title: Marginal adaptation of composite restorations photoactivated by LED, plasma arc, and QTH light using low-modulus resin liners.
abstract: OBJECTIVE
  The aim of this study was to evaluate the influence of resin liners on the marginal adaptation to dentin of resin composite restorations photoactivated by a conventional quartz-tungsten halogen lamp (QTH), light emitting diodes (LED), and a plasma arc light (PAC).
  
  
  METHODS
  The buccal surfaces of 120 bovine incisors were ground until a flat dentin area was obtained. A circular cavity (4 mm in diameter x 1.5 mm in depth) was prepared in this area. Scotchbond Multi Purpose was applied in the cavities following the manufacturer's instructions. The specimens were randomly assigned into 4 groups according to the lining technique: (1) control (1 adhesive layer); (2) three adhesive layers; (3) Filtek Flow; (4) Protect Liner F. Each group was further divided into 3 subgroups according to the light-curing method: (A) QTH; (B) LED; (C) PAC. All cavities were then restored with a single increment of Filtek Z250 restorative composite and polished. Caries Detector was applied to each specimen for 5 s. Images of dye-stained gaps were observed under a stereomicroscope and transferred to a computer measurement program. Gap values were obtained by dividing the dyed margin length by the total cavity length, then multiplying by 100. Data were analyzed using ANOVA and Tukey's test (p < 0.05).
  
  
  RESULTS
  All the tested lining techniques significantly decreased marginal gap formation when compared with the control group only for the QTH light groups. There was no significant difference among the light-curing methods.
  
  
  CONCLUSIONS
  The use of resin liners can effectively reduce the gap formation along dentin margins, but only when QTH light is used.
authors.affiliation: Department of Restorative Dentistry, Dental Materials Area, Piracicaba Dental School, UNICAMP, Piracicaba, São Paulo, Brazil. robalonso@fop.unicamp.br
authors.forename: Roberta Caroline Bruschi
authors.initials: RC
authors.lastname: Alonso
authors.forename: Leonardo Gonçalves
authors.initials: LG
authors.lastname: Cunha
authors.forename: Gisele Maria
authors.initials: GM
authors.lastname: Correr
authors.forename: Regina Maria
authors.initials: RM
authors.lastname: Puppin-Rontani
authors.forename: Lourenço
authors.initials: L
authors.lastname: Correr-Sobrinho
authors.forename: Mário Alexandre Coelho
authors.initials: MA
authors.lastname: Sinhoreti
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry* / Q000528:radiation effects; D000818:Animals; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D003736:Dental Cavity Lining; D018772:Dental Marginal Adaptation; D003804:Dentin / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry* / Q000528:radiation effects; D011897:Random Allocation
chemical_list: D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D011140:Polyurethanes