title: Effect of different polymerization methods on the cytotoxicity of dental composites.
abstract: OBJECTIVE
  The aim of this study was to compare the cytotoxic effects of various dental composites polymerized with two different curing units.
  
  
  METHODS
  Disc-shaped test samples of composites Filtek Z250, Filtek A110, Filtek P60, Filtek Supreme, and SDI Rok were polymerized using one quartz tungsten halogen (QTH) and one light emitting diode (LED) light curing unit (LCU), namely Optilux 501 (QTH) and Elipar Freelight 2 (LED). L-929 mouse fibroblast cultures (3x10(4) cells/ml) were incubated with the samples in 96 well culture plates for evaluation after 8, 24, 48, 72 h. At the end of each period, the cells were counted and examined under a light microscope, and a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay was performed. The degree of cytotoxicity for each sample was determined according to the reference value represented by the cells in a control group (a culture without sample).
  
  
  RESULTS
  A significant 3 factor interaction occurred among LCUs, composites, and time factors (P<.005). In general, the test materials cured with the LED LCU demonstrated higher cell survival rates when compared with those cured with halogen LCUs.
  
  
  CONCLUSIONS
  This study shows that polymerization of dental composites with a light emitting diode LCU positively influences the L-929 mouse fibroblast cell viability.
authors.affiliation: Hacettepe University, School of Dental Technology, Ankara, Turkey.
authors.forename: Nilufer Celebi
authors.initials: NC
authors.lastname: Beriat
authors.forename: Ahmet Atila
authors.initials: AA
authors.lastname: Ertan
authors.forename: Senay
authors.initials: S
authors.lastname: Canay
authors.forename: Aylin
authors.initials: A
authors.lastname: Gurpinar
authors.forename: Mehmet Ali
authors.initials: MA
authors.lastname: Onur