title: Effect of LED and Argon Laser on Degree of Conversion and Temperature Rise of Hybrid and Low Shrinkage Composite Resins.
abstract: OBJECTIVE
  Different light curing units are used for polymerization of composite resins. The aim of this study was to evaluate the degree of conversion (DC) and temperature rise in hybrid and low shrinkage composite resins cured by LED and Argon Laser curing lights.
  
  
  METHODS
  DC was measured using FTIR spectroscopy. For measuring temperature rise, composite resin samples were placed in Teflon molds and cured from the top. The thermocouple under samples recorded the temperature rise. After initial radiation and specimens reaching the ambient temperature, reirradiation was done and temperature was recorded again. Both temperature rise and DC data submitted to one-way ANOVA and Tukey-HSD tests (5% significance).
  
  
  RESULTS
  The obtained results revealed that DC was not significantly different between the understudy composite resins or curing units. Low shrinkage composite resin showed a significantly higher temperature rise than hybrid composite resin. Argon laser caused the lowest temperature rise among the curing units.
  
  
  CONCLUSIONS
  Energy density of light curing units was correlated with the DC. Type of composite resin and light curing unit had a significant effect on temperature rise due to polymerization and curing unit, respectively.
authors.affiliation: Operative Dentist, Tehran University of Medical Science, North Amir-Abad, Tehran, Iran.
authors.forename: Ayob
authors.initials: A
authors.lastname: Pahlevan
authors.affiliation: Operative Dentist, Tehran University of Medical Science, North Amir-Abad, Tehran, Iran.
authors.forename: Masumeh Hasani
authors.initials: MH
authors.lastname: Tabatabaei
authors.affiliation: Operative Dentist, Tehran University of Medical Science, North Amir-Abad, Tehran, Iran.
authors.forename: Sakineh
authors.initials: S
authors.lastname: Arami
authors.affiliation: Operative Dentist, Tehran University of Medical Science, North Amir-Abad, Tehran, Iran.
authors.forename: Sara
authors.initials: S
authors.lastname: Valizadeh
keywords: Argon laser; DC; LED; Low shrinkage composite; Temperature rise