IADR Abstract Archives
Method to Evaluate Blue-Light Protective Filtering Devices for Light-Curing Units
Objectives: Dental light curing units (LCU)s can pose a risk of exceeding the limits specified for photochemical retinal blue-light exposure, as specified in international radiation protection guidelines (ICNIRP,2013). Protective filtering devices (PFD)s with the appropriate transmittance characteristics can prevent blue-light exposure limits from being exceeded by dental healthcare professionals. The objective of this study was to investigate the development of a standard test method to evaluate the suitability of a PFD for a given LCU by using blue-light weighted (BLW) transmittance of the PFD and BLW radiance of the LCU.
Methods: The spectral power outputs of 2 LCUs (Table1) were recorded 20 cm from a Labsphere integrating sphere (with a 7 mm aperture) attached to a Flame, Ocean Optics spectrometer (Figure1A). Blue-light weighted (BLW) radiance values were calculated for each LCU at each power setting using Figure1A equations. Spectral transmittance of 3 PFDs (Table1) were also measured using the integrating-sphere/spectrometer assembly with a broadband light source and collimating lens (Figure1B). BLW transmittance values were calculated using ISO 12609-1 equations (Figure1B). The BLW radiance exposure limit (BLWREL), as specified in IEC 62471 for the lowest risk group category, is 100 W/m2/sr. A corresponding maximum BLW filter transmittance limit was calculated by dividing the BLWREL by each BLW radiance value for each LCU. Use of the PFD with BLW transmittance greater than this maximum limit may be considered inappropriate for preventing retinal damage from the given LCU.
Results: The maximum BLW transmittance limit for each LCU power setting varied from 1.08% to 4.57%, and the BLW transmittance for 3 PFDs varied from 0.10% for Infield to 1.71% for Vinmax, which exceeded the BLW transmittance limit for the Elipar LCU (Table1).
Conclusions: This study demonstrated a method for combining measurements of BLW transmittance values of PFDs with measurements of BLW radiance values for dental LCUs to establish maximum BLW transmittance limits. This method may be suitable as a standard method to set BLW transmittance requirements for PFDs used with specified dental LCUs.
Methods: The spectral power outputs of 2 LCUs (Table1) were recorded 20 cm from a Labsphere integrating sphere (with a 7 mm aperture) attached to a Flame, Ocean Optics spectrometer (Figure1A). Blue-light weighted (BLW) radiance values were calculated for each LCU at each power setting using Figure1A equations. Spectral transmittance of 3 PFDs (Table1) were also measured using the integrating-sphere/spectrometer assembly with a broadband light source and collimating lens (Figure1B). BLW transmittance values were calculated using ISO 12609-1 equations (Figure1B). The BLW radiance exposure limit (BLWREL), as specified in IEC 62471 for the lowest risk group category, is 100 W/m2/sr. A corresponding maximum BLW filter transmittance limit was calculated by dividing the BLWREL by each BLW radiance value for each LCU. Use of the PFD with BLW transmittance greater than this maximum limit may be considered inappropriate for preventing retinal damage from the given LCU.
Results: The maximum BLW transmittance limit for each LCU power setting varied from 1.08% to 4.57%, and the BLW transmittance for 3 PFDs varied from 0.10% for Infield to 1.71% for Vinmax, which exceeded the BLW transmittance limit for the Elipar LCU (Table1).
Conclusions: This study demonstrated a method for combining measurements of BLW transmittance values of PFDs with measurements of BLW radiance values for dental LCUs to establish maximum BLW transmittance limits. This method may be suitable as a standard method to set BLW transmittance requirements for PFDs used with specified dental LCUs.
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