title: Influence of heat from light curing units and dental composite polymerization on cells in vitro.
abstract: OBJECTIVE
  The aim of the present study was to test the hypothesis that the use of a light curing unit (LCU) with high light power would result in a higher temperature and therefore a statistically significant lower number of living human gingiva fibroblasts within a pulp chamber model than the use of a light emitting diode (LED) LCU.
  
  
  METHODS
  The composites Admira, Grandio, Filtek Supreme and Filtek Z250 were polymerized with the LCUs Swiss Master Light, Optilux 501 and an LED LCU prototype in a mould on top of a pulp chamber model. The temperature was recorded within the pulp chamber with a thermocouple. The cytotoxicity of the polymerized samples was tested by using the MTT test.
  
  
  RESULTS
  In general there was no considerable difference in the temperature increase within the pulp chamber model for the different LCUs and composites. There was no statistically significant difference in the cell number (p=0.3767) when the different LCUs were used.
  
  
  CONCLUSIONS
  Using a high power halogen LCU for a short time or a standard halogen or LED LCU for a longer time did not result in a considerable difference in the temperature increase or the number of living cells within a pulp chamber model. This study indicates not only that the temperature may have an effect on the living cells, but also that cells may be negatively affected by the unpolymerized composite or light of the LCUs.
authors.affiliation: Electro Medical Systems (EMS) SA, Chemin de la Vuarpillière 31, CH-1260 Nyon, Switzerland, and Department of Conservative Dentistry, Friedrich-Schiller-University Jena, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Uhl
authors.forename: Andrea
authors.initials: A
authors.lastname: Völpel
authors.forename: Bernd W
authors.initials: BW
authors.lastname: Sigusch
mesh_terms: D000180:Acrylic Resins / Q000009:adverse effects / Q000528:radiation effects*; D000704:Analysis of Variance; D003188:Composite Resins / Q000009:adverse effects / Q000528:radiation effects*; D003786:Dental Pulp Cavity / Q000166:cytology / Q000528:radiation effects*; D005347:Fibroblasts / Q000528:radiation effects*; D005881:Gingiva / Q000166:cytology / Q000528:radiation effects*; D006219:Halogens / Q000009:adverse effects; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D011140:Polyurethanes / Q000009:adverse effects / Q000528:radiation effects*
chemical_list: D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D006219:Halogens; D011140:Polyurethanes