Nitrous oxide found to increase dental anaesthesia success rates

nitrous oxide dental anaesthesia
Photo: Tanita Seton, Dental Stock Photos

Given that between 10 and 39 per cent of patients have reported ineffective pulpal anaesthesia, finding the correct local anaesthetic can increase confidence in dental visits and assist people in more regular oral healthcare, US researchers have found.

In a study published in Anesthesia Progress, a team at Ohio State University compared the effects of nitrous oxide/oxygen (N2O/O2) with that of room air/oxygen (air/O2) on inferior alveolar nerve block (IANB) injection pain and mandibular pulpal anaesthesia success.

At two separate appointments, approximately one week apart, a total of 105 patients either received N2O/O2 or air/O2 followed by an IANB injection. Before the injection, each patient rated the anxiety level based on the Corah dental anxiety scale. After the injection, patients were asked to rate their pain at each of three injection stages, including needle insertion, needle placement, and solution disbursement, using a visual analog scale. 

Finally, over a 60-minute period, pulpal anaesthesia was evaluated using an electric pulse tester on the mandibular first and second premolars and molars, while the canine served as the unanaesthetised control.

The researchers found an overall low anxiety rating across all patients before the procedure. They also recorded that the mean pain scores were lower for the N2O/O2 group compared with the air/O2 group, which was mild or moderate for each injection stage. The success rate of the IANB injection, creating an increased likelihood of pulpal anaesthesia, was also higher in the N2O/O2 group for all four tooth types evaluated; however, pulpal anaesthesia was not reported at 100 per cent.

“Fear of pain is the number one reason people give for not making regular visits to the dentist,” Dr Al Reader said.

“Reducing the pain of a dental injection, and having the patient experience no pain during the dental visit has always been important to the practising dentist. In our study, we found administering nitrous oxide reduced the pain of the dental injection and increased the likelihood of anesthesia. We feel these findings are important to every practising dentist.”

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