title: Monomer-to-polymer conversion and micro-tensile bond strength to dentine of experimental and commercial adhesives containing diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide or a camphorquinone/amine photo-initiator system.
abstract: OBJECTIVE
  To compare the degree of conversion (DC) of adhesives initiated by diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) or a camphorquinone/tertiary amine system (CQ/Amine) as well as their 'immediate' micro-tensile bond strength (μTBS) to bur-cut dentine.
  
  
  METHODS
  DC of Scotchbond Universal ('SBU'; 3M ESPE), its experimental counterpart containing TPO as photo-initiator system, an experimental G-aenial Bond ('Ga-B'; GC) adhesive formulation, and an experimental LUB-102 adhesive formulation ('LUB', Kuraray Noritake), containing as photo-initiatior system either 2wt% CQ along with 2wt% tertiary amine ('SBU_CQ/Amine'; 'Ga-B_CQ/Amine'; 'LUB_CQ/Amine'), or 2wt% TPO ('SBU_TPO'; 'Ga-B_TPO'; 'LUB_TPO'), was determined using Fourier-transform infrared spectroscopy (FTIR), after being cured with a dual-wavelength light-curing unit (bluephase 20i, Ivoclar Vivadent). The same adhesive formulations were applied to bur-cut mid-coronal dentine of intact human molars, and subjected to a μTBS test after 1-week water storage. Besides being applied following a self-etch (SE) application mode, the adhesive formulations SBU_CQ/Amine and SBU_TPO were also applied following an etch-and-rinse (E&R) mode, this both for DS and μTBS measurement.
  
  
  RESULTS
  No significant difference in DC was found for any of the adhesive formulations, except for SBU_CQ/Amine_SE and SBU_TPO_SE. For both SBU formulations, a significantly higher DC was reached for the E&R than the SE approach. Regarding μTBS, no significant differences were recorded, except for the significantly higher μTBS measured for SBU_CQ/Amine_E&R and SBU_TPO_E&R.
  
  
  CONCLUSIONS
  In self-etch adhesives, the photo-initiator TPO may be used instead of CQ/Amine. The curing and 'immediate' bonding efficiency depended on the application protocol (E&R versus SE), but not on the photo-initiator system.
  
  
  CONCLUSIONS
  The photo-initiator TPO may be used in self-etch adhesives instead of CQ/Amine with similar curing and 'immediate' bonding efficiency.
authors.affiliation: KU Leuven BIOMAT, Department of Oral Health Sciences, KU Leuven (University of Leuven), Belgium; University of Belgrade, School of Dental Medicine, Belgrade, Serbia. Electronic address: vesna.miletic@stomf.bg.ac.rs.
authors.forename: Vesna
authors.initials: V
authors.lastname: Miletic
authors.forename: Pong
authors.initials: P
authors.lastname: Pongprueksa
authors.forename: Jan
authors.initials: J
authors.lastname: De Munck
authors.forename: Neil R
authors.initials: NR
authors.lastname: Brooks
authors.forename: Bart
authors.initials: B
authors.lastname: Van Meerbeek
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D000328:Adult; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002164:Camphor / Q000031:analogs & derivatives* / Q000737:chemistry; D055117:Curing Lights, Dental / Q000145:classification; D001840:Dental Bonding; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D055115:Light-Curing of Dental Adhesives / Q000295:instrumentation; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D009943:Organophosphorus Compounds / Q000737:chemistry; D010720:Phosphines / Q000737:chemistry*; D058567:Photoinitiators, Dental / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D058105:Polymerization; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013314:Stress, Mechanical; D013718:Tensile Strength; D013997:Time Factors; D014867:Water / Q000737:chemistry; D055815:Young Adult; D062366:para-Aminobenzoates / Q000737:chemistry
chemical_list: C520678:(2,4,6-trimethylbenzoyl) diphenylphosphine oxide; D017220:Dentin-Bonding Agents; C498353:G-Bond; C074230:MDP adhesion promoting monomer; D008689:Methacrylates; D009943:Organophosphorus Compounds; D010720:Phosphines; D058567:Photoinitiators, Dental; D011109:Polymethacrylic Acids; D019279:Resin Cements; C523330:ethyl 4-N,N-dimethylaminobenzoate; D062366:para-Aminobenzoates; D014867:Water; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; C005044:hydroxyethyl methacrylate; D002164:Camphor; C041330:Scotchbond; C553149:camphorquinone
keywords: Adhesive; Bond strength; Degree of conversion; Dentine; FTIR; TPO