Modelling ATR-FTIR Spectra of Dental Bonding Systems to Investigate Composition and Polymerisation Kinetics

Component ratios and kinetics are key to understanding and optimising novel formulations. This warrants investigation of valid methods. Attenuated Total Reflectance Fourier Transform Infra-Red (ATR)-FTIR spectra of separate primers/adhesives were modelled using summed spectra of solvents (water, eth...

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Bibliographic Details
Published in:Materials 2021-02, Vol.14 (4), p.760
Main Authors: Delgado, António Hs, Young, Anne M
Format: Article
Language:English
Subjects:
Adhesives
Bisphenol A glycidyl methacrylate
Bond strength
Bonding
Conversion
Ethanol
Fillers
Fourier transforms
Hydroxyapatite
Infrared spectroscopy
Kinetics
Light emitting diodes
Modelling
Molecular weight
Monomers
Polyhydroxyethyl methacrylate
Polymerization
Ratios
Software
Solvents
Spectra
Statistical analysis
Statistical methods
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Summary:Component ratios and kinetics are key to understanding and optimising novel formulations. This warrants investigation of valid methods. Attenuated Total Reflectance Fourier Transform Infra-Red (ATR)-FTIR spectra of separate primers/adhesives were modelled using summed spectra of solvents (water, ethanol), methacrylate monomers (HEMA (hydroxyethyl methacrylate), Bis-GMA (bisphenol A glycidyl methacrylate), and 10-MDP (10-methacryloyloxydecyl dihydrogen phosphate)), and fillers, multiplied by varying fractions. Filler loads were obtained following their separation from the adhesives, by analysing three repetitions ( = 3). Spectral changes during light exposure at 37 °C (20 s, LED 1100-1330 mW/cm ) were used to determine polymerisation kinetics ( = 3). Independent samples T-test was used for statistical analysis (significance level of 5%). FTIR modelling suggested a primer solvent percentage of OBFL (Optibond FL) (30%) was half that of CFSE (Clearfil SE 2) (60%). OBFL included ethanol and water, while CFSE included only water. Monomer peaks were largely those of HEMA with lower levels of phosphate monomers. OBFL/CFSE adhesive model spectra suggested that both contained equal volumes of Bis-GMA/HEMA, with CFSE having 10-MDP. Filler levels and spectra from OBFL (48 wt.%) and CFSE (5 wt.%) were different. Both systems reached a 50% conversion rate within seconds of light exposure. The final conversion for OBFL (74 ± 1%) was lower compared to CFSE (79 ± 2%) ( < 0.05). ATR-FTIR is a useful method to investigate relative levels of main components in bonding systems and their polymerisation kinetics. Such information is valuable to understanding such behaviour.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma14040760