I. Introduction

Pain and the fear of pain have long been associated with dentistry. Modern dentistry has the means to control pain, either with safe reliable local anesthetics, intravenous sedation, or for some cases, general anesthesia. Yet, for many people, the fear of dentistry remains a serious deterrent to seeking and receiving needed dental treatment. In the US annually, 155 million people have acute pain at least once a year, yet 35 million people in the US avoid dental care because of fear. ¹

To a large degree, success in dentistry requires the recognition and effective treatment of fear and anxiety in patients. Local anesthesia does not necessarily reduce fear, and in fact, since it is administered by a "needle" may be the source of fear itself. A broad range of anxiety control methods are available to dentistry today. With the exception of hypnosis and acupuncture, all methods employ the use of drugs that produce effects from mild forms of sedation to general anesthesia. This course is concerned with only one of these drugs, nitrous oxide.

Other sedative or tranquilizing drugs can be, and occasionally are, combined with N₂O sedation to enhance the effect. However, it should be noted that the combination, while giving greater effect, also may produce increased risk of complications. This course has not been constructed to include information for the provision of oral or intravenous sedation, therefore, this course will be concerned primarily with the use of nitrous oxide-oxygen.

You will find some of the information will be repeated in different chapters. These points are obviously felt to be important issues that we want you to be well aware of, often in different contexts. Hopefully, you will not find the redundancy disconcerting.