title: Influence of extended light exposure time on the degree of conversion and plasticization of materials used as pit and fissure sealants.
abstract: OBJECTIVE
  To evaluate the conversion and plasticization of fissure sealer materials, as influenced by extended curing time.
  
  
  METHODS
  Twenty specimens (n=5) of a pit and fissure sealant and a flowable composite at two curing times (20 and 60 sec) were photocured with the Bluephase 16i light-emitting diode. The conversion was determined by Fourier transform infrared/attenuated total reflection spectroscopy 24 h after polymerization. Hardness was measured, and samples were stored in absolute ethanol for 24 h. A second hardness measurement was executed after storage to assess plasticization by the percentage of hardness decrease. Data were analyzed by analysis of variance and Pearson's correlation (α=0.05).
  
  
  RESULTS
  The pit and fissure sealant showed lower degree of conversion than the flowable composite. The 60-sec curing time increased the conversion only for the flowable composite. Plasticization was lower for the flowable composite than for the pit and fissure sealant. The 60-sec light exposure time showed a similar percentage of hardness decrease of 20 sec. A low correlation between the conversion and plasticization was found.
  
  
  CONCLUSIONS
  Extended curing time improved the conversion only for the flowable composite. The pit and fissure sealant presented lower conversion and higher plasticization than the flowable composite.
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Piracicaba, Brazil. boniek.castillo@gmail.com
authors.forename: Boniek Castillo Dutra
authors.initials: BC
authors.lastname: Borges
authors.forename: Eduardo José
authors.initials: EJ
authors.lastname: Souza-Júnior
authors.forename: Anderson
authors.initials: A
authors.lastname: Catelan
authors.forename: José Roberto
authors.initials: JR
authors.lastname: Lovadino
authors.forename: Paulo Henrique
authors.initials: PH
authors.lastname: Dos Santos
authors.forename: Luís Alexandre Maffei Sartini
authors.initials: LA
authors.lastname: Paulillo
authors.forename: Flávio Henrique Baggio
authors.initials: FH
authors.lastname: Aguiar
mesh_terms: D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D055117:Curing Lights, Dental / Q000145:classification; D003764:Dental Materials / Q000737:chemistry; D000431:Ethanol / Q000737:chemistry; D006244:Hardness; D006801:Humans; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D008422:Materials Testing; D010895:Pit and Fissure Sealants / Q000737:chemistry*; D010968:Plasticizers / Q000737:chemistry; D058105:Polymerization; D011140:Polyurethanes / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013057:Spectrum Analysis; D013499:Surface Properties; D013997:Time Factors
chemical_list: D003188:Composite Resins; D003764:Dental Materials; C423507:PermaFlow; D010895:Pit and Fissure Sealants; D010968:Plasticizers; D011140:Polyurethanes; D012997:Solvents; C111840:flowable hybrid composite; C086661:Fluoroshield; D000431:Ethanol; D017438:Bisphenol A-Glycidyl Methacrylate
keywords: flowable composite; hardness test; in vitro; light-emitting diode; pit and fissure sealant