title: Comparative evaluation of the microhardness of 4 dental sealants.
abstract: OBJECTIVE
  Aim of this study was the evaluation of the microhardness of 4 dental sealants polymerised with two different curing units.
  
  
  METHODS
  Twenty samples (5 x 5x 2 mm) were prepared with 4 different sealants; 10 samples for each group were polymerised with a plasma curing unit (Apollo 95 E DMD) and 10 with a halogen curing light (Heliolux DLX Vivadent ETS, Schaan, Liechtenstein). For each section 6 Vickers microhardness measurements were performed (VMHT 30A, Leica Wien, Austria), 3 on the surface exposed to the light and 3 on the opposite surface. After the baseline assessment all samples were stored in artificial saliva at 37 degrees C for 30, 60, 90, 180 and 360 days, and then analysed again with the microhardness indenter and observed under steromicroscope 10X (Leica DM2500 Wien, Austria). Data were then statistically analysed.
  
  
  RESULTS
  The hybrid composite Tetric flow (group IV) showed the higher microhardness values compared to the other tested materials (group I, II, III); surfaces exposed to curing light showed higher microhardness values than opposite surfaces. Moreover, a significant microhardness reduction was observed after 30 days; values remained unmodified after 60, 90, 180 and 360 days.
  
  
  METHODS
  Data were then statistically analysed with Anova test for repeated measures, with a global significance level of 0.05.
  
  
  CONCLUSIONS
  Because of the good mechanical properties of dental sealants they represent the first choice materials in pits and fissures sealing.
authors.affiliation: Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Trieste, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Bevilacqua
authors.forename: A
authors.initials: A
authors.lastname: Sossi
authors.forename: M
authors.initials: M
authors.lastname: Cadenaro
authors.forename: R
authors.initials: R
authors.lastname: Di Lenarda
mesh_terms: D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry / Q000528:radiation effects; D020770:Compomers / Q000737:chemistry / Q000528:radiation effects; D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D003799:Dental Stress Analysis; D006245:Hardness Tests; D008027:Light; D008422:Materials Testing; D010895:Pit and Fissure Sealants / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D020770:Compomers; D003188:Composite Resins; D010895:Pit and Fissure Sealants; C496147:dyract seal; C452226:tetric flow composite resin; C059908:Helioseal; D017438:Bisphenol A-Glycidyl Methacrylate