title: In vitro analysis of riboflavin-modified, experimental, two-step etch-and-rinse dentin adhesive: Fourier transform infrared spectroscopy and micro-Raman studies.
abstract: To modify two-step experimental etch-and-rinse dentin adhesive with different concentrations of riboflavin and to study its effect on the bond strength, degree of conversion, along with resin infiltration within the demineralized dentin substrate, an experimental adhesive-system was modified with different concentrations of riboflavin (m/m, 0, 1%, 3%, 5% and 10%). Dentin surfaces were etched with 37% phosphoric acid, bonded with respective adhesives, restored with restorative composite-resin, and sectioned into resin-dentin slabs and beams to be stored for 24 h or 9 months in artificial saliva. Micro-tensile bond testing was performed with scanning electron microscopy to analyse the failure of debonded beams. The degree of conversion was evaluated with Fourier transform infrared spectroscopy (FTIR) at different time points along with micro-Raman spectroscopy analysis. Data was analyzed with one-way and two-way analysis of variance followed by Tukey's for pair-wise comparison. Modification with 1% and 3% riboflavin increased the micro-tensile bond strength compared to the control at 24 h and 9-month storage with no significant differences in degree of conversion (P<0.05). The most predominant failure mode was the mixed fracture among all specimens except 10% riboflavin-modified adhesive specimens where cohesive failure was predominant. Raman analysis revealed that 1% and 3% riboflavin adhesives specimens showed relatively higher resin infiltration. The incorporation of riboflavin in the experimental two-step etch-and-rinse adhesive at 3% (m/m) improved the immediate bond strengths and bond durability after 9-month storage in artificial saliva without adversely affecting the degree of conversion of the adhesive monomers and resin infiltration.
authors.affiliation: Discipline of Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore, Singapore.
authors.forename: Umer
authors.initials: U
authors.lastname: Daood
authors.affiliation: Laboratory technologist, Discipline of Oral Sciences, Biomaterials and Biophotonics, National University of Singapore, Singapore, Singapore.
authors.forename: Chan
authors.initials: C
authors.lastname: Swee Heng
authors.affiliation: Discipline of Prosthodontics, Operative Dentistry and Endodontics, National University of Singapore, Singapore, Singapore.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Neo Chiew Lian
authors.affiliation: Discipline of Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore, Singapore.
authors.forename: Amr S
authors.initials: AS
authors.lastname: Fawzy
mesh_terms: D000328:Adult; D003738:Dental Cements; D006801:Humans; D066298:In Vitro Techniques; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D012256:Riboflavin / Q000737:chemistry*; D013048:Specimen Handling; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013718:Tensile Strength; D055815:Young Adult
chemical_list: D003738:Dental Cements; D012256:Riboflavin