title: Diffusion and concurrent solubility of self-adhering and new resin-matrix composites during water sorption/desorption cycles.
abstract: OBJECTIVE
  To investigate the kinetic process of water diffusion and mass change in new resin-matrix composites during water sorption/desorption cycles.
  
  
  METHODS
  Five new resin-matrix composites were investigated [Filtek(®) Silorane (FS), GC Gradia Direct Anterior (GDA), GC Gradia Direct Posterior (GDP), GC Kalore (GCK), Vertise(®) Flow (VF)]. Five disk-shaped specimens, per material (15.0±0.1) mm diameter by (2.0±0.1) mm, were prepared according to ISO 4049. Each disk was immersed separately in de-ionized water for 150 d and then reconditioned for 75 d; all at (37±1)°C. Mass was measured at different time intervals. Perspex disks were used as control. Data analysis was done by repeated measures ANOVA, one-way ANOVA and Tukey's post hoc test (p<0.05).
  
  
  RESULTS
  The water sorption (μg/mm³) after 150 d immersion ranged from 13.51 μg/mm³ (±0.40) for FS to 71.96 μg/mm³ (±0.90) for VF. The solubility ranged up to 16.95 μg/mm³ (±0.79) for VF. A significant mass reduction occurred in VF after the peak value [73.63 μg/mm³ (±0.31)] of water sorption was reached at 42 d. VF had the highest diffusion-coefficient for sorption: 5.23×10⁻⁹ cm²/s (±0.38) and desorption: 11.72×10⁻⁹ cm²/s (±0.16). Percentage sorption differences were significant for all materials (p<0.001), except between GCK and GDP. The early correlation between mass change and square root of time was linear.
  
  
  CONCLUSIONS
  Each resin-matrix composite varied in sorption/desorption cycles which may affect clinical service. A concurrent solubility process occurred during sorption of the self-adhering composite VF. The silorane composite FS exhibited minimal sorption.
authors.affiliation: Department of Prosthodontics, School of Stomatology, Capital Medical University, Tiantan Xili No. 4, Chongwen District, Beijing 100050, PR China.
authors.forename: Yong-jie
authors.initials: YJ
authors.lastname: Wei
authors.forename: Nick
authors.initials: N
authors.lastname: Silikas
authors.forename: Zhen-ting
authors.initials: ZT
authors.lastname: Zhang
authors.forename: David C
authors.initials: DC
authors.lastname: Watts
mesh_terms: D000042:Absorption; D000327:Adsorption; D055598:Chemical Phenomena; D003188:Composite Resins / Q000737:chemistry*; D055117:Curing Lights, Dental; D003764:Dental Materials / Q000737:chemistry*; D004058:Diffusion; D006801:Humans; D006813:Humidity; D008422:Materials Testing; D062047:Silorane Resins; D012833:Siloxanes / Q000737:chemistry; D012995:Solubility; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry*
chemical_list: D003188:Composite Resins; D003764:Dental Materials; C470230:Gradia; D062047:Silorane Resins; D012833:Siloxanes; C555513:silorane composite resin; D014867:Water