The effect of vibration on pain during local anaesthesia injections

Introduction

The “Gate Control Theory” of Melzack and Wall (1965) explains that pain signals sent up to the brain can be controlled from the level of the spinal cord. During times of pain, the application of a non-painful stimulus can activate the system by closing the gate that transmits the signals to the brain, and as a result reducing the perception of pain. The stimulation of mechanoreceptors will activate the Aβ fibers to inhibit pain signal transmission. More than 30% of cells in the brain that receive, and process sensory signals respond to inputs from the oral cavity. There have been occasions where vibration stimuli have reduced pain related to the pulp, periodontal tissues or as a pain management tool following surgery or for chronic facial pain. Optimal reduction in pain can be achieved by directly stimulating the bone on the same side as the pain with the vibrations.

Methods

To address the first study question, the experiment was carried out on 42 second year dental students at the University of Sydney in Australia. The article noted ethics approvals to carry out the study. The participants were asked to rate what they expected the level of pain to be from the injection and the actual pain from the injection on a 100mm visual analogue scale (VAS). The study used both inferior alveolar nerve blocks and maxillary infiltrations as methods. To address the second research question, 62 adult participants were selected, with inclusion and exclusion criteria noted. The procedure used randomization to have a control trial without vibrations and another set of injections using vibrations.

The results of the first experiment showed a statistical significance in the difference between anticipated pain being higher than actual pain from both types of injections. The results from the second experiment showed a statistically significant decrease in the pain perceived from the injection while using a vibration stimulus compared to without. This result was again seen in both block and infiltration types of injections across the participants.

Conclusion

Although there are other factors to be considered in the way patients perceive pain from a dental injection such as anxiety and past experiences, the results are valuable enough to be considered in general dental practice to try and reduce the pain of the injection with aims of making patients more comfortable and less anxious about receiving treatment. Further studies would be beneficial in this field capturing a larger sample size and controlling for confounding factors, but the study has potential for useful applications in improving the experience of patients attending the dentist.