figure 4A)
This unit has been a popular concept for many
decades. In fact, several dental schools use this style of unit often
supplied with a bracket tray since dental students often have to work without a
dental assistant. Some units of this style even include a cuspidor that
interferes with the assistant's position and creates an infection control
problem as well as a physical challenge for a patient if they were to actually
use it. This style unit requires the dental operator to retrieve and
replace the handpieces which, in turn, forces the shift of vision from the
treatment site, twists the upper body to turn to grasp the wanted instrument,
and then refocus the eyes back on the operative field. This can result in
physical stress and eye fatigue. The side delivery style configuration
prohibits the assistant from reaching the instruments to exchange handpieces or
change burs that requires more unnecessary movement by the operator, thus,
reducing productivity. Often in this arrangement, high velocity evacuation
(HVE) is placed on the assistant's side of the chair that, in turn, forces the
assistant to be positioned too far away from the patient. At times, HVE
hoses are located on the assistant's mobile cart. The concern here is
whether the addition of the hoses to this cart diminishes the cart's
effectiveness. The hoses may impede the function of a sliding top or
encroach on valuable storage space in the cart.
Rear Delivery (Figure 4B)
The operator is forced to retrieve and replace the
handpieces with this style of unit. This requires extensive twisting and
turning as well as eyestrain as the operator is forced to turn from the
operating field to pick up a handpiece. It is often necessary to transfer
the handpiece from the retrieval hand to the operating hand in order to use
it. The units are mounted in a fixed position that cannot be moved to
accommodate for the changing working positions of the operator or for ease of
use for the assistant. HVE hosing and air/water syringes are permanently
affixed to an assistant's work area. Since it is in the rear, it requires
the assistant to lean forward. When a mobile cart is used with the rear
delivery unit concept, it may interfere with access to the sink or to the HVE
and air/water syringe. For the assistant, this can provide undue stress
and strain and limit access for increased productivity.
Despite the ergonomic disadvantages, rear delivery units remain popular because they are attractive furnishings for the treatment room and hide the dental unit from the patient's view.
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| Citation Number: Vol. 2, No 4, Page 046 |
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