title: Mechanical viscoelastic behavior of dental adhesives.
abstract: OBJECTIVE
  The purpose of the study was to evaluate the mechanical properties of dental adhesive materials at different testing temperatures after dry and wet storage.
  
  
  METHODS
  Specimens (d=1 mm, l=18 mm) from six materials were tested: Silorane Adhesive System (SL), Heliobond (HE), One-Step Plus (OS), Optibond Solo Plus (OP), cmf Adhesive System (CF) and Protobond (PR). Static and creep testing was performed by applying a constant torque below the proportional limit of the materials, while dynamic testing consisted of dynamic torsional loading. Experiments were performed after 24h of dry and wet storage under temperatures from 21°C to 50°C and various viscoelastic parameters were calculated.
  
  
  RESULTS
  Shear modulus ranged from 0.19 to 1.99 GPa, while flexural modulus from 0.67 to 5.69 GPa. Most of the materials were affected by the presence of water and increase of temperature. OP showed the highest recovery after creep, while SL exhibited the highest permanent deformation.
  
  
  CONCLUSIONS
  Contact with water after polymerization and increase of temperature resulted in a decline of the mechanical properties, especially for the HEMA-containing adhesives.
authors.affiliation: Department of Biomaterials, School of Dentistry, National and Kapodistrian University of Athens, Athens, Greece. deminho@gmail.com
authors.forename: D
authors.initials: D
authors.lastname: Papadogiannis
authors.forename: R S
authors.initials: RS
authors.lastname: Lakes
authors.forename: Y
authors.initials: Y
authors.lastname: Papadogiannis
authors.forename: K
authors.initials: K
authors.lastname: Tolidis
mesh_terms: D000179:Acrylates / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003738:Dental Cements / Q000737:chemistry*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D055119:Elastic Modulus; D004548:Elasticity; D006801:Humans; D008422:Materials Testing; D055595:Mechanical Phenomena; D008689:Methacrylates / Q000737:chemistry; D018583:Pliability; D058105:Polymerization; D019279:Resin Cements / Q000737:chemistry; D033081:Shear Strength; D062047:Silorane Resins / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D019415:Torque; D054159:Torsion, Mechanical; D014783:Viscosity; D014867:Water / Q000737:chemistry
chemical_list: D000179:Acrylates; C103506:Bis-GMA, BPDM, HEMA dental-bonding resin; D003738:Dental Cements; D017220:Dentin-Bonding Agents; D008689:Methacrylates; C451600:OptiBond Solo Plus; D019279:Resin Cements; D062047:Silorane Resins; D014867:Water; C041979:2,2-bis-(4-(2-methacryloxyethoxy)phenyl)propane; D017438:Bisphenol A-Glycidyl Methacrylate; C040415:heliobond; C032802:hydroxypropyl methacrylate