title: Accuracy of LED and halogen radiometers using different light sources.
abstract: OBJECTIVE
  To determine the accuracy of commercially available, handheld light-emitting diode (LED) and halogen-based radiometers using LED and quartz-tungsten-halogen (QTH) curing lights with light guides of various diameters.
  
  
  METHODS
  The irradiance of an LED curing light (L.E. Demetron 1, SDS/Kerr, Orange, CA, USA) and a QTH curing light (Optilux 501, SDS/Kerr) were measured using multiple units of an LED (Demetron L.E.D. Radiometer, SDS/Kerr) and a halogen radiometer (Demetron 100, SDS/Kerr) and compared with each other and to a laboratory-grade power meter (control). Measurements were made using five light guides with distal light guide diameters of 4, 7, 8, 10, and 12.5 mm. For each light guide, five readings were made with each of three radiometers of each radiometer type. Data were analyzed with two-way analysis of variance/Tukey; alpha = 0.05.
  
  
  RESULTS
  In general, both handheld radiometer types exhibited significantly different irradiance readings compared with the control meter. Additionally, readings between radiometer types were found to differ slightly, but were correlated. In general, the LED radiometer provided slightly lower irradiance readings than the halogen radiometer, irrespective of light source. With both types of handheld radiometers, the use of the larger-diameter light guides tended to overestimate the irradiance values as seen in the control, while smaller-diameter light guides tended to underestimate.
  
  
  CONCLUSIONS
  The evaluated LED or halogen handheld radiometers may be used interchangeably to determine the irradiance of both LED and QTH visible-light-curing units. Measured differences between the two radiometer types were small and probably not clinically significant. However, the diameter of light guides may affect the accuracy of the radiometers, with larger-diameter light guides overestimating and smaller-diameter guides underestimating the irradiance value measured by the control instrument.
authors.affiliation: Graduate Dental Biomaterials, Marquette University, Milwaukee, WI, USA. hwroberts@nidbr.med.navy.mil
authors.forename: Howard W
authors.initials: HW
authors.lastname: Roberts
authors.forename: Kraig S
authors.initials: KS
authors.lastname: Vandewalle
authors.forename: David W
authors.initials: DW
authors.lastname: Berzins
authors.forename: David G
authors.initials: DG
authors.lastname: Charlton
mesh_terms: D000704:Analysis of Variance; D003748:Dental Equipment; D006219:Halogens; D008027:Light; D044367:Phase Transition; D011874:Radiometry / Q000295:instrumentation*; D012044:Regression Analysis; D012666:Semiconductors
chemical_list: D006219:Halogens