title: Effect of temperature on water sorption and solubility of dental adhesive resins.
abstract: OBJECTIVE
  This study examined the effect of temperature on water sorption and solubility characteristics of four commercial dental adhesives. The null hypothesis tested was that temperature has no effect on the water sorption and solubility characteristics of these adhesives.
  
  
  METHODS
  The tested materials were: three-step etch-and-rinse (All-Bond 2, AB), two-step etch-and-rinse (One-Step, OS), two-step self-etch (Clearfil SE Bond, SE) and one-step self-etch (Clearfil S3 Bond, S3) adhesives. Seven resin disks (6mm in diameterx1mm in thickness) were prepared from each tested material and were stored in deionized water at 23 degrees C, 37 degrees C and 55 degrees C. Water sorption and solubility of the resin disks were measured before and after water immersion and desiccation following two consecutive sorption and desorption cycles. The water sorption and solubility values obtained were analyzed using two-way ANOVA and Tukey's multiple comparison tests. The relationships between maximum water sorption, solubility and kinetics of water diffusion with temperature were evaluated by means of Pearson correlation statistic.
  
  
  RESULTS
  OS exhibited the highest water sorption and solubility values in the second sorption-desorption cycle at 55 degrees C (p<0.001). This is followed by S3, SE and AB with no significant difference between SE and AB. Significant positive correlations were observed between maximum water sorption (r=0.307, p<0.01), solubility (r=0.244, p<0.05), water sorption (r=0.651, p<0.001) and desorption (r=0.733, p<0.001) diffusion coefficients (obtained using Fick's law of diffusion) with temperature in the second cycle.
  
  
  CONCLUSIONS
  High temperatures increased water sorption of simplified adhesives. Such water sorption may contribute to the failure of resin-dentin bonds.
authors.affiliation: Paediatric Dentistry and Orthodontics, Faculty of Dentistry, The University of Hong Kong, Prince Philip Dental Hospital, 34 Hospital Road, Hong Kong, SAR, China.
authors.forename: P
authors.initials: P
authors.lastname: Dhanpal
authors.forename: C K Y
authors.initials: CK
authors.lastname: Yiu
authors.forename: N M
authors.initials: NM
authors.lastname: King
authors.forename: F R
authors.initials: FR
authors.lastname: Tay
authors.forename: N
authors.initials: N
authors.lastname: Hiraishi
mesh_terms: D000042:Absorption; D000327:Adsorption; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D003890:Desiccation; D004058:Diffusion; D006801:Humans; D006813:Humidity; D007101:Immersion; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008956:Models, Chemical; D019279:Resin Cements / Q000737:chemistry; D012995:Solubility; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry*
chemical_list: C103506:Bis-GMA, BPDM, HEMA dental-bonding resin; C505694:Clearfil S3 Bond; C438313:Clearfil SE Bond; D017220:Dentin-Bonding Agents; D008689:Methacrylates; D019279:Resin Cements; D014867:Water; C100742:All-Bond 2