title: Effect of self and dual-curing on degree of conversion and crosslink density of dual-cure core build-up materials.
abstract: OBJECTIVE
  Dual-cure core build-up resins have been developed to take advantages of both self and light-cured resin. The aim of present study was to determine the polymerization characteristics of self and dual-cured modes of dual-cure core build-up composites evaluating degree of conversion (DC) and crosslink density by measurement of glass-transition temperature (Tg) and hardness decrease in ethanol.
  
  
  METHODS
  Clearfil Dc Core Automix (CLF) and Grandio Core Dc (GR) core build-up resins were selected. Twelve specimens for both composites were polymerized using quartz-halogen-tungsten light curing unit (QTH) and 12 specimens polymerized chemically. DC was determined by ATR-FTIR spectroscopy. TG/DTA analysis was performed to determine Tg. Microhardness value of specimens was determined by Vickers-tester before and after specimens stored in absolute ethanol for 24h.
  
  
  RESULTS
  One-way ANOVA showed no different DC values between dual and self-cured mode of GR and dual-cured CLF composites had higher DC than self-cured mode. Tg and percentage of softening in ethanol values of GR and CLF revealed significant difference between self and dual-cured mode.
  
  
  CONCLUSIONS
  In comparison of GR and CLF, DC showed no statistical difference in both curing modes. However, dual and self-cured GR has statistically higher Tg values and lower percentage of softening in ethanol than CLF. Polymerization characteristics of dual-cure core build-up composites have superiority in dual-cured mode than self-cured.
authors.affiliation: Department of Prosthodontics, Faculty of Dentistry, University of Gazi, Ankara, Turkey. Electronic address: dtduygukc@hotmail.com.
authors.forename: Duygu
authors.initials: D
authors.lastname: Karakis
authors.affiliation: Department of Prosthodontics, Faculty of Dentistry, University of Gazi, Ankara, Turkey.
authors.forename: Arzu Zeynep
authors.initials: AZ
authors.lastname: Yıldırım-Bicer
authors.affiliation: Department of Prosthodontics, Faculty of Dentistry, University of Gazi, Ankara, Turkey.
authors.forename: Arife
authors.initials: A
authors.lastname: Dogan
authors.affiliation: Department of Physics, Faculty of Science, University of Gazi, Ankara, Turkey.
authors.forename: Haluk
authors.initials: H
authors.lastname: Koralay
authors.affiliation: Department of Physics, Faculty of Science, University of Gazi, Ankara, Turkey.
authors.forename: Sukru
authors.initials: S
authors.lastname: Cavdar
mesh_terms: D000180:Acrylic Resins; D055598:Chemical Phenomena; D003188:Composite Resins; D000431:Ethanol; D006244:Hardness; D055115:Light-Curing of Dental Adhesives; D058105:Polymerization; D011140:Polyurethanes; D044366:Transition Temperature
chemical_list: D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D011140:Polyurethanes; D000431:Ethanol
keywords: Crosslink density; Degree of conversion; Dual cure resin; Glass transition temperature; Hardness; Self curing