title: Effects of exposure time and exposure distance on the degree of cure in light-activated pit and fissure sealants.
abstract: OBJECTIVE
  The study aims to measure and compare the effect of different exposure times and exposure distances on the degree of cure (DC) of light hardening resin based pit and fissure sealants.
  
  
  METHODS
  A representative selection of 13 commercial sealants brands was chosen. DC of each material (n=6) was measured in real-time by Fourier transform infrared spectroscopy (FTIR) at three clinically relevant exposure times (10, 20, 40s) and two fixed exposure distances (4mm and 7 mm) between sample and light source. Data were analyzed by a multi-variant analysis and partial eta-squared statistic.
  
  
  RESULTS
  Factors "material", "exposure time" and "exposure distance" had a significant influence on the DC across all materials (ηp(2)=0.927,0.774 and 0.266 respectively) with "material" and "exposure time" showing the strongest effect (significance level α ≤ 0.05). In general, an increased exposure time and reduced exposure distance between sample and light source led to increased DC for all the materials.
  
  
  CONCLUSIONS
  Degree of cure is influenced significantly by the brand of sealant and by exposure time. In some cases it is found that DC is also affected significantly by the exposure distance.
  
  
  CONCLUSIONS
  On the basis of this study, an exposure time of at least 20s and a maximum exposure distance of 4mm between curing unit and material surface is recommended.
authors.affiliation: Department of Restorative Dentistry, Dental School of Ludwig-Maximilians-University, Goethestr. 70, 80336 Munich, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Holroyd
authors.forename: Nicoleta
authors.initials: N
authors.lastname: Ilie
mesh_terms: D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D020770:Compomers / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D055117:Curing Lights, Dental; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D055115:Light-Curing of Dental Adhesives / Q000295:instrumentation / Q000379:methods*; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D010895:Pit and Fissure Sealants / Q000737:chemistry*; D058105:Polymerization; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013997:Time Factors
chemical_list: C500418:Clinpro Sealant; D020770:Compomers; D003188:Composite Resins; C586521:Embrace WetBond; C407603:Fissurit F; D005899:Glass Ionomer Cements; C509998:Grandio; C091836:Ionosit; D008689:Methacrylates; D010895:Pit and Fissure Sealants; C106663:Ultra Seal XT; C496147:dyract seal; C099291:teethmate-FTM; C059908:Helioseal; D017438:Bisphenol A-Glycidyl Methacrylate
keywords: Degree of cure; Exposure distance; Exposure time; Pit and fissure sealants