Effect of high-intensity irradiation from dental photopolymerization on the isolated and superfused vertebrate retina

The potential 'Blue Light Hazard' from LED Headlamps

Many dental personnel use light-emitting diode (LED) headlamps for hours every day. The potential retinal 'blue light hazard' from these white light headlamps is unknown.

METHODS

The spectral radiant powers received from direct and indirect viewing of an electronic tablet, an LED curing light, a halogen headlamp, and 6 brands of LED headlamps were measured using integrating spheres attached to fiberoptic spectroradiometers. The spectral radiant powers were measured both directly and indirectly at a 35 cm distance, and the maximum daily exposure times (t_MAX) were calculated.

RESULTS

The headlamps emitted very different radiant powers, emission spectra, and color temperatures (K). The total powers emitted at zero distance ranged from 47 mW from the halogen headlamp to 378 mW from the most powerful LED headlamp. The color temperatures from the headlamps ranged from 3098 K to 7253 K. The t_MAX exposure times in an 8-hour day when the headlamps were viewed directly at a distance of 35 cm were: 810 s from the halogen headlamp, 53 to 220 s from the LED headlamps, and 62 s from the LED curing light. Light from the LED headlamps that was reflected back from a white reference tile 35 cm away did not exceed the maximum permissible exposure time for healthy adults. Using a blue dental dam increased the amount of reflected blue light, but t_MAX was still greater than 24 hours.

CONCLUSIONS

White light LED headlamps emit very different spectra, and they all increase the retinal 'blue light hazard' compared to a halogen source. When the headlamps were viewed directly at a distance of 35 cm, the 'blue light hazard' from some headlamps was greater than from an LED curing light. Depending on the headlamp brand, t_MAX could be reached after only 53s. The light from the LED headlamps that was reflected back from a white surface that was 35 cm away did not exceed the maximum permissible ocular exposure limits for healthy adults.

CLINICAL RELEVANCE

Reflected white light from dental headlamps does not pose a blue light hazard for healthy adults. Direct viewing may be hazardous, but the hazard can be prevented by using the appropriate blue-light-blocking glasses.

Knowledge and Attitude of Dental Clinicians towards Light-Curing Units: A Cross-Sectional Study

Objectives

Light curing is crucial when applying composite resin restorations. Complete polymerization of the resin depends on delivering adequate light energy to it. Dental clinicians may be unaware of the importance of proper light-curing techniques. This study aimed at evaluating and comparing the level of knowledge of general practitioners (GPs) and specialists (SPs) regarding light-curing units.

Materials and Methods

An electronic survey was conducted online among GPs and SPs of various specialties, working in the governmental sector in Riyadh, Saudi Arabia. Collected data were analyzed for statistical significance.

Results

310 dentists were included in the study. Nearly half of the GPs (45.9%) and more than half of SPs (56.8%) use light-emitting diode (LED) type light-curing units (LCUs). 36.9% of GPs and 29.6% of SPs were unsure about the type of LCUs they use in their dental clinics. 10.8% of GPs and 8.5% of SPs knew the proper term of the power output of LCU. 52.2% of the GPs and 55.7% of SPs were wrong about advancements in technology of LED LCUs. Regarding the use of radiometer, 48.2% of SPs and 35.1% of GPs had responded wrongly, and 37.7% of SPs and 52.3% of GPs were not familiar with the device, showing a statistical significance (p=0.040). There was no statistical significance observed in the responses pertaining to their years of experience, expected for two questions.

Conclusion

Both GPs and SPs displayed inadequate knowledge regarding the use of LCUs. Further educational programs are recommended to spread awareness about the handling of LCUs among dental clinicians.

Shedding light on a potential hazard: Dental light-curing units

BACKGROUND

Dental light-curing units (LCUs) are powerful sources of blue light that can cause soft-tissue burns and ocular damage. Although most ophthalmic research on the hazards of blue light pertains to low levels from personal electronic devices, computer monitors, and light-emitting diode light sources, the amount of blue light emitted from dental LCUs is much greater and may pose a "blue light hazard."

