Considerable efforts were made to ensure that neither the patients nor the dentist performing the tests were aware of which group and sequence the child Selleck Silmitasertib was allocated to. Blinding of the chair-side assistant was not possible, as

she was administering the drugs. The patients could probably have been aware of the sedative effect of inhalation of N2O/O2. As this is part of the pharmacological effect of the dug, it could not be disguised, but patients were carefully instructed, not to communicate with the dentist performing the tests. Furthermore, the dentist only entered the operatory, performed the tests and left the operatory again without having any communication with the patients. Thus, bias due to these factors seems to have been reduced as much as practically possible. A suggestion for further studies could be to have asked the participants to guess whether they had received placebo or N2O/O2 selleck as a check of the blinding. The present study was conducted as a crossover trial with random allocation to two sequences. The strength of this design

is usually considered to be an increase in statistical power, as the patient is serving as his/her own control. Power calculations performed prior to the study based on pilot data from children from the same population and of the same age showed that a minimum of 28 patients in each group was needed to identify a 25% reduction in tooth-pulp pain sensitivity for α = 0.05 and β = 0.80. Power calculations also showed that approximately 200 individuals in each group would be necessary to obtain the same power in a parallel group design. Recruiting children of 12–15 years for at study like the present proved to require considerable effort and time. Furthermore, it required complicated negotiations with authorities to obtain the required

approval for the study. Thus, any reduction in number of subjects needed ifenprodil can save considerable resources. In spite of the fact that N2O/O2 inhalation is commonly seen as a successful method to obtain acceptance of restorative treatment in children and adolescents, the present study has not been able to show any analgesic effect on tooth-pulp pain sensitivity, but did find a 20% reduction in pressure-induced pain of the jaw muscles, Thus, the success of N2O/O2 inhalation in restorative paediatric dental care must also be caused by other factors. First of all, the sedative effect would result in a more relaxed patient, who would react later – and maybe less precisely – on painful treatment. This is supported be the finding that the discomfort of the children from the two experimental tests was not influenced by the inhalation of N2O/O2. Secondly, many of the other unpleasant stimuli, the patient received during restorative treatment, like muscle discomfort from having to keep the mouth open for a long time, etc. may be less disturbing when sedated.