National Maternal and Child Oral Health Resource Center | Georgetown University
Unit 2: Facilities & Staffing
facilities and staffing

Section 2. Equipment and Supplies

Delivery Systems

The three most commonly used delivery systems for patient treatment (over-the-patient, rear, and side delivery) are compared below, with photos and some of the advantages and disadvantages of each.

Over-the-Patient Delivery

This system is most used in dental clinics today. The system design meets the requirements of time and motion concepts and promotes good ergonomic positioning. With the unit over the patient, the assistant can easily retrieve the handpieces and transfer them to the dentist, who does not need to look up from the treatment site. There are no hoses to interfere with the assistant’s position. This type of unit has been designed for the practice of true four-handed dentistry. Also, if the dentist is working alone, the handpieces are easily accessible.

Photo of an Over-the-patient Delivery System

Advantages Disadvantages
  • The most ergonomically sound system for the dentist
  • Easily converts to left-handed or right-handed (very important)
  • Moves up or down with the chair to maintain a constant relationship
  • Provides the most practical use of space
  • Allows dentist and assistant to handle instruments and switches
  • Allows the dentist to release the handpiece without looking up from the treatment site
  • Most visible system to patients in terms of seeing the instruments
  • Is very confining for patients
  • Patients may bump into unit if they rise up suddenly
  • Not generally recommended for treating children or patients with conditions that result in aggressive behavior or unpredictable movements
  • A patient's feet can get tangled in the handpiece cords

Rear Delivery

The dentist must pick up the handpiece, which requires extreme twisting and turning, since the dentist is forced to turn from the operating field to pick up the handpiece. Often it is necessary to transfer the handpiece from the retrieval hand to the operating hand. The units are mounted in a fixed position that cannot be moved to accommodate the positions of the dentist or for ease of use for the assistant. High-volume evacuation hosing and air/water syringes are permanently affixed to an assistant’s work area.

Photo 1 of a Rear Delivery System
Photo 2 of a Rear Delivery System
Advantages Disadvantages
  • Least expensive system and easily combinable with an assistant cart for little additional expense
  • Easily converts to left-handed or right-handed
  • Least visible system to patients in terms of seeing the instruments
  • Easy patient access to dental chair
  • Less confining to patients
  • Allows handpieces to be transferred and burs to be changed by the assistant
  • Easy to connect to in-wall utilities
  • Less ergonomically sound system for the dentist, who must twist to reach handpieces or instruments
  • Places the dentist at increased risk for sharps injuries from dental burs, due to the location of the handpiece holder near the dentist's forearm
  • Cords can become tangled and difficult to position for efficient use
  • Requires two entries to operatory—one for the dentist and one for the assistant
  • Makes working alone or standing up difficult for the dentist

Side Delivery

This system has been popular for many decades. In fact, most schools use this system, often supplied with a bracket tray. This system requires the dentist to pick up the handpiece, so the dentist must look up from the treatment site, twist to grasp the instrument, and then refocus. The assistant is not able to reach the instruments to exchange handpieces or change burs, reducing productivity that is gained from four-handed dentistry.

Photo of a Side Delivery System

Advantages Disadvantages
  • Easy patient access to dental chair
  • Less confining to patients
  • Easy to connect to in-wall utilities
  • Most do not convert to left-handed and right-handed
  • Handpieces are inaccessible to assistant, so dentist must change burs on handpieces
  • Ergonomically less sound for the dentist, who must twist to reach for handpieces or instruments
  • To release the handpiece, the dentist must look up from the treatment site