title: Degree of conversion and monomer elution of CQ/amine and TPO adhesives.
abstract: OBJECTIVE
  To evaluate the effect of photo-initiator on the degree of conversion (DC) and elution of Bis-GMA and HEMA for 8 one-step adhesive formulations.
  
  
  METHODS
  We used Scotchbond Universal ('SBU-CQ/amine_4.0', 3M ESPE), containing about 2wt% camphorquinone (CQ) and 2wt% ethyl-4-dimethylamino benzoate (EDMAB), an experimental 'SBU-TPO_2.1' version, containing 2.1wt% diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), and 6 experimental LUB adhesives (Kuraray Noritake), namely 'LUB-CQ/amine_0.7', 'LUB-CQ/amine_1.4', 'LUB-CQ/amine_4.0', 'LUB-TPO_0.35', 'LUB-TPO_0.7' and 'LUB-TPO_2.0', respectively containing 0.35wt% CQ and 0.35wt% EDMAB, 0.7wt% CQ and 0.7wt% EDMAB, 2.0wt% CQ and 2.0wt% EDMAB, 0.35wt% TPO, 0.7wt% TPO, and 2.0wt% TPO. DC was measured using micro-Raman spectroscopy. Additional specimens were immersed in ethanol for 24h to determine the elution of Bis-GMA and HEMA using HPLC.
  
  
  RESULTS
  DC of the respective SBU and LUB adhesives was alike at high photo-initiator concentration. At low concentration, TPO was significantly more efficient than CQ/amine (LUB adhesives only). A statistically significant positive photo-initiator concentration effect on DC was noted for both CQ/amine and TPO (LUB adhesives only). A statistically significant inverse photo-initiator concentration effect on HEMA elution was noted for both the CQ/amine- and TPO-containing LUB adhesives. A significantly strong correlation was found between DC and Bis-GMA elution (R(2)=0.744, p=0.026), and between DC and HEMA elution (R(2)=0.913, p=0.002) for the LUB adhesives.
  
  
  CONCLUSIONS
  The photo-initiator kind and concentration affect DC and the Bis-GMA/HEMA elution. TPO can be used as an alternative photo-initiator for CQ/amine.
authors.affiliation: KU Leuven BIOMAT, Department of Oral Health Sciences, KU Leuven (University of Leuven) & Dentistry, University Hospitals Leuven, Belgium; Department of Operative Dentistry and Endodontics, Faculty of Dentistry, Mahidol University, Bangkok, Thailand.
authors.forename: Pong
authors.initials: P
authors.lastname: Pongprueksa
authors.affiliation: KU Leuven BIOMAT, Department of Oral Health Sciences, KU Leuven (University of Leuven) & Dentistry, University Hospitals Leuven, Belgium; University of Belgrade, School of Dental Medicine, Belgrade, Serbia.
authors.forename: Vesna
authors.initials: V
authors.lastname: Miletic
authors.affiliation: Laboratory of Occupational and Environmental Hygiene, Department of Public Health and Primary Care, KU Leuven (University of Leuven), Leuven, Belgium.
authors.forename: Henriette
authors.initials: H
authors.lastname: Janssens
authors.affiliation: KU Leuven BIOMAT, Department of Oral Health Sciences, KU Leuven (University of Leuven) & Dentistry, University Hospitals Leuven, Belgium.
authors.forename: Kirsten L
authors.initials: KL
authors.lastname: Van Landuyt
authors.affiliation: KU Leuven BIOMAT, Department of Oral Health Sciences, KU Leuven (University of Leuven) & Dentistry, University Hospitals Leuven, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: De Munck
authors.affiliation: Laboratory of Occupational and Environmental Hygiene, Department of Public Health and Primary Care, KU Leuven (University of Leuven), Leuven, Belgium.
authors.forename: Lode
authors.initials: L
authors.lastname: Godderis
authors.affiliation: KU Leuven BIOMAT, Department of Oral Health Sciences, KU Leuven (University of Leuven) & Dentistry, University Hospitals Leuven, Belgium. Electronic address: bart.vanmeerbeek@med.kuleuven.be.
authors.forename: Bart
authors.initials: B
authors.lastname: Van Meerbeek
mesh_terms: D000588:Amines / Q000737:chemistry*; D002164:Camphor / Q000031:analogs & derivatives* / Q000737:chemistry; D003738:Dental Cements / Q000737:chemistry*; D010720:Phosphines / Q000737:chemistry*
chemical_list: C520678:(2,4,6-trimethylbenzoyl) diphenylphosphine oxide; D000588:Amines; D003738:Dental Cements; D010720:Phosphines; D002164:Camphor; C553149:camphorquinone
keywords: Bis-GMA; CQ/amine; Degree of conversion; HEMA; Monomer elution; TPO