title: Effects of a peripheral enamel margin on the long-term bond strength and nanoleakage of composite/dentin interfaces produced by self-adhesive and conventional resin cements.
abstract: OBJECTIVE
  This study evaluated the effects of peripheral enamel margins on the long-term bond strength (µTBS) and nanoleakage in resin/dentin interfaces produced by self-adhesive and conventional resin cements.
  
  
  METHODS
  Five self-adhesive [RelyX-Unicem (UN), RelyX-U100 (UC), GCem (GC), Maxcem (MC), Set (SET)] and 2 conventional resin cements [RelyX-ARC(RX), Panavia F(PF)] were used. An additional group included the use of a two-step self-etching adhesive (SE Bond) with Panavia F (PS). One hundred ninety-two molars were assigned to 8 groups according to luting material. Five-mm-thick composite disks were cemented and assigned to 3 subgroups according to water-exposure condition (n = 6): 24-h peripheral exposure (24h-PE-enamel margins), or 1 year of peripheral (1 yr-PE) or direct exposure (1 yr-DE-dentin margin). Restored teeth were sectioned into beams and tested in tension at 1 mm/min. Data were analyzed by two-way ANOVA and Tukey's test. Two additional specimens in each group were prepared for nanoleakage evaluation. Nanoleakage patterns were observed under SEM/TEM.
  
  
  RESULTS
  Except for RX, no significant reduction in µTBS was observed between 24h-PE and 1 yr-PE. 1 yr-DE reduced µTBS for RX, PF, GC, MC, and SET. No significant reduction in µTBS was observed for PS, UC, and UN after 1 year. After 1 yr-DE, RX and PS presented the highest µTBS, and SET and MC the lowest. Nanoleakage was reduced when there was a peripheral enamel margin. SET and MC presented more silver deposition than other groups.
  
  
  CONCLUSIONS
  The presence of a peripheral enamel margin reduced the degradation rate in resin/dentin interfaces for most materials. The µTBS values produced by the multi-step luting agents RX and PS were significantly higher than those observed for self-adhesive cement.
authors.affiliation: Department of Restorative Dentistry, Guarulhos University, Guarulhos, SP, Brazil.
authors.forename: Alline C
authors.initials: AC
authors.lastname: Kasaz
authors.forename: Carlos E
authors.initials: CE
authors.lastname: Pena
authors.forename: Rodrigo S
authors.initials: RS
authors.lastname: de Alexandre
authors.forename: Ronaldo G
authors.initials: RG
authors.lastname: Viotti
authors.forename: Veronica B
authors.initials: VB
authors.lastname: Santana
authors.forename: Cesar A G
authors.initials: CA
authors.lastname: Arrais
authors.forename: Marcelo
authors.initials: M
authors.lastname: Giannini
authors.forename: Andre F
authors.initials: AF
authors.lastname: Reis
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins; D001840:Dental Bonding / Q000379:methods; D003743:Dental Enamel; D003763:Dental Leakage; D003799:Dental Stress Analysis; D003804:Dentin; D006801:Humans; D008422:Materials Testing; D008854:Microscopy, Electron; D008963:Molar; D019279:Resin Cements / Q000737:chemistry*; D018709:Statistics, Nonparametric; D013718:Tensile Strength; D014867:Water
chemical_list: D003188:Composite Resins; D019279:Resin Cements; D014867:Water