title: Dental composite depth of cure with halogen and blue light emitting diode technology.
abstract: OBJECTIVE
  To test the hypothesis that a blue light emitting diode (LED) light curing unit (LCU) can produce an equal dental composite depth of cure to a halogen LCU adjusted to give an irradiance of 300 mWcm-2 and to characterise the LCU's light outputs.
  
  
  METHODS
  Depth of cure for three popular composites was determined using a penetrometer. The Student's t test was used to analyse the depth of cure results. A power meter and a spectrometer measured the light output.
  
  
  RESULTS
  The spectral distribution of the LCUs differed strongly. The irradiance for the LED and halogen LCUs were 290 mWcm-2 and 455 mWcm-2, when calculated from the scientific power meter measurements. The LED LCU cured all three dental composites to a significantly greater (P < 0.05) depth than the halogen LCU.
  
  
  CONCLUSIONS
  An LED LCU with an irradiance 64% of a halogen LCU achieved a significantly greater depth of cure. The LCU's spectral distribution of emitted light should be considered in addition to irradiance as a performance indicator. LED LCUs may have a potential for use in dental practice because their performance does not significantly reduce with time as do conventional halogen LCUs.
authors.affiliation: Department of Oral and Dental Science, University of Bristol.
authors.forename: R W
authors.initials: RW
authors.lastname: Mills
authors.forename: K D
authors.initials: KD
authors.lastname: Jandt
authors.forename: S H
authors.initials: SH
authors.lastname: Ashworth
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D003748:Dental Equipment; D006219:Halogens; D008027:Light; D011874:Radiometry; D012666:Semiconductors
chemical_list: D003188:Composite Resins; D006219:Halogens