title: Hydrolytic degradation of the resin-dentine interface induced by the simulated pulpal pressure, direct and indirect water ageing.
abstract: OBJECTIVE
  The aim of this study was to compare the hydrolytic effects induced by simulated pulpal pressure, direct or indirect water exposure within the resin-dentine interfaces created with three "simplified" resin bonding systems (RBSs).
  
  
  METHODS
  A two-step/self-etching (CSE: Clearfil SE Bond), one-step/self-etching (S3: Clearfil S3) and etch-and-rinse/self-priming (SB: Single-bond 2) adhesives were applied onto dentine and submitted to three different prolonged (6 or 12 months) ageing strategies: (i) Simulated Pulpal Pressure (SPP); (ii) Indirect Water Exposure (IWE: intact bonded-teeth); (iii) Direct Water Exposure (DWE: resin-dentine sticks). Control and aged specimens were submitted to microtensile bond strength (μTBS) and nanoleakage evaluation. Water sorption (WS) survey was also performed on resin disks. Results were analysed with two-way ANOVA and Tukey's test (p < 0.05).
  
  
  RESULTS
  The μTBS of CS3 and SB dropped significantly (p < 0.05) after 6 months of SPP and DWE. CSE showed a significant μTBS reduction only after 12 months of DWE (p = 0.038). IWE promoted no statistical change in μTBS (p > 0.05) and no evident change in nanoleakage. Conversely, SPP induced a clear formation of "water-trees" in CS3 and SB. WS outcomes were CS3 > SB = CSE.
  
  
  CONCLUSIONS
  The hydrolytic degradation of resin-dentine interfaces depend upon the type of the in vitro ageing strategy employed in the experimental design. Direct water exposure remains the quickest method to age the resin-dentine bonds. However, the use of SPP may better simulate the in vivo scenario. However, the application of a separate hydrophobic solvent-free adhesive layer may reduce the hydrolytic degradation and increase the longevity of resin-dentine interfaces created with simplified adhesives.
authors.affiliation: Department of Restorative Dentistry, Division of Dental Materials, Piracicaba Dental School, State University of Campinas, Av. Limeira 901, Piracicaba 13414-903, SP, Brazil. victorpfeitosa@hotmail.com
authors.forename: Victor P
authors.initials: VP
authors.lastname: Feitosa
authors.forename: Ariene A
authors.initials: AA
authors.lastname: Leme
authors.forename: Salvatore
authors.initials: S
authors.lastname: Sauro
authors.forename: Lourenço
authors.initials: L
authors.lastname: Correr-Sobrinho
authors.forename: Timothy F
authors.initials: TF
authors.lastname: Watson
authors.forename: Mário A
authors.initials: MA
authors.lastname: Sinhoreti
authors.forename: Américo B
authors.initials: AB
authors.lastname: Correr
mesh_terms: D000042:Absorption; D000327:Adsorption; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry; D003763:Dental Leakage / Q000145:classification; D003782:Dental Pulp / Q000502:physiology*; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D006868:Hydrolysis; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011312:Pressure; D019279:Resin Cements / Q000737:chemistry*; D016622:Silver Staining; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013718:Tensile Strength; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: C554641:Adper single bond 2; C505694:Clearfil S3 Bond; C438313:Clearfil SE Bond; D003188:Composite Resins; D003738:Dental Cements; D017220:Dentin-Bonding Agents; D019279:Resin Cements; C533204:filtek Z350; D014867:Water