title: A placebo-controlled, double-blind, crossover trial on analgesic effect of nitrous oxide-oxygen inhalation.
abstract: BACKGROUND
  The sedative effect of nitrous oxide-oxygen (N2 O/O2 ) inhalation is relatively well established. Less in known about its analgesic effect.
  
  
  OBJECTIVE
  To determine the analgesic effect of N2 O/O2 inhalation on pulp sensitivity and jaw muscle pressure pain threshold in children.
  
  
  METHODS
  A placebo-controlled, double-blind, crossover trial with random allocation to two sequences: atmospheric air at the first session and N2 O/O2 at the second; or N2 O/O2 at the first session and atmospheric air at the second. Measurements included reaction time, pulp pain sensitivity, jaw muscle pressure pain thresholds and a VAS score of overall discomfort from the pain tests.
  
  
  RESULTS
  Fifty-six children (12-15 years) completed the study. N2 O/O2 inhalation increased reaction time (P < 0.001). Pulp pain sensitivity was reduced during N2 O/O2 inhalation (P < 0.001), but no effect was found after adjustment for the increased reaction time. Pressure pain threshold on the jaw muscle was also reduced during N2 O/O2 inhalation (P < 0.001), also after adjustment for reaction time (P < 0.005). An effect was still found 10 min after the mask had been removed (P = 0.03). No effect on VAS scores of discomfort from the tests could be found.
  
  
  CONCLUSIONS
  No analgesic effect of N2 O/O2 inhalation on pulp pain sensitivity was found, whereas an increased pressure pain threshold of jaw muscles was found.
authors: Department of Dentistry, Pediatric Dentistry, Health, Aarhus University, Aarhus, Denmark; Municipal Dental Service, Aarhus, Denmark.
authors: Anni Birgitte
authors: AB
authors: Grønbæk
authors: Peter
authors: P
authors: Svensson
authors: Michael
authors: M
authors: Væth
authors: Ingelise
authors: I
authors: Hansen
authors: Sven
authors: S
authors: Poulsen
mesh_terms: D000293:Adolescent; D000766:Anesthesia, Dental / Q000379:methods*; D018685:Anesthetics, Inhalation / Q000008:administration & dosage*; D002648:Child; D018592:Cross-Over Studies; D003718:Denmark; D003782:Dental Pulp; D003807:Dentin Sensitivity / Q000453:epidemiology / Q000517:prevention & control*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008406:Masseter Muscle; D009609:Nitrous Oxide / Q000008:administration & dosage*; D010100:Oxygen / Q000008:administration & dosage*; D010147:Pain Measurement; D017288:Pain Threshold; D010919:Placebos; D011312:Pressure
chemical_list: D018685:Anesthetics, Inhalation; D010919:Placebos; D009609:Nitrous Oxide; D010100:Oxygen