Very many patients are frightened of or anxious about dental treatment12). One major reason is that the treatment site is in the facial area itself, so that the treatment can be seen and remembered. Pain and fear they have felt during previous dental treatment frequently become imprinted, and many patients feel stressed prior to treatment. In wisdom tooth extraction, even if the patient’s vision is obscured, they are required to keep their mouths open for a certain period, and the metallic screech of the drill and the unpleasant smell during drilling all contribute to a high level of stress. In practice, even if adequate analgesia is provided by local anesthesia, patients still experience mental and physical stress during the procedure. In some cases, this may even lead to dental phobia. The methods used to relieve this anxiety and fear of treatment include sedation by inhalation anesthesia or intravenous anesthesia, as well as the use of oral tranquilizers. However, drug administration may cause side effects or be contraindicated, and is thus not suitable for all patients.
In a previous study, we demonstrated that the use of VR decreased anxiety and fear of surgical treatment under local anesthesia both subjectively and objectively6,7). In our objective assessment using heart rate variability (HRV)13,14), we showed that, although patients were in a state of arousal preoperatively, with sympathetic nervous system activity predominating, experiencing VR with images designed to induce relaxation restored balance with parasympathetic nervous activity, and they became relaxed.
VR is currently in use in several medical fields15–17). It consists of three elements: three-dimensional presence, autonomy, and real-time interaction. It can thus transport the user into a different experience by stimulating all the senses, not just sight18). The employment of VR techniques such as the one used in this study does not require the use of specific drugs and involves almost no physical invasion. A further advantage is that, because it requires neither drugs nor expensive equipment, it does not entail any running costs. Our previous results also demonstrated that it can be used by a wide range of age groups, including older people. The results of the present study showed that the content of the VR presentation modulated its effect on decreasing anxiety. It was also demonstrated, both subjectively and objectively, that a video game presentation that required thought reduced pain. Another study has reported that the use of VR during burn treatment enables the dose of analgesics to be reduced, a finding that supports our results19–21). Although there is individual variation in its effects on reducing anxiety and pain, the effects appear to be dependent on the individual’s level of concentration while experiencing the presentation. This suggests that the viewer’s preferences may be a major factor in the selection of a presentation. The physiological mechanism that diminishes pain during concentration on a presentation has yet to be clearly identified. We intend to use near-infrared spectroscopy (NIRS) or dynamic magnetic resonance imaging (MRI) to measure changes in cerebral perfusion to demonstrate the extent to which these effects can be obtained in future.
One point that warrants attention in the experience of VR is cybersickness22–24). This condition is known to occur when the viewer’s gaze follows text or images moving rapidly on the screen, which results in headaches, nausea, and feelings of unsteadiness. There are calls for particular care to be taken with children25,26). In this study, even the video game presentation that we produced did not cause any patient to complain of cybersickness-like symptoms. As the age range expands, however, care will be required in the future to check that cybersickness does not occur while experiencing VR.
A head-mounted display is required to experience VR, but the thickness and heaviness of these displays is an impediment for both operator and patient. It is hoped that smaller, lighter devices will be developed in the future.
In a previous study, we showed that most patients who used VR during a surgical procedure expressed the wish to use VR during other such procedures in the future. This suggested that VR is readily accepted by patients and can fill a need as a sedative device. The recent universal adoption of smartphones and the development of the games industry have increased the proportion of people who have experienced VR, and its introduction into medicine should be relatively easy. To enable its use by a wide range of age groups, including older people, in the future it will be necessary to choose presentations based on age and individual preferences. The evolution of VR, augmented reality (AR), mixed reality (MR), and cross reality (XR) is proceeding apace, as is that of image technology27). If these issues can be resolved, VR has the potential to become a medical assistive device not only for resolving anxiety, but also for alleviating pain during dental treatment.