METHODS

The authors explain the potential risks of using dental LCUs, identify the agencies that provide guidelines designed to protect all workers from excessive exposure to blue light, discuss the selection of appropriate eye protection, and provide clinical tips to ensure eye safety when using LCUs.

RESULTS

While current literature and regulatory standards regarding the safety of blue light is primarily based on animal studies, sufficient evidence exists to suggest that appropriate precautions should be taken when using dental curing lights. The authors found it difficult to find on the U.S. Food and Drug Administration database which curing lights had been cleared for use in the United States or Europe and could find no database that listed which brands of eyewear designed to protect against the blue light has been cleared for use. The authors conclude that more research is needed on the cumulative exposure to blue light in humans. Manufacturers of curing lights, government and regulatory agencies, employers, and dental personnel should collaborate to determine ocular risks from blue light exist in the dental setting, and recommend appropriate eye protection. Guidance on selection and proper use of eye protection should be readily accessible.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The Centers for Disease Control and Prevention Guidelines for Infection Control in the Dental Health-Care Setting-2003 and the Occupational Safety and Health Administration Bloodborne Pathogen Standard do not include safety recommendations or regulations that are directly related to blue light exposure. However, there are additional Occupational Safety and Health Administration regulations that require employers to protect their employees from potentially injurious light radiation. Unfortunately, it is not readily evident that these regulations apply to the excessive exposure to blue light. Consequently employers and dental personnel may be unaware that these Occupational Safety and Health Administration regulations exist.

Ocular hazards of curing light units used in dental practice - A systematic review

Objective

To examine the literature and summarize studies that describe the potential ocular hazards that are posed by different systems of light curing units mainly used in the dental clinics, to ensure the safety of the operator, patient and the auxiliary staff in the dental clinic.

Methods

This systematic review was reported and conducted according to the PRISMA guidelines. The online databases PubMed and Google Scholar were used for data search. MeSH terms were used for PubMed search. Randomized controlled clinical trials, original studies and in-vitro studies conducted up to 2018 in English language were included in the review. Eight articles were included in the study after application of eligibility criteria, all of which were in accordance to the review protocol.

Results

The total wavelength dose received can cause Ocular damage which suggest that light intensity is correlated to the duration required to cause a certain level of damage, and we can substitute the long light exposure by using of a lower intensity light.

Conclusion

This review concludes that blue light poses maximum risk to cause retinal degeneration based on the evaluated studies. Most of the studies recommend the use of protective eyewear in order to limit exposure of the patient, operator and assistant to the LCUs. It is not advisable to stare directly into the light source and the recommended safe exposure times and distances for patient, operator and assistant must be strictly adhered to in the dental practice.

Evaluation of Eye Protection Filters Used with Broad-Spectrum and Conventional LED Curing Lights

Abstract The high irradiance and the different emission spectra from contemporary light curing units (LCU) may cause ocular damage. This study evaluated the ability of 15 eye protection filters: 2 glasses, 1 paddle design, and 12 dedicated filters to block out harmful light from a monowave (HP-3M ESPE) and a broad-spectrum (Valo, Ultradent) LED LCU. Using the anterior sensor in the MARC-Patient Simulator (BlueLight Analytics) the irradiance that was delivered through different eye protection filters was measured three times. The LCUs delivered a similar irradiance to the top of the filter. The mean values of the light that passed through the filters as percent of the original irradiance were analyzed using two-way ANOVA followed by Tukey test (a= 0.05). The emission spectra from the LCUs and through the filters were also obtained. Two-way ANOVA showed that the interaction between protective filters and LCUs significantly influenced the amount of light transmitted (p< 0.001). Tukey test showed that the amount of light transmitted through the protective filters when using the HP-3M-ESPE was significantly greater compared to when using the Valo, irrespective of the protective filter tested. When using the HP-3M-ESPE, the Glasses filter allowed significantly more light through, followed by XL 3000, ORTUS, Google Professional, Gnatus filters. The Valo filter was the most effective at blocking out the harmful light. Some protective filters were less effective at blocking the lower wavelengths of light (<420 nm). However, even in the worst scenario, the filters were able to block at least 97% of the irradiance.