Objectives We evaluated patient preference and reported levels of anxiety and discomfort of participants treated with a new needle-free electric motor-driven device vs. conventional local anaesthetic for dental extractions in a proof-of-principle study. Healing and response of gingival tissues to injection were also evaluated at 1, 3- and 7-days post-procedure.

Methods After informed consent, eight participants who required bilateral maxillary extractions were included in the trial. The side and order of placement for the needle-free and conventional anaesthetic were randomized. The same operator delivered anaesthesia and ensured teeth were anaesthetized on both sides. Another operator, unaware of order and type of anaesthesia placed, performed the extractions.

Results Participant's average discomfort scores were low for both techniques, and lower for the needle-free injection at all timepoints. Needle-free local anaesthesia was the preferred technique by most participants at most timepoints. The average volume of anaesthetic dispensed was similar between techniques. Successful anaesthesia with the needle-free device was achieved in 6 out of 8 participants. Healing of the extraction sockets and adjacent oral mucosa progressed normally for all participants, with no evidence of infection, trauma or hematoma in the injection sites of the test and conventional sides.

Conclusions The needle-free local anaesthetic technique investigated achieved sufficient anaesthesia for tooth extractions in the maxilla in 75% of the subjects. A larger clinical trial is needed to further validate the technique tested and to investigate whether needle-free local anaesthesia can be successfully applied to the provision of restorative therapy.

Clinical significance The results of this study can be used by clinicians treating patients who suffer from dental anxiety and needle-phobia.