Intra- and inter-brand accuracy of four dental radiometers.

This study measured the accuracy and precision of four commercial dental radiometers. The intra-brand accuracy was also determined. The light outputs from 14 different curing lights were measured three times using four brands of dental radiometers and the results were compared to two laboratory-grade power meters that were used as the "gold standard". To ensure proper representation, three examples of each brand of dental radiometer were used. Data collected was analyzed using ANOVA, with 95% confidence intervals, comparing the laboratory-grade meters to the dental radiometers. Bioequivalence was established where the confidence interval for the irradiance values was within ±20% of the "gold standard" reading. Forest plots were used to highlight bioequivalence values. The two laboratory-grade meters differed by less than 0.6%. Overall, all three examples of the Bluephase and SDI radiometers as well as two examples of the LEDRadiometer and one CureRite meter were bioequivalent to the gold standard. However, the type of curing light measured had a significant effect on the accuracy of the radiometer. There was significant variability of the irradiance readings between radiometer brands, and between irradiance values recorded by the three samples of each brand studied. This made it impossible to definitively rank the radiometer brands for accuracy. Within the ±20% bioequivalence limits of this study, there was a clinically significant difference in the irradiance readings between radiometer brands and the choice of curing light affected the results. There was also significant variation in irradiance readings reported by different examples of the same brand of radiometer. Whether in clinical practice or in research, dental radiometers should not be used when either the irradiance or energy delivered needs to be accurately known.