著者

仲西 修 山室 宰 亀山 秀一郎 天野 裕治 東 真実 今井 弘貴 梅田 健一郎 椎葉 俊司 西 正勝

出版者

九州歯科学会

雑誌

九州歯科学会雑誌 (ISSN:03686833)

巻号頁・発行日

vol.48, no.4, pp.463-472, 1994-08-25 (Released:2017-12-21)

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This study was undertaken to assess the effect of different concentrations of nitrous oxide combined with a low dosage of midazolam on pain sensation in the buccal region of the human face. Twenty healthy subjects (male : 16, female : 4), male and female varying in age from 23 to 28 years (mean ; 24.9 years) and from 23 to 30 years (mean ; 25.8 years), and weighing from 52 to 85 kg (mean ; 66.1 kg) and from 46 to 49 kg (mean ; 47.1 kg) respectively, were involved in this study. All subjects were administered midazolam (0.025 mg/kg) intravenously, and divided into three groups ; the first inhaled 25% N_2O and 75% oxygen (25% N_2O group), the second inhaled 40% N_2O and 60% oxygen (40% N_2O group), and the third inhaled 60% N_2O and 40% oxygen (60% N_2O group). All subjects were reclined on dental chair comfortably in the supine position 10 minutes prior to start of the experiment. Three control tests were carried out with inhalation of room air at 10 minute intervals. One of the three concentrations of nitrous oxide (25% N_2O, 40% N_2O and 60% N_2O) was inhaled within 5 minutes by face mask after injection of midazolam into the forearm without the subject's knowledge for 30 minutes, and the mask was removed after oxygen inhalation for 5 minutes in succession after turning off the nitrous oxide gas. Three tests each for thresholds of tactile sensation using nylon^[○!R] thread (point load 0.004 g, 0.01 g, 0.2 g), and of pain sensation using an esthesiometer (point load 1-10 g) on the buccal region of the face were made at 10 minutes' intervals during N_2O inhalation and withdrawal periods. The results obtained are as follows. 1) The threshold of tactile sensation in the buccal region increased 17% and 19% over the control in the 40% N_2O group and the 60% N_2O group, respectively, but there were no significant differences between the groups. 2) The threshold of pain sensation in the buccal region showed significant increases from the control value in the 40% N_2O group during N_2O inhalation period, and the 25% N_2O group and 60% N_2O group showed significant increases from the control value at the 10 minutes point and 30 minutes point in the inhalation period, respctively. Especially in 40% N_2O group, significant increases were seen much more than in the 25% N_2O group at the 30 minutes point in the inhalation period. 3) In the condition of consciousness of 25% N_2O group and 40% N_2O group, there were significant differences during the N_2O inhalation term, and significant decreases appeared in blood pressure and heart rate during the N_2O inhalation term. These results indicate that the analgesic effect of 40% nitrous oxide combined with midazolam and the sedative effect of 25% nitrous oxide combined with midazolam are better than those of the other concentrations of nitrous oxide. It is the best way of the dental treatment to use infiltration under the 25% nitrous oxide with midazolam (0.025 mg/kg) for patient pain and fear.