ORIGINAL RESEARCH |
https://doi.org/10.5005/jp-journals-10015-2341 |
Effect of Brainwave Entrainment on Perception of Anxiety during Dental Treatment: A Pilot Study
1,3,5Department of Conservative Dentistry, SRM Kattankulathur Dental College and Hospital, Chengalpattu, Tamil Nadu, India
2Department of Oral and Maxillofacial Surgery, SRM Kattankulathur Dental College, Chengalpattu, Tamil Nadu, India
4Department of Periodontics, SRM Kattankulathur Dental College and Hospital, Chengalpattu, Tamil Nadu, India
Corresponding Author: Vivek Narayanan, Department of Oral and Maxillofacial Surgery, SRM Kattankulathur Dental College, Chengalpattu, Tamil Nadu, India, Phone: +91 9444360303, e-mail: rekham@srmist.edu.in
Received: 03 November 2023; Accepted: 06 December 2023; Published on: 31 January 2024
ABSTRACT
Background: Anxiety impacts both physical and mental health with symptoms including nervousness, palpitations, sweating, and dizziness, thereby affecting cardiovascular, respiratory, digestive, and nervous systems. Brainwave entrainment (BWE) is the capacity of the brain to synchronize its own frequencies with the rhythm of an externally applied stimulus. Patients undergoing dental treatment experience increased anxiety both preoperatively and intraoperatively. This, in turn, may lead to increased perception of pain as well as instability of vital signs throughout the procedure. There are numerous nonpharmacological adjuvants employed for management of dental anxiety; however, this study is an attempt to assess the effect of BWE on anxiety in patients undergoing root canal therapy.
The purpose of this study was to assess the effect of BWE on systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) values both before and during root canal treatment in population experiencing moderate to severe anxiety assessed using Corah’s Dental Anxiety Scale.
Materials and methods: Forty participants were included in this pilot study and were divided into four groups (three entrainment groups and one control group). The three entrainment groups include alpha (10 Hz), theta (7 Hz), and delta (1 Hz) groups subjected to audiovisual entrainment in the corresponding frequencies. All participants were subjected to 10 minutes of preoperative entrainment except for the control group. The second entrainment session was applied, following administration of local anesthesia and rubber dam isolation, for 10 minutes following which the intratreatment vital sign values were recorded. In case of control group, no entrainment sessions were applied but simply the vital signs were recorded 10 minutes before and after initiation of treatment (preoperative and intraoperative, respectively).
Results: Delta entrainment group exhibited significantly lower HR values both pre- and intraoperatively (p < 0.05). There were no significant differences with regard to SBP and DBP values.
Conclusion: Brainwave entrainment (BWE) can be considered an effective nonpharmacological aid for management of anxiety in patients requiring dental treatment.
How to cite this article: Mani R, Narayanan V, Venkatesh V, et al. Effect of Brainwave Entrainment on Perception of Anxiety during Dental Treatment: A Pilot Study. World J Dent 2023;14(12):1032–1036.
Source of support: Nil
Conflict of interest: None
Keywords: Alpha, Audiovisual stimulation, Delta, Dentistry, Rainwave entrainment, Theta
INTRODUCTION
Dental care, in general, is perceived to be invasive by the patients. Dental anxiety is the general term used to describe a wide spectrum of emotions vacillating from mild apprehension to extreme fear or anxiety. Recent studies demonstrate an increased demand for sedation during dental procedures, even during routine root canal treatments.1,2 Studies also report that anxiety can complicate the dental procedure leading to increased pain perception and lack of patient compliance.1,3,4
In a dental office, patients are continuously exposed to the noises of dental drills, sharp metallic instruments, disturbing rubber dams, and associated suffocation fear. Huh et al., in 2015, reported that about 51% of patients preferred to undergo root canal procedures under sedation making it more acceptable to patients.5 However, sedation has its own risks and benefits. In sedation, the amount of drug reaching the central nervous system is inconsistent because of the variability in absorption.
