Effects of Green Color Exposure on Stress, Anxiety, and Pain during Peripheral Intravenous Cannulation in Dental Patients Requiring Sedation by Takemiura,Kido, Kawan et al. 2021

This randomized, controlled, single-center, cross-over clinical trial was conducted between April 2019 and March 2020 at the Kanagawa Dental University Hospital, Yokosuka, Japan. Adult patients (aged older than 20 years) undergoing IV sedation for dental treatment were included. The patients underwent two color exposures with glasses (Color Therapy Glasses, GloFX, FL, USA) on two different days: wear of green-colored glasses or clear-color glasses (as control). Using a computer-generated randomization method, the participants were randomly allocated to PIC with green color exposure (green group) or clear color exposure (clear group) first, and then crossed over to the other type of glasses after a 4-week washout period.

This is an experimental study that was conducted in a clinical setting. This experiment took place at Kanagawa Dental University Hospital in Yokosuka, Japan, between April 2019 and March 2020. The participants were adults older than 20 years old and were undergoing IV sedation for dental treatment. The participants were randomly assigned to either treatment (green-coloured glasses) or placebo (clear-coloured glasses). It seems like the participants also tried the other type of glasses after 4 weeks?

Although local anesthesia injection, local anesthetic cream, and vapocoolant spray are widely reported to reduce pain during PIC [9,10,11], these strategies target pain but do not address anxiety and fear. Furthermore, they are not often used because they are expensive, time-consuming, and prone to causing allergic reactions or vasoconstriction and may be hard to use [5,12,13]. Therefore, simple, safe, easy-to-use, non-invasive, cost-effective, and reusable methods have been recommended [14]. Ibrahim et al. recently reported that exposure to green light resulted in antinociception and anti-hyperalgesia in rats and depended on engagement of the visual system [15]. In that study, green light exposure also induced an anxiolytic effect. Moreover, the same research group showed that green light improved pain and quality of life in patients with fibromyalgia and migraine [16,17]. Therefore, green color exposure before a medical procedure might reduce pain and anxiety during PIC.

Anesthesia does not assist with the mental health associated with the procedure. Anesthetics are not commonly used as it is expensive, time-consuming or have other factors such as allergic reactions. The goal of the study is to find a method that is safe, simple, cost-effective and non-invasive.
From a previous study, green light seems to have an anxiolytic effect, which means that it has properties to treat anxiety, panic attack or other short-term mental health issues. So, the authors are hoping that green light might be the non-invasive procedure that can reduce pain and anxiety during peripheral intravenous cannulation (PIC) aka dental surgery.

The intensity of anxiety during PIC was less with green color exposure than with clear color exposure in 18/23 subjects, although it was not significant (median VAS-A, 9.5 versus 21.0; p = 0.109, Mann–Whitney U-test, Figure 3A). Similarly, the intensity of pain during PIC was significantly less in the green group than in the control group in 19/24 subjects (median VAS-P, 17.0 versus 50.0; p = 0.011, Mann–Whitney U-test, Figure 3B).

The result was that anxiety did drop with green colour exposure vs no colour exposure in 18 participants over a total of 23. However, it was not a significant finding. 19 participants found green colour exposure helped reduce pain.

The present study had several limitations. First, all study participants had a known history of fear or anxiety about dental treatment. Therefore, they might have been more sensitive and apprehensive about the prospect of a painful medical procedure, resulting in stronger responses. A further study might be needed to consider the patient characteristics. Second, we did not investigate the mechanism of the effects of green color exposure. Finally, we did not examine the effects of other colors. We are presently embarking on a study of which color is best for reducing anxiety and pain during PIC.

There were errors, bias, and limitations in the study. All the participants have a mental health history before the dental treatment, which could skew the response, as they could find the anxiety or pain relatively higher than that of normal participants. They did not investigate the mechanism of the green light exposure. They also did not try other colours to see if the concept of “green” was the result of the reducing effects.

As the study mentioned, colour association with mental health would be a follow-up. In addition, to continuously finding a method of non-invasive experiment that can reduce pain and anxiety.

There were many jargons and short-form terminology associated with dentistry. Although the method section was clear and concise, the results were poorly written and presented. There did not seem to be much of a finding.