title: Relationship between mechanical properties of one-step self-etch adhesives and water sorption.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the relationship between changes in the modulus of elasticity and ultimate tensile strength of one-step self-etch adhesives, and their degree of water sorption.
  
  
  METHODS
  Five one-step self-etch adhesives, Xeno IV (Dentsply Caulk), G Bond (GC Corp.), Clearfil S3 Bond (Kuraray Medical Inc.), Bond Force (Tokuyama Dental Corp.), and One-Up Bond F Plus (Tokuyama Dental Corp.) were used. Ten dumbelled-shaped polymers of each adhesive were used to obtain the modulus of elasticity by the three-point flexural bending test and the ultimate tensile strength by microtensile testing. The modulus of elasticity and the ultimate tensile strength were measured in both dry and wet conditions before/after immersion in water for 24h. Water sorption was measured, using a modification of the ISO-4049 standard. Each result of the modulus of elasticity and ultimate tensile strength was statistically analyzed using a two-way ANOVA and the result of water sorption was statistically analyzed using a one-way ANOVA. Regression analyses were used to determine the correlations between the modulus of elasticity and the ultimate tensile strength in dry or wet states, and also the percent decrease in these properties before/after immersion of water vs. water sorption.
  
  
  RESULTS
  In the dry state, the moduli of elasticity of the five adhesive polymers varied from 948 to 1530 MPa, while the ultimate tensile strengths varied from 24.4 to 61.5 MPa. The wet specimens gave much lower moduli of elasticity (from 584 to 1073 MPa) and ultimate tensile strengths (from 16.5 to 35.0 MPa). Water sorption varied from 32.1 to 105.8 g mm(-3).
  
  
  CONCLUSIONS
  The moduli of elasticity and ultimate tensile strengths of the adhesives fell significantly after water-storage. Water sorption depended on the constituents of the adhesive systems. The percent decreases in the ultimate tensile strengths of the adhesives were related to water sorption, while the percent reductions in the moduli of elasticity of the adhesives were not related to water sorption.
authors.affiliation: Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, Japan. hosaka.ope@tmd.ac.jp
authors.forename: Keiichi
authors.initials: K
authors.lastname: Hosaka
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Nakajima
authors.forename: Masahiro
authors.initials: M
authors.lastname: Takahashi
authors.forename: Shima
authors.initials: S
authors.lastname: Itoh
authors.forename: Masaomi
authors.initials: M
authors.lastname: Ikeda
authors.forename: Junji
authors.initials: J
authors.lastname: Tagami
authors.forename: David H
authors.initials: DH
authors.lastname: Pashley
mesh_terms: D000042:Absorption; D000134:Acid Etching, Dental / Q000379:methods; D000269:Adhesives / Q000737:chemistry*; D000704:Analysis of Variance; D003799:Dental Stress Analysis; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D055119:Elastic Modulus; D008422:Materials Testing; D011108:Polymers / Q000737:chemistry; D012044:Regression Analysis; D019279:Resin Cements / Q000737:chemistry*; D018709:Statistics, Nonparametric; D013718:Tensile Strength; D014867:Water
chemical_list: D000269:Adhesives; D017220:Dentin-Bonding Agents; D011108:Polymers; D019279:Resin Cements; D014867:Water