Preoperative dental anxiety and mood changes during nitrous oxide inhalation.

BACKGROUND: An estimated 35 million Americans experience significant apprehension about dental procedures, while an additional 10 to 12 million are considered to be "dental phobic" and avoid needed dental care altogether. Nitrous oxide is a general anesthetic used at subanesthetic concentrations to reduce anxiety during dental procedures. The purpose of this study was to characterize mood changes during nitrous oxide inhalation in patients with different levels of preoperative dental anxiety. METHODS: Forty-six patients who were to receive nitrous oxide during a dental procedure completed two anxiety scales. These patients were categorized into three groups: low anxiety, or LA, moderate anxiety, or MA, and high anxiety, or HA. They completed a visual analog scale of subjective effects before, during and after the dental procedure. RESULTS: A number of visual analog ratings, the majority of which could be considered pleasant, increased during nitrous oxide administration. It is significant that this increase in pleasant mood occurred in the HA and MA groups to the same degree as it did in the LA group. Patients in the HA and MA groups had elevated preoperative visual analog ratings of "anxious" that were reduced during nitrous oxide administration to a level equivalent to that reported by patients who had low preoperative anxiety. Patients in the HA group also had elevated preoperative visual analog ratings of "having unpleasant thoughts" and "feel bad" compared with the LA group. These ratings were reduced in the HA group to a level equivalent to that reported by patients in the LA group. CONCLUSIONS AND CLINICAL IMPLICATIONS: Regardless of their preoperative anxiety level, patients experienced a number of mood-altering effects during nitrous oxide inhalation, the majority of which could be considered pleasant. Ratings of an unpleasant nature decreased markedly in patients with high anxiety. These findings suggest that nitrous oxide may be an effective therapy in reducing patient anxiety during dental procedures.