title: Effects of Fiber-reinforced Composite Bases on Microleakage of Composite Restorations in Proximal Locations.
abstract: OBJECTIVE
  The aim of this study was to evaluate the microleakage of direct restorative composite resin upon the addition of an intermediate glass fiber-reinforced composite (GFRC) layer of various fiber orientations between tooth and particulate filler composite resin (PFRC).
  
  
  METHODS
  Cavities were prepared both on the mesial and distal surfaces of sixty extracted human molars with one margin placed below and the other above the cementoenamel junction (CEJ). Teeth were assigned to five different groups. Four of the groups received a layer of semi-interpenetrating polymer network (semi-IPN) resin system impregnated E-glass GFRC at the bottom of the cavity: Group 1; unidirectional continuous GFRC (EVS) in buccolingual direction (EVS-BL), Group 2; EVS in mesiodistal direction (EVS-MD), Group 3; bidirectional woven GFRC (EVN), Group 4; multidirectional short GFRC (EXP-MLT), Group 5; PRFC only (control). After acid etching and priming of the cavities and insertion of GFRC layer with the adhesive resin (Scotchbond Multipurpose 3M-ESPE), the cavities were filled incrementally with PRFC (Filtek Z250, 3M-ESPE) and each layer was light cured for 20 s. After finishing and polishing, the restored teeth were water-stored for 24 h at 37 °C and then thermocycled for 6000 cycles between 5-55 °C, before immersion in 0.5 % basic fuchsin dye for 24 h. After sectioning by 3-5 sagittal cuts, each sequential section was imaged and digitally analyzed to determine the stain depth.
  
  
  RESULTS
  All GFRC groups in dentin revealed significantly lower microleakage compared to control (p<0.05). The orientation of FRC intermediate layer did not reveal significant differences in microleakage (p>0.05). The microleakeage in enamel was not different between the groups (p>0.05).
  
  
  CONCLUSIONS
  Use of intermediate GFRC layer between tooth and PFRC could provide alternative method to minimize microleakage.
  
  
  CONCLUSIONS
  Use of GFRC intermediate layer underneath the particulate filler composite can be used to minimize the leakeage of the restorations.
authors.affiliation: Department of Restorative Dentistry and Cariology, Adhesive Dentistry Research Group, Institute of Dentistry, University of Turku, TYKS, Turku University Hospital, Turku, Finland.
authors.forename: Tezvergil-Mutluay
authors.initials: TM
authors.lastname: A
authors.affiliation: Department of Biomaterials Science, and Turku Clinical Biomaterials Centre - TCBC Institute of Dentistry, University of Turku, Turku, Finland.
authors.forename: Vallittu
authors.initials: V
authors.lastname: P K
keywords: Fiber-reinforced composite; fiber direction; microleakage; resin composite