Brainwaves are repeated and rhythmic oscillating electrical voltages in the brain detected using electroencephalography (EEG). The EEG waves are classified into four types depending on the frequencies delta (<3.5 Hz), theta (4–7.5 Hz), alpha (8–13 Hz), and beta (>13 Hz).6 Alpha rhythm is characterized by a frequency of 8–13 Hz over the posterior part of the head particularly the occipital areas, during wakefulness particularly with eyes closed. These waves are blocked by attention particularly physical or mental effort. Theta waves with a frequency of 4–7.5 Hz are prominently seen in the frontocentral region associated with the onset of drowsiness and disappearance of alpha. While beta waves represent a busy and active state of mind, delta waves are prominent during sleep and dreaming.
Recent neurofeedback studies have developed and confirmed the idea that brain can be entrained to a particular frequency by auditory, visual, audiovisual, and tactile stimulation (Jensen et al. 2013). Auditory and visual entrainment results in an immediate increase in the applied frequency throughout the cortex.7,8 Entrainment has found numerous applications in reducing the perception of acute and chronic pain, for cognitive improvement in neurodegenerative disorders like Alzheimer’s, for sleep and mood improvement, etc.9–13
Findings to date suggest that brainwave entrainment (BWE) is an effective therapeutic tool. People suffering from cognitive functioning deficits, stress, pain, headache/migraines, premenstrual syndrome (PMS), and behavioral problems have benefited from BWE. Opartpunyasarn et al. reported successful use of binaural beat auditory entrainment for management of anxiety in patients undergoing fiberoptic bronchoscopy. However, there is no substantial data on the effect of combined audiovisual entrainment on dental anxiety. Therefore, this study tried to assess the effect of BWE on the perception of anxiety during dental treatment.
MATERIALS AND METHODS
Methodology
This randomized controlled study was approved by the Institutional Ethics Committee of SRM Medical College Hospital and Research Centre, Kattankulathur, Tamil Nadu, India. Forty consenting ASA 1 category participants, aged between 20 and 40 years requiring root canal treatment for maxillary anterior teeth, were included in this pilot study. People with history of epilepsy, head injury, psychiatric illness, systemic diseases, currently using any drugs or alcohol and pregnant women were excluded from the study. The first author performed all root canal procedures under local anesthesia with 2% lignocaine hydrochloride while the fifth author applied the entrainment and recorded the vital signs. The procedure duration did not exceed 30 minutes. All participants completed Corah’s Dental Anxiety Scale before the randomization process. Only those participants with anxiety values ≥9 on the scale were included in the study.
The participants were then randomly allocated to one of the four groups (n = 10) (three entrainment groups and one control group) using computer-generated randomization. The three entrainment groups include alpha (10 Hz), theta (7 Hz), and delta (1 Hz) groups subjected to audiovisual entrainment. The entrainment was applied using an audiovisual device (David Delight plus audiovisual device for entrainment, manufactured by Mind Alive Inc. Edmonton, Alberta, Canada). The device consists of a Tru-Vu Omniscreen Multi-Color Eyeset and a headset with five inbuilt sessions of different frequencies. Turning on a session produces the corresponding frequency to be played in the headset while feeble light-emitting diode (LED) lights blink in synchronizing with the headset frequency. Therefore, the participants received a combined audiovisual stimulation, where the auditory stimulation was rendered using a headset and visual stimulation, of the corresponding frequency, via LED lights falling over the participants’ closed eyes. When participants receive this combined auditory and visual stimulation, with eyes closed, the corresponding session frequency starts to predominate in the patient’s brain. The device was standardized and calibrated using EEG on five participants. It was shown that the time taken for the entrainment frequency to predominate in EEG was 2–3 minutes. In the present study, the following frequencies were applied to the experimental groups—alpha (10 Hz), theta (7 Hz), and delta (1 Hz).
