title: Evaluation of microleakage of class II dental composite resin restorations cured with LED or QTH dental curing light; Blind, Cluster Randomized, In vitro cross sectional study.
abstract: BACKGROUND
  The aim of this study is to compare the microleakage of Class II dental composite resin restorations which have been cured by three different LED (light emitting diode) light curing modes compared to control samples cured by QTH (quartz tungsten halogen) light curing units (LCUs), to determine the most effective light curing unit and mode of curing.
  
  
  RESULTS
  In this experimental study, class II cavities were prepared on 100 sound human premolars which have been extracted for orthodontic treatment. The teeth were randomly divided into four groups; three experimental and one control group of 25 teeth each. Experimental groups were cured by either conventional, pulse-delay, or ramped curing modes of LED. The control group was cured for 20 seconds by QTH. The restorations were thermocycled (1000 times, between 5 and 55°C, for 5 seconds dwell time), dyed, sectioned mesio-distally and viewed under stereo-microscope (40×) magnification. Teeth were then scored on a 0 to 4 scale based on the amount of microleakage. The data were analyzed by Chi-square test.No significant difference was demonstrated between the different LCUs (light curing units), or modes of curing, at the enamel side (p > 0.05). At the dentin side, all modes of LED curing could significantly reduce microleakage (p < 0.05). The results suggest that slow start curing improves marginal integrity and seal. High intense curing endangers those aims.
  
  
  CONCLUSIONS
  Comparison between the three LED mode cured composite resin restorations and QTH curing showed LED curing in all modes is more effective than QTH for reducing microleakage. Both LED and QTH almost completely eliminate the microleakage on the enamel side, however none of them absolutely eliminated microleakage on the dentin side.
authors.forename: Faramarz
authors.initials: F
authors.lastname: Zakavi
authors.forename: Leila
authors.initials: L
authors.lastname: Golpasand Hagh
authors.forename: Soheila
authors.initials: S
authors.lastname: Sadeghian
authors.forename: Virginia
authors.initials: V
authors.lastname: Freckelton
authors.affiliation: Department of Operative and Esthetic Dentistry, Ahvaz Jundishapur Dental School, Ahvaz Jundishapur University of Medical Sciences, Ahvaz 6135715775, Iran. adaraei@pacific.edu.
authors.forename: Arash
authors.initials: A
authors.lastname: Daraeighadikolaei
authors.forename: Elham
authors.initials: E
authors.lastname: Ghanatir
authors.forename: Najmeh
authors.initials: N
authors.lastname: Zarnaghash
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry / Q000528:radiation effects*; D001641:Bicuspid / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects*; D003430:Cross-Sectional Studies; D055117:Curing Lights, Dental; D003763:Dental Leakage; D003793:Dental Restoration, Permanent; D006801:Humans; D011140:Polyurethanes / Q000737:chemistry / Q000528:radiation effects*; D014081:Tooth Extraction
chemical_list: D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D011140:Polyurethanes