title: Comparison of the heat generation of light curing units.
abstract: OBJECTIVE
  The aim of this study was to evaluate the heat generation of three different types of light curing units.
  
  
  METHODS
  Temperature increases were recorded from a distance of 1 mm from a thermocouple to the tip of three different types of light curing units including one quartz-tungsten halogen (QTH), one plasma arc (PAC), and one light emitting diode (LED) unit. An experimental model was designed to fix the 1 mm distance between the tip of the light curing units and the thermocouple wire. Temperature changes were recorded in 10 second intervals up to 40 seconds. (10, 20, 30, and 40 seconds). Temperature measurements were repeated three times for every light curing unit after a one hour standby period. Statistical analysis of the results was performed using the analysis of variance (ANOVA) and the Bonferroni Test.
  
  
  RESULTS
  The highest temperature rises (54.4+/-1.65 degrees C) occurred during activation of a PAC light curing unit for every test period (p<.05). The least temperature increase (11.8+/-1.3 degrees C) occurred with a LED curing unit for each tested period except for the measurement of the temperature rise using the QTH curing unit at the tenth second interval (p<.05).
  
  
  CONCLUSIONS
  These results indicate the choice of light activation unit and curing time is important when polymerizing light activated resin based restorations to avoid any thermal damage to the pulp.
authors.affiliation: Department of Prosthetic Dentistry of the Faculty of Dentistry at Karadeniz Technical University in Trabzon, Turkey. bbagis@yahoo.com
authors.forename: Bora
authors.initials: B
authors.lastname: Bagis
authors.forename: Yildirim
authors.initials: Y
authors.lastname: Bagis
authors.forename: Ertan
authors.initials: E
authors.lastname: Ertas
authors.forename: Seda
authors.initials: S
authors.lastname: Ustaomer
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000528:radiation effects*; D003748:Dental Equipment; D006219:Halogens; D006358:Hot Temperature; D008027:Light; D044367:Phase Transition; D012666:Semiconductors; D018709:Statistics, Nonparametric; D013997:Time Factors; D014978:Xenon
chemical_list: D003188:Composite Resins; D006219:Halogens; D014978:Xenon