All participants underwent 10 minutes of preoperative entrainment, except for the control group, following which the preoperative vital signs, namely systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) values were recorded. This was followed by administration of local anesthetic and rubber dam isolation. The second entrainment session was then applied for 10 minutes during the procedure and the intratreatment vital signs were recorded at the end of the session. In case of the control group, no entrainment was applied but the vital signs were assessed after the patient waited for 10 minutes before initiation of treatment and 10 minutes after the beginning of treatment (preoperative and intraoperative, respectively). An automatic blood pressure monitor (OMRON Healthcare India Pvt Ltd) was used in the study to measure the values of SBP, DBP, and HR. The root canals were obturated either on the same appointment or on a subsequent appointment based on the vitality status or pathology associated with the tooth.
RESULTS AND STATISTICAL ANALYSIS
Out of the total 40 patients included in the study, 23 were men and 17 were women, all aged between 20 and 40 years of age. Descriptive analysis results of SBP, DBP, and HR of all variables, Preoperative and intraoperative times are presented in Tables 1 to 3 and Figures 1 to 3, respectively.
| Preoperative | |||||
|---|---|---|---|---|---|
| Variable/group | Control | Delta | Alpha | Theta | p-value |
| Mean ± standard deviation (SD) | Mean ± SD | Mean ± SD | Mean ± SD | ||
| SBP | 112.8 ± 18.16 | 114.8 ± 4.66 | 124.6 ± 10.33 | 120.8 ± 15.29 | 0.486 |
| DBP | 73.6 ± 12.22 | 74.2 ± 3.63 | 75.8 ± 4.92 | 80 ± 15.08 | 0.753 |
| HR | 83.2 ± 10.33 | 57.8 ± 1.79$ | 76.6 ± 3.44 | 82 ± 4.95 | <0.001* |
$, significantly differed from control, alpha, and theta groups; *, significantly differed between groups
| Intraoperative | |||||
|---|---|---|---|---|---|
| Variable/group | Control | Delta | Alpha | Theta | p-value |
| Mean ± SD | Mean ± SD | Mean ± SD | Mean ± SD | ||
| SBP | 109.6 ± 22.68 | 115.8 ± 3.03 | 123.6 ± 6.07 | 124.4 ± 16.38 | 0.347 |
| DBP | 67.2 ± 12.66 | 74.4 ± 4.04 | 77.4 ± 3.78 | 80.4 ± 14.84 | 0.239 |
| HR | 76.8 ± 9.96 | 64 ± 1.87$ | 85.2 ± 9.55 | 83.4 ± 8.05 | 0.003* |
$, significantly differed from alpha to theta groups; *, significantly differed between groups
| Overall | |||||
|---|---|---|---|---|---|
| Variable/group | Control | Delta | Alpha | Theta | p-value |
| Mean ± SD | Mean ± SD | Mean ± SD | Mean ± SD | ||
| SBP | 111.2 ± 19.44 | 115.3 ± 3.74$ | 124.1 ± 8.01 | 122.6 ± 15.06 | 0.108 |
| DBP | 70.4 ± 12.2 | 74.3 ± 3.62 | 76.6 ± 4.22 | 80.2 ± 14.11 | 0.168 |
| HR | 80 ± 10.14 | 60.9 ± 3.7@ | 80.9 ± 8.14 | 82.7 ± 6.34 | <0.001 |
$, significantly differed from the alpha group; @, significantly differed from control, alpha, and theta groups
Fig. 1: Preoperative and intraoperative HR values. Delta group exhibiting minimal values
Fig. 2: Preoperative and intraoperative SBP values
Fig. 3: Preoperative and intraoperative DBP values
Table 2 shows mean of intraoperative values (SBP, DBP, and HR). The mean intraoperative SBP values obtained were 109.6 (control), 115.8 (delta), 123.6 (alpha), and 124.4 (theta), and the mean intraoperative DBP values include 67.2 (control), 74.4 (delta), 77.4 (alpha), and 80.4 (theta). The mean HR values obtained were 76.8 (control), 64.0 (delta), 85.2 (alpha), and 83.4 (theta), and again the difference in HR values with respect to the delta group was found to be statistically significant.
