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Inside Dentistry
June 2015
Volume 11, Issue 6

The Evolution of Instrument Management and Dental Cassettes

Advances in safety and infection control reflect changing times

Marie T. Fluent, DDS

The delivery of oral health care today hardly resembles dentistry of yesteryear. Our dental forefathers of 100 years ago might perceive much of our current equipment, supplies, and materials as science fiction. Over the past century, infection control products, policies, and protocols have also advanced. In response to disease threats, safety issues, and ongoing research, infection control guidelines have been developed and regulations implemented. Manufacturers have responded to these changes with many products, including instrument-management systems designed to help clinicians adhere to regulations while facilitating safe, effective, and efficient instrument processing.

Instrument Management in the 19th Century

A dental history museum displays an instrument case dated 1840. This sturdy wooden box is velvet lined and contains multiple compartments, sliding drawers, and a handle, because dentists of this era traveled to various towns to treat their patients. Although minimal literature exists regarding instrument management in the 19th century, one might speculate that high-priority instrument-management factors included portability, durability, a professional presentation to patients, and organization of instruments. What is not evident in this instrument-management system, however, is any evidence of infection control or safety considerations for either the operator or the patient.

Dental Cabinets in the Early 20th Century

In the early 20th century, dentists typically remained stationary in private dental offices. Dental cabinets of this period contained a myriad of small drawers and compartments. Working instruments were placed on a small bracket table and instruments were stored (unwrapped) neatly within drawers. Although Robert Koch postulated the existence of a causative relationship between microbes and disease in 1884, it seems dentistry remained unaware that cross infection could occur between patients and dental personnel into the 20th century. However, some awareness of this concept occurred in the early 1900s, as a medical journal from 1916 notes, “the possibility of the transmission of disease through the medium of dental instruments has probably been considered by every occupant of the dentist’s chair.”1 That article proceeds to mention “the conveyance of contagion in this manner is extremely rare, its frequency not being determinable, although few will deny the possibilities.”1 Dental manufacturers responded to this new knowledge by producing dental cabinets with a “sterilizer” in the upper chambers. Although instrument processing, sterilization, and storage of the early 1900s were not consistent with today’s regulations and standards, it is evident that some efforts were made to clean and disinfect instruments between patient usages.

Introduction of Four-Handed Dentistry: the 1970s

Four-handed dentistry was introduced and became commonplace in the mid-1970s. Dentists began to employ dental assistants to improve efficiency, shorten treatment times, and reduce fatigue. Instrument-management systems in this era evolved to reflect these changes. Preset instrument trays stocked only with items needed for a given procedure reduced the amount of time needed to set up.3 Among the approaches to instrument processing in the 1970s were some—marked with an asterisk here—that do not comply with current standards and regulations:

· Instruments were scrubbed with bare hands and a short-handled brush,* and then sterilized in either a cold sterilization solution or a heat autoclave or chemclave.
· Instruments that were not sterilized were often wiped clean with a 2-inch x 2-inch square of gauze and rubbing alcohol.*
· Instruments were sterilized in open baskets and stored unwrapped on open trays or in glass instrument trays in drawers.*

Thus, instrument management of the 1970s emphasized organization and efficiency during patient care; however, instruments were easily lost or misplaced during cleaning, sterilization, and storage. Infection control and safety were not emphasized features of instrument management, as dental personnel of the 1970s had no way of knowing then the impending emerging infectious disease threat that would forever impact their profession.

Infection Control in the 1980s

In the early 1980s, the AIDS epidemic hit. The discovery and spread of this deadly disease precipitated widespread panic and fear of being exposed to infectious diseases.3 Hence, infection control guidelines were developed, regulations were mandated, and an infection control protocol was refined. In 1986, the Centers for Disease Control and Prevention published their first comprehensive dental infection control guidelines and adopted “universal precautions” based on the concept that all blood—and body fluids that might contain blood—might be contaminated and should be treated as infectious. As a result of these events, the management of dental instruments shifted. Where organization and convenience were once emphasized, newer considerations—including infection control and safety for dental personnel—became paramount.

As regulatory guidelines emerged, clinical applications of infection control protocols evolved, and manufacturers slowly respond to the needs of clinical personnel. In this era, instruments were commonly sterilized unwrapped in an open basket or in a separate container, and subsequently transferred to a tray.3 Instruments were frequently handled during transfer, increasing the likelihood of injury, and instruments were routinely stored uncovered, compromising sterility. Further, dental personnel often improvised to manufacture their own instrument-management supplies. In fact, a dental assisting textbook from this period suggested that custom-made instrument mats could be fabricated from grooved-style automobile floor mats that are available at many auto supply stores. The text held that these mats were durable, low in cost, and could be autoclaved.3

The Introduction of Dental Cassettes

Instrument cassettes were manufactured and introduced to the dental profession in 1984 as a way to comply with infection control protocol and enhance a safe and efficient means of instrument organization and management. Cassettes provide a built-in tray for delivery during patient care. Instruments are protected, as they are safely enclosed within the metal casing; dental personnel are protected because sharp tips of instruments cannot poke through. Further, procedures are streamlined as all instruments needed for a given procedure are included within the cassette, and setup and breakdown are simplified because the process of searching for missing instruments is eliminated. In this system, instruments can be safely carried from the operatory to the instrument processing area.

Advancements in Dental Cassettes

While the basic premise of a cassette as an instrument management system remains, there have been recent technological advancements. First, the existence of many more options in sizes and configurations allows for personal preferences of instrument set-ups for individual providers or procedures. Color-coded rail systems hold instruments securely in place while reducing the amount of instrument contact, allowing for more efficient cleaning of instruments. Cassettes now have larger hole configurations, which are compatible with both ultrasonic cleaners and automated instrument washers and allow more efficient cleaning, rinsing, and drying.


The evolution of instrument management has paralleled modern dentistry. The characteristics of an ideal instrument management system include organizing and protecting dental instruments and promoting the safety of clinical personnel. They would also maximize efficiency during setup, breakdown, and delivery of patient care as well as improve ease of cleaning, sterilizing, and storing instruments. The development of dental cassettes has improved each phase of instrument processing and patient care. The evolution of dental cassettes is an example of manufacturers’ responding to infection control regulations as well as the needs and safety of dental personnel.

For a table comparing instrument management then and now, visit


1. Andrews RH. The Medical Summary. 1916; 37(11):342.

2. Guidelines for Infection Control in Dental Health-Care Settings, 2003. Centers for Diease Control and Prevention website. Accessed May 5, 2015.

3. Chasteen J. Essentials of Clinical Dental Assisting. 4th ed. St. Louis, MO: Mosby; 1989: 80-102.

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