title: Degree of conversion of resin blends in relation to ethanol content and hydrophilicity.
abstract: OBJECTIVE
  To evaluate the degree of conversion of five experimental adhesive systems in relation to their hydrophilicity. The resin blends ranged from hydrophobic to hydrophilic and were tested as neat bonding agents, or solvated with increasing percentages of ethanol. The hypothesis tested was that extent of polymerization of resin blends is affected by resin hydrophilicity, solvent concentrations or time of polymerization.
  
  
  METHODS
  Five light-curing versions of neat experimental resin blends were submitted to investigation: (1) 70% E-BisADM, 28.75% TEGDMA; (2) 70% BisGMA, 28.7% TEGDMA; (3) 70% BisGMA, 28.7% HEMA; (4) 40% BisGMA, 30% TCDM, and 28.75% TEGDMA; (5) 40% BisGMA, 30% BisMP, and 28.75% HEMA. All blends included 1% EDMAB and 0.25% CQ. Ethanol in different weight percentages (A: 0%, B: 30%, C: 50%, D: 70% and E: 90%) was added to these resin blends simulating different formulation of adhesives. A differential scanning calorimeter was used to measure the degree of conversion of resin blends as a function of resin hydrophilicity, solvent concentration and time of curing. Data were analyzed with three-way ANOVA and Tukey's post hoc test.
  
  
  RESULTS
  Exotherms showed that degree of conversion was influenced by the hydrophilicity of the blends resin (p<.05), percentage of ethanol dilution (p<.05) and time of curing (p<.05). 30% ethanol dilution increased degree of conversion compared to neat compounds irrespective to resin type and curing time, showing the highest degree of conversion values of the study design.
  
  
  CONCLUSIONS
  This study supports the hypothesis that high ethanol percentages (>50mass%) may compromise extent of polymerization kinetics of dental adhesives.
authors.affiliation: Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Via Stuparich 1, I-34125 Trieste, Italy. m.cadenaro@fmc.units.it
authors.forename: Milena
authors.initials: M
authors.lastname: Cadenaro
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Breschi
authors.forename: Francesca
authors.initials: F
authors.lastname: Antoniolli
authors.forename: Chiara O
authors.initials: CO
authors.lastname: Navarra
authors.forename: Annalisa
authors.initials: A
authors.lastname: Mazzoni
authors.forename: Franklin R
authors.initials: FR
authors.lastname: Tay
authors.forename: Roberto
authors.initials: R
authors.lastname: Di Lenarda
authors.forename: David H
authors.initials: DH
authors.lastname: Pashley
mesh_terms: D010129:4-Aminobenzoic Acid / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D000431:Ethanol / Q000737:chemistry*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D012997:Solvents / Q000737:chemistry*; D013696:Temperature; D013729:Terpenes / Q000737:chemistry; D013997:Time Factors; D014867:Water / Q000737:chemistry; D017155:Wettability; D062366:para-Aminobenzoates
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D008689:Methacrylates; D011108:Polymers; D011109:Polymethacrylic Acids; D012997:Solvents; D013729:Terpenes; C523330:ethyl 4-N,N-dimethylaminobenzoate; C114321:methacryloxyethyl dihydrogen phosphate; D062366:para-Aminobenzoates; D014867:Water; C020946:triethylene glycol dimethacrylate; D000431:Ethanol; D011092:Polyethylene Glycols; C074277:ethoxylated bis-phenol A dimethacrylate; D017438:Bisphenol A-Glycidyl Methacrylate; C048339:camphoroquinone; C005044:hydroxyethyl methacrylate; D010129:4-Aminobenzoic Acid