Evaluation of Eye Protection Filters for Use with Dental Curing and Bleaching Lamps

Abstract

Exposure to intense radiation sources in a dental clinic necessitates the use of eye protective filters to avoid blue-light photochemical retinal hazard. We have investigated the filtering quality and assessed whether the filters protect sufficiently against retinal hazards throughout the workday. Visible light transmittance of 18 protective filters was measured. These products consisted of spectacles, stationary lamp shields, and a hand-held shield intended for use in dental clinics. Nine of the 18 tested filters had adequate filtering capacity according to today's lamp technology and exposure limit values. These filters transmitted less than 0.1% of the radiation at any wavelength between 400 nm and 525 nm. Seven of the nine filters showed transmission values below the detection limit (∼10⁻³ %) in the wavelength band between 400 nm and 500 nm. Filters of inferior quality may prove inadequate if the use and radiation intensity of the lamps further increase. Lack of protection may also occur if a filter is used to protect against emission from a lamp with properties other than the lamp for which the filter has been intended. It is of major importance that the spectacles/shields accommodate the emission from the lamp source. The suppliers of dental radiation sources should be responsible for information on the need for and proper use of eye protecters. In addition, the filters should be marked according to testing procedures appropriate for the specific use.

Keywords:

• blue-light hazard
• industrial hygiene
• optical radiation
• spectacles
• threshold limit value
• transmittance

ACKNOWLEDGMENTS

This work was supported in part by the Norwegian Directorate for Health and Social Affairs. The authors thank Coltène Whaledent, Lic Scadenta AS, Norsk Dental Depot, KerrHawe, Norway, and Ellipse-Klinikken, Oslo, Norway, for providing products to this study.

Notes

^A t_{max, filter} = maximum permissible exposure duration.

^B Measured by the method applying incident monochromatic radiation.