Why Are Warm LED Headlights an Excellent Dental Illumination Option?

ErgoPractice News – September 2022
By Jin Chang PhD
jchang@surgitel.com

Summary

The main purpose of clinical illumination is to help clinicians see anatomical features which are unique to their procedures. Recognizing that one style of LED light cannot meet illumination requirements for various clinical cases, SurgiTel has been offering four LED colors: warm (about 3000K), neutral (about 4000K), type 1 cool (about 5700K), and type 2 cool (about 6500K). Warm and neutral (or natural) LED lights are designed for dental or cosmetic procedures and cool LED lights are for surgical applications. Since teeth reflect blue light effectively, dental professionals are facing more blue light hazards from cool LED lights which have strong blue spectral peaks. If you have been using cool LED lights, you should seriously consider warm LED lights (about 3000K) as your dental headlight. This issue will show the advantages of warm LED lights over cool LED lights.

LED Lights and Thermal Light Sources

LED lights have been replacing thermal light sources such as halogen lights (about 3000K) and xenon arc lights (about 6200K). Thermal lights have continuous spectral distributions, but LED lights have two spectral bands: a “Blue” spectral band and a “Green-Red” spectral band. Corrected color temperatures (CCT) of LED lights are created by adjusting the strength of the blue band peak against the strength of the green-red band peak.

Before LED lights were available, halogen lights were used as the primary dental illumination and xenon arc lights as the primary surgical illumination. The color rendering index (CRI) of both halogen lights and xenon lights is almost 100. The CRI of cool LED lights is significantly lower than the CRI of either halogen lights or xenon arc lights.

Spectral Curves/Distribution

Figure 1 shows spectral curves of warm LED light, halogen light, an example of cool LED lights, and daylight. Figure 1 also shows the blue light hazard function and visual efficiency function (sensitivity to wavelengths also called photopic response) of the eyes.  Light under the blue light hazard function can damage the retina with extended exposure. Most manufacturers used cool LED headlights which simulate the color temperature (6500K) of daylight, but the actual spectral distribution of cool LED lights is totally different from that of daylight. The CRI of daylight is 100, but the CRI of cool LED lights is significantly lower than 100 and distorts the color of objects due to the strong blue spectrum.

The spectral distribution of warm LED lights is very close to the spectral distribution of halogen lights over the visual spectral region. It is noted that the main dental illumination prior to the use of cool LED lights was the halogen lights which have almost 100 CRI.  The blue spectral peak of cool LED lights is significantly stronger than the green-red spectral peak and the red spectrum of cool LED lights is very weak which is the main deficiency of cool LED lights. Cool LED lights not only distorts the color of teeth but also creates a higher risk of blue light hazard. As shown in Figure 2, most LED headlights available today are cool or extremely cool.¹ Only SurgiTel has been offering true warm and neutral LED lights.

LED Headlights as Dental Illumination

To be effective dental illumination, LED headlights should meet two basic requirements. The first requirement is to help dental professionals see the essential features of teeth and tissues well. The second requirement is to minimize the potential blue light hazard which may increase the potential risk of age-related macular degeneration (AMD).^2-6

There are three reasons why dental professionals should consider replacing their current “cool LED” light with a “warm LED” as their LED headlight.

1. The first reason is that the color accuracy achieved with warm LED light is better than the color accuracy achieved with cool LED lights because the CRI of warm LED lights is higher than cool LED lights. If you are using a cool LED headlight, you may not see the true color of teeth and tissues because the strong blue light of cool LED lights distorts the color of objects such as teeth and tissues.
2. The second reason is that warm LED light has the lowest blue spectral peak like halogen lights and thus it is the safest for the eyes. A recent article shows that some cool LED headlights have more blue light hazard than dental curing lights.⁷ The extended exposure to strong blue light may increase the risk of AMD. Figure 3 shows images seen through normal healthy eyes and eyes with AMD. If you want to protect your eyes from potential blue light hazard, you should seriously consider warm LED lights which may also offer better color accuracy.
3. The last reason is that you may not need an orange filter for composite procedures. You can perform composite procedures under good illumination without losing the color.

It is noted that if you have used cool LED lights for many years, you may not know the true color of objects because cool LED lights distort the color of objects.

Evaluation of Your Current LED Lights

It can be very difficult to estimate the degree of coolness of the LED beams you are using. The best way is to compare images under the illumination of your current LED headlight with images under the illumination of SurgiTel neutral or warm LED headlights which have an excellent CRI. The SurgiTel True Color neutral LED light has been used as the reference LED light.

If you contact us, we can help you evaluate your current LED headlights by comparing it with our True Color neutral LED headlights which can be used as the reference LED headlight.

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References

1. Price, Richard. Ratio of Blue Spectral Band Peak over Green-Red Spectral Band Peak of Various LED Headlamps, Private Communication, May 2021.
2. Stamatacos, Catherine, and Janet L Harrison. “The Possible Ocular Hazards of LED Dental Illumination Applications.” The Journal of the Tennessee Dental Association 93, no. 2 (2013): 25–29. https://pubmed.ncbi.nlm.nih.gov/24611218/.
3. The Blue Light Hazard in Medicine and Dentistry. PriceCuringLab. YouTube, 2012. https://www.youtube.com/watch?v=VfCmL4Kz2iw.
4. Chang, Jin. “Is Your LED Headlight Type Safe For Your Eyes?” SurgiTel. ErgoPractice News, November 2018. https://www.surgitel.com/is-your-led-headlight-type-safe-for-your-eyes.
5. “OPINION of the French Agency for Food, Environmental and Occupational Health & Safety on the ‘Effects on Human Health and the Environment (Fauna and Flora) of Systems Using Light-Emitting Diodes (LEDs).’” anses. anses, April 5, 2019. https://www.anses.fr/en/system/files/AP2014SA0253EN.pdf.
6. Fluent, Marie T., Jack L. Ferracane, James G. Mace, Anjali R. Shah, and Richard B. Price. “Shedding Light on a Potential Hazard.” The Journal of the American Dental Association 150, no. 12 (December 2019): 1051–58. https://doi.org/10.1016/j.adaj.2019.08.012.
7. Price, Richard B., Daniel Labrie, Braden Sullivan, and David H. Sliney. “The Potential ‘Blue Light Hazard’ from LED Headlamps.” Journal of Dentistry 125 (August 10, 2022): Article 104226. https://doi.org/10.1016/j.jdent.2022.104226.