title: The influence of chemical structure on the properties in methacrylate-based dentin adhesives.
abstract: OBJECTIVE
  The objective of this study was to investigate the influence of the chemical structure of methacrylate monomers used in dentin adhesives on degree of conversion (DC), water sorption, and dynamic mechanical properties.
  
  
  METHODS
  Experimental adhesives containing 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy) phenyl]-propane (BisGMA), 2-hydroxyethyl methacrylate (HEMA), and co-monomer, 30/45/25 (w/w) were photo-polymerized. Ethyleneglycol dimethacrylate (EGDM), diethyleneglycol dimethacrylate (DEGDM), triethyleneglycol dimethacrylate (TEGDMA), 1,3-glycerol dimethacrylate (GDM), and glycerol trimethacrylate (GTM) were used as a co-monomer. The adhesives were characterized with regard to DC, water sorption, and dynamic mechanical analysis and compared to control adhesive [HEMA/BisGMA, 45/55 (w/w)].
  
  
  RESULTS
  DC and water sorption increased with an increase in the number of ethylene glycol units in the monomer. Experimental adhesive containing GDM showed significantly higher storage moduli (p<0.05) in both dry and wet samples than experimental adhesives containing EGDM or DEGDM. The rubbery moduli of adhesives containing GDM and GTM were found to be significantly greater (p<0.05) than that of the control. Adhesives containing GTM exhibited the widest tanδ curves, indicating the greatest structural heterogeneity.
  
  
  CONCLUSIONS
  The hydrophilicity, functionality and size of monomers in dentin adhesives affected the water sorption, solubility, crosslink density and heterogeneity of the polymer network. The experimental adhesives containing GDM and GTM showed higher rubbery moduli, indicating higher crosslink density accompanied by a decrease in the homogeneity of the polymer network structure.
authors.affiliation: Bioengineering Research Center, School of Engineering, University of Kansas, Lawrence, KS, USA.
authors.forename: Jonggu
authors.initials: J
authors.lastname: Park
authors.forename: John
authors.initials: J
authors.lastname: Eslick
authors.forename: Qiang
authors.initials: Q
authors.lastname: Ye
authors.forename: Anil
authors.initials: A
authors.lastname: Misra
authors.forename: Paulette
authors.initials: P
authors.lastname: Spencer
mesh_terms: D000042:Absorption; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D019855:Ethylene Glycol / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008422:Materials Testing; D055595:Mechanical Phenomena; D008689:Methacrylates / Q000737:chemistry*; D015394:Molecular Structure; D058567:Photoinitiators, Dental; D011092:Polyethylene Glycols / Q000737:chemistry; D058105:Polymerization; D011109:Polymethacrylic Acids / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D012995:Solubility; D013329:Structure-Activity Relationship; D014867:Water
chemical_list: D017220:Dentin-Bonding Agents; D008689:Methacrylates; D058567:Photoinitiators, Dental; D011109:Polymethacrylic Acids; D011140:Polyurethanes; D019279:Resin Cements; D014867:Water; C029824:urethane dimethacrylate luting resin; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; C005044:hydroxyethyl methacrylate; D019855:Ethylene Glycol