Accuracy of Irradiance and Power of Light-Curing Units Measured With Handheld or Laboratory Grade Radiometers

Abstract

This study measured and compared exitance irradiance and power of 4 commercial dental light-curing units (LCU) (Elipar S10, Elipar DeepCure-S, Corded VALO and Bluephase Style) using different types of radiometers. The devices used to analyze the LCU were classified as either handheld analog (Henry Schein, Spring, Demetron 100A, Demetron 100B and Demetron 200), handheld digital (Bluephase 1, Bluephase II, Coltolux, CureRite and Hilux), or laboratory instruments (Thermopile and Integrating Sphere). The laboratory instruments and the Bluephase II radiometer were also used to measure the LCU’s power (mW). The LCU’s were activated for 20 s (n=5). Data were analyzed using Kruskal-Wallis and Student-Newman-Keuls multiple comparison test (a=0.05). Among the LCU, the laboratory instruments presented different irradiance values, except for Corded VALO. The Coltolux and Hilux radiometers measured greater irradiance values compared to the laboratory instruments for the four LCUs tested. Within a given LCU, handheld analog units measured lower irradiance values, compared to handheld digital and laboratory instruments, except using the Spring radiometer for the Elipar S10 LCU. None of the handheld radiometers were able to measure similar irradiance values compared to laboratory instruments, except for Elipar S10 when comparing Bluephase 1 and Thermopile. Regarding power measurement, Bluephase II always presented the lowest values compared to the laboratory instruments. These findings suggest that the handheld radiometers utilized by practitioners (analog or digital) exhibit a wide range of irradiance values and may show lower outcomes compared to laboratory based instruments.

Irradiance from 12 LED light curing units measured using 5 brands of dental radiometers

“…because the Bluephase Meter II only accepts whole numbers when entering the diameter of the light tip. 54 For example, if the power output is 1,000 mW and the tip diameter is 9.5 mm, then the calculated irradiance would be 1,411 mW/cm 2 . However, because the Bluephase Meter II only accepts whole numbers if a tip diameter of 9 mm was used, the meter would report an irradiance of 1,572 mW/cm 2 .…”

“…Further study is required to determine the effect of use on these LCUs and radiometers. Some errors will have been introduced because the Bluephase Meter II only accepts whole numbers when entering the diameter of the light tip 54 . For example, if the power output is 1,000 mW and the tip diameter is 9.5 mm, then the calculated irradiance would be 1,411 mW/cm 2 .…”

“…This will alert the clinician to any problems with the LCU. They can then determine if the LCU is degrading, if the light guide or tip lens is contaminated, or if the batteries or the LCU itself needs to be replaced 45,54 …”

The light-curing unit: An essential piece of dental equipment

“…Then, depending on the percent decrease in the radiant exitance caused by the barrier, the clinician should increase the exposure times that they would use in the mouth 81À84 . The Bluephase Meter II has been shown to be an accurate (AE 10%) dental radiometer that can measure the radiant power and, when the tip diameter is entered, this meter device can also report the radiant exitance 85,86 . As an added benefit, when the dentist measures the output from their LCU, they quickly realise the effects of battery discharge 38À41,43 , the barrier they use 81À84 , and both tip angulation and distance 23,44À46,60 have on the light received.…”