Table 3 shows mean of pre- and intraoperative values (SBP, DBP, and HR) with lowest mean value for delta group (60.9) for HR with statistical significance.
Figures 1 to 3 depict the mean of pre- and intraoperative values of HR, SBP, and DBP, respectively.
No statistically significant differences were observed between the study groups with regard to SBP and DBP both pre- and intraoperatively. However, delta entrainment showed significantly lower HR values in both pre- and intraoperative times (p < 0.05)
DISCUSSION
Brainwave entrainment (BWE) is a physiological synchronization of the dominant waves of the brain with the frequency of an externally applied episodic stimulus. The external stimulus can be auditory in the form of monoaural beats, binaural beats, or isochronic tones. Visual stimulation is applied as episodic blinking light in a preset frequency. Physical stimulation is applied by exertion of periodic vibrations over a nerve or a muscle. Entrainment applied by the combination of the above methods is usually more effective.7
Dentistry commonly uses a number of auditory and visual devices, encompassing instrumental music, relaxing music and distracting videos for behavior modulation and anxiety control. Most of these methods work on a psychological distraction method while BWE produces physiological relaxation by altering the brainwaves. Entrainment works by transcending the existing brainwaves to lower frequencies which are more relaxing in nature, thereby reducing anxiety. For this reason, BWE is particularly effective in management of mental afflictions as in case of drug addiction, depression, anxiety, sleep disorders, pain control, etc. BWE has also been employed for improvement of mental skills so as to increase focus, concentration, attention-deficit hyperactivity disorder (ADHD), creativity, etc.7
Audiovisual entrainment with alpha range has been shown to produce an immediate increase in the brainwaves oscillating in the alpha frequency throughout the cortex.8,9 The other regions of brain also tend to fall into a lock step with the stimulated cortex resulting in entrainment.9,14–19 Visual entrainment using alpha frequency has been shown to produce responses primarily in the visual cortex,1,20 and cortical activity modulations usually are brought forth throughout the cortex.8,17
In our study, audiovisual entrainment was applied using David Delight plus audiovisual device (Mind Alive Inc. Edmonton, Alberta, Canada). Visual stimulation to the entrainment groups was enabled by applying LED light over closed eyes21 combined with auditory stimulation applied via headset. Audiovisual simulation was not applied to the control group as any attempt to close the eyes may increase the alpha frequency by default. In this study, only the pre- and intraoperative vital sign values were assessed because studies have reported postoperative anxiety to be minimal compared to preoperative levels22 and also it is the intraoperative fear that interferes with the treatment complicating the outcome.
Chaieb et al. showed that stimulation with monoaural beat can reduce state anxiety values.23 Sanchez et al. applied 10 Hz and 20 Hz photic stimulation and assessed the effect on stress reduction during therapeutic procedures. Verbal report from the participants revealed a highly relaxed state following stimulation. Stress and anxiety assessed using State-Trait Anxiety Inventory (STAI) scale revealed an average reduction of 20%.24
To the best of the author’s knowledge, this study is the first of its kind to assess the effect of audiovisual BWE on anxiety during dental treatment. This pilot study was intended to address the feasibility issues when employing audiovisual entrainment devices during dental procedures. The main limitation of the study is the limited sample size and therefore more studies in this regard are needed to ascertain the effectiveness of BWE devices in dentistry.
CONCLUSION
Audiovisual BWE appears to be a novel and promising tool in reducing anxiety in patients undergoing dental procedures. In particular, delta waves with the lowest frequencies seem to reduce anxiety more effectively than the other entrainment groups. BWE can help in both ways by reducing patients’ mental afflictions as well as by enhancement of brain function. However, the studies on the therapeutic application of BWE are sparse and hence further research is needed.
ORCID
Vivek Narayanan https://orcid.org/0000-0002-1454-3984
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