title: Influence of different initiators on the degree of conversion of experimental adhesive blends in relation to their hydrophilicity and solvent content.
abstract: OBJECTIVE
  The aim of this study was to compare the curing reaction of five experimental adhesive blends containing different photo-initiating systems. The hypothesis tested was that degree of conversion (DC) of resin blends is affected by resin type, solvent content and photo-initiating system.
  
  
  METHODS
  The experimental methacrylate resin blends were ranked from hydrophobic (R2) to hydrophilic (R3 and R4) and tested as neat, or solvated with 10% or 20% ethanol, or 10% ethanol and 10% water. Three different photo-initiators were used: IS-1=0.25% CQ (camphorquinone)+1% EDMAB (ethyl 4-dimethylaminobenzoate); IS-2=1.25% TPO (diphenyl(2,4,6-trimethylbenzoyl)-phosphine oxide); IS-3=0.25% CQ+0.50% EDMAB+0.50% TPO. DC of resin blends was measured with a differential scanning calorimeter. Data were analyzed with a three-way ANOVA.
  
  
  RESULTS
  Neat resin type influenced DC, as R4 showed the highest values compared to R2 and R3 (p<0.05). Solvent had a significant effect on DC (p<0.05): dilution of resin blends with 10% or 20% ethanol or 10% ethanol+10% water increased the DC of all resins, except for R4. Initiators influenced the polymerization since neat resins and mixtures solvated with 10% or 20% ethanol showed their highest DC values when polymerized with IS-1 or IS-3 (p>0.05), while IS-2 or IS-3 increased the DC values of resins diluted with 10% ethanol and 10% water (p<0.05).
  
  
  CONCLUSIONS
  Water-compatible photo-initiators such as TPO should be included in the hydrophilic solvated adhesive formulation to ensure an appropriate DC of the adhesive layer.
authors.affiliation: Unit of Dental Sciences and Biomaterials, Department of Biomedicine, University of Trieste, Piazza Ospedale 1, Trieste, Italy.
authors.forename: Milena
authors.initials: M
authors.lastname: Cadenaro
authors.forename: Francesca
authors.initials: F
authors.lastname: Antoniolli
authors.forename: Barbara
authors.initials: B
authors.lastname: Codan
authors.forename: Kelli
authors.initials: K
authors.lastname: Agee
authors.forename: Franklin R
authors.initials: FR
authors.lastname: Tay
authors.forename: Elettra De Stefano
authors.initials: Ede S
authors.lastname: Dorigo
authors.forename: David H
authors.initials: DH
authors.lastname: Pashley
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Breschi
mesh_terms: D000704:Analysis of Variance; D002152:Calorimetry, Differential Scanning; D017220:Dentin-Bonding Agents / Q000737:chemistry* / Q000528:radiation effects; D000431:Ethanol; D006244:Hardness; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D044367:Phase Transition; D010720:Phosphines; D019279:Resin Cements / Q000737:chemistry* / Q000528:radiation effects; D012997:Solvents; D013729:Terpenes; D014867:Water; D017155:Wettability
chemical_list: C520678:(2,4,6-trimethylbenzoyl) diphenylphosphine oxide; D017220:Dentin-Bonding Agents; D010720:Phosphines; D019279:Resin Cements; D012997:Solvents; D013729:Terpenes; D014867:Water; D000431:Ethanol; C048339:camphoroquinone