Special Considerations for Equipment Arrangement Four-Handed Dentistry

Not all treatment rooms are the same. For instance, in a dental specialty such as Pediatrics or Orthodontics, the room design may differ from the individual private treatment rooms of a typical general practice. Thus, the space and equipment arrangement may be modified to resemble a clinic type environment. However, the basic concepts of four‑handed dentistry and the criteria for dental equipment in these facilities remain the same.

Figure 8.
fig08 clinic arrange
A clinic style arrangement for an orthodontic practice.
Figure 9.
fig09 individ room arrange
A separate room within a clinic style format for a pediatric practice.

True four‑handed dentistry is ergonomically the most favorable way to provide dental services since it minimizes undesirable movements of the operating team and expedites the progress of most dental procedures (Figure 10).1 To maximize effectiveness, a geographically favorable arrangement of the work environment must exist. The most favorable arrangement requires the selection of equipment be based on the assistant’s work area adjacent to the dental chair, since most of the movement of instruments and materials occurs in that area during a treatment procedure (Figure 11). Over the years some manufacturers have attempted to meet this criterion and failed. Some of the original research done at the University of Alabama School of Dentistry during the evolution of the concept of four‑handed dentistry during the 1960’s is still among the most reliable in meeting these criteria.2

Figure 10.
fig10 dentist
Figure 11.
fig11 assistant

True four‑handed dentistry simply cannot be performed successfully if the dental team must use excessive movement to reach for instrumentation, become entangled in an array of hoses and power cords, or are unable to comfortably access the operative field.

Many dentists attempt to purchase equipment at a dental convention. However, this is not the opportune time to make a major investment, since there are so many displays and one becomes confused by the myriad of sales pitches about which is the best equipment for you. The dental team needs more than a cursory review of the equipment. The team must work with the equipment and spend time with ergonomic specialists to understand the impact the new equipment will make in the office. Equipment selection may mean a visit to the manufacturing company or to a colleague’s office where the equipment of choice is actually used. If inappropriate equipment is purchased, it will likely result in undue stress when used over a period of time.

An often-overlooked factor when choosing a dental unit for ergonomic practice is that the dental assistant should be the primary focus. This will relieve the dentist of unnecessary movement during dental procedures. Accessibility to handpieces and other dynamic instrumentation should be primary to the assistant and secondary to the dentist (Figure 12).2 If the dentist must reach to retrieve a handpiece or air-water syringe, time is lost; excessive motion and physical strain can result.3 Likewise the position on the unit of the handpieces should be determined by frequency of use. For instance, the high-speed handpiece should be closer to the doctor than the slow speed handpiece, and the high velocity evacuator and air/water syringe should be closer to the assistant than the saliva ejector. To minimize movements, all instruments should be within a 21-inch radius of the assistant for efficient instrument transfers to the dentist to occur (Figure 13).1

Figure 12.
fig12 dental unit left
The dental unit is on the assistant’s left and the trays in front on the mobile cart.
Figure 13.
fig13 unit 21in reach
The dental unit must be within a 21 inch radius of the assistant’s hand to ensure easy access to the handpieces.