The history of inhalation sedation and its use are well documented. Inhalation sedation with nitrous oxide (N₂O) and oxygen (O₂) has withstood the test of time as the safest of all sedation techniques used in the history of medicine and dentistry. The story of N₂O began with its discovery by Sir Joseph Priestley and the experimentation and subsequent documentation of some of the effects by Sir Humphrey Davy. The involvement of Gardner Colton and even Samuel Colt, inventor of the popular revolver, as entrepreneur showmen added color, entertainment, and most importantly clinical experience to the use of N₂O. Horace Wells, a dentist and acknowledged discoverer of anesthesia, ushered into the medical field the tremendous possibility for pain control. However, this initial discovery did not burst onto the scene; in fact, it was almost overlooked, but ended up changing human history forever.

Reading the history of N₂O can give one a special appreciation for Gardner Quincy Colton. His unselfishness in teaching Horace Wells how to manufacture N₂O led to its discovery. His documentation of more than 170,000 cases of N₂O administration without mortality gave testimony to his clinical skill and dedication to the advancement of pain control.

As has been mentioned throughout this section, inhalation sedation with N₂O and O₂ is the safest of all sedation techniques currently available. Factors responsible for this include the nature of the gases used, the manner in which they are administered (with not less than 30% O₂), the addition of fail-safe devices to inhalation sedation units, and the upgrading of education in the use of inhalation sedation. This last factor is discussed in this chapter, for although great strides have been taken in improving the educational process in teaching inhalation sedation, there remain many persons who seek an easy way out, looking for shortcuts to make the technique even simpler to learn. To maintain the safety of inhalation sedation, high standards for education must be ensured and gradually increased as our knowledge of the technique continues to grow.

As mentioned in Chapter 11, one reason for the failure of inhalation sedation to maintain its popularity among the dental profession in the 1930s and 1940s was the absence of educational programs. Dental schools did not include the use of N₂O-O₂ in their curricula, and continuing education programs were essentially nonexistent at that time. Drs. Harry Langa and Harry M. Seldin were instrumental in providing education with some uniformity and baseline criteria for didactic and clinical training of dental students.

In an effort to provide a uniform level of education in the teaching of different techniques of anesthesia and sedation within the dental school curriculum, three groups—the American Dental Society of Anesthesiology (ADSA), the American Dental Association (ADA), and the American Association of Dental Schools (AADS; now American Dental Education Association [ADEA])—sponsored four workshops on pain control in 1964, 1965, 1971, and 1977. From these conferences emerged the Guidelines for Teaching the Comprehensive Control of Pain and Anxiety in Dentistry.^1,2 The guidelines provide outlines for a curriculum in pain control at three levels: (1) the undergraduate dental student (doctoral student), (2) graduate dental student (postdoctoral student), and (3) in a continuing education program. These guidelines were approved by the ADA’s Council on Dental Education in May 1971.² In 1977 part III of the guidelines, relating to continuing education programs, was revised. The revised guidelines were approved by the House of Delegates of the ADA in 1978.³ Part I of the guidelines underwent revision in 1979,⁴ with the entire document revised again in 1992.⁵ Sections of the most recent revision of the guidelines (as adopted by the ADA House of Delegates in 2007) relating to moderate sedation and then more specifically inhalation sedation in continuing education programs are discussed here.⁶