title: Optical power outputs, spectra and dental composite depths of cure, obtained with blue light emitting diode (LED) and halogen light curing units (LCUs).
abstract: OBJECTIVE
  To test the hypothesis that a prototype LED light curing unit, (LCU), a commercial LED LCU and a halogen LCU achieve similar cure depths, using two shades of a camphorquinone photoinitiated dental composite. To measure the LCUs' outputs and the frequency of the LED LCU's pulsed light, using a blue LED array as a photodetector.
  
  
  METHODS
  Cure depth and light output characterisation to compare the LCUs.
  
  
  METHODS
  An in vitro laboratory study conducted in the UK.
  
  
  METHODS
  The LCUs cured A2 and A4 composite shades. A penetrometer measured the depth of cure. Analysis was by one-way ANOVA, two-way univariate ANOVA and Fisher's LSD test with a 95% confidence interval. A power meter and spectrograph characterised the LCUs' emissions. A blue LED array measured the pulsed light frequency from an LED LCU.
  
  
  RESULTS
  Statistically significant different LCU irradiances (119 mW/cm2 to 851 mW/cm2) and cure depths (3.90 mm SD +/- 0.08 to 6.68 mm SD +/- 0.07) were achieved. Composite shade affected cure depth. A blue LED array detected pulsed light at 12 Hz from the commercial LED LCU.
  
  
  CONCLUSIONS
  The prototype LED LCU achieved a greater or equal depth of cure when compared with the commercial LCUs. LEDs may have a potential in dentistry for light detection as well as emission.
authors.affiliation: University of Bristol, Dental School, Department of Oral and Dental Science, Biomedical Engineering and Biomaterials Science Section.
authors.forename: R W
authors.initials: RW
authors.lastname: Mills
authors.forename: A
authors.initials: A
authors.lastname: Uhl
authors.forename: K D
authors.initials: KD
authors.lastname: Jandt
mesh_terms: D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects*; D003748:Dental Equipment; D006219:Halogens; D008027:Light; D008422:Materials Testing; D012666:Semiconductors; D013674:Technology, Dental / Q000295:instrumentation*
chemical_list: D003188:Composite Resins; D006219:Halogens