title: The effects of halogen and light-emitting diode light curing on the depth of cure and surface microhardness of composite resins.
abstract: OBJECTIVE
  Light-emitting diode light curing units (LED LCUs) have become more popular than halogen LCUs in routine dental restorative treatment. The aim of the study was to compare the effects of two conventional halogen (Hilux Plus and VIP) and two LED (Elipar FreeLight 2 and Smart Lite) light curing units on the depth of cure and the microhardness of various esthetic restorative materials.
  
  
  METHODS
  The curing depth and microhardness of a compomer (Dyract Extra), a resin-modified glass ionomer (Vitremer), a packable composite (Sculpt It), an ormocer (Admira), a hybrid composite (Tetric Ceram), two microhybrid composites (Miris and Clearfil Photo Posterior) and, a nanofil composite (Filtek Supreme) were determined using a scraping method and a hardness tester. A total of 320 samples were prepared using the eight different materials (n = 10 samples for each subgroup). The scraping test was based on ISO 4049:2000. Vicker's microhardness testing was carried out using hardness tester (Zwick 3212). Data were analyzed using one-way analysis of variance (ANOVA), Bonferroni and the Kolmogorov-Smirnov tests.
  
  
  RESULTS
  Best microhardness results were obtained with the LED light curing units and Tetric EvoCeram and Filtek Supreme achieved the highest hardness values. The nanofil composite, Filtek Supreme, showed the best curing depth results in all the tested light curing systems.
  
  
  CONCLUSIONS
  The LEDs were found to be more successful than the halogen units with respect to both curing depth and microhardness properties.
authors.affiliation: Department of Operative Dentistry, Faculty of Dentistry, Istanbul University, Capa/Fatih-34093, Istanbul, Turkey.
authors.forename: Batu Can
authors.initials: BC
authors.lastname: Yaman
authors.forename: Begüm Güray
authors.initials: BG
authors.lastname: Efes
authors.forename: Can
authors.initials: C
authors.lastname: Dörter
authors.forename: Yavuz
authors.initials: Y
authors.lastname: Gömeç
authors.forename: Dina
authors.initials: D
authors.lastname: Erdilek
authors.forename: Sami
authors.initials: S
authors.lastname: Büyükgökçesu