IADR Abstract Archives
Analysis of Monomers Released from Resin-Modified Glass Ionomer Cements (RMGICs).
Objectives: To analyse residual monomers in deionised water (DW) and 75:25% ethanol:DW released from commercial and experimental RMGICs.
Methods: Two commercial RMGICs were included: Fuji-Plus (GC, Japan) and RelyX-Luting (3M-ESPE, USA). Two additional in-house liquids were prepared based on their formulations. Eight experimental liquid compositions (F1- F4 based on Fuji-Plus; R1- R4 based on RelyX-Luting) were prepared replacing 100% of hydroxyethyl-methacrylate (HEMA) with hydroxypropyl-methacrylate (HPM) in F1 and R1, or 70%/30% HPM/ tetrahydrofurfuryl-methacrylate (THFM) in F2 and R2, 50%/50% THFM/HEMA in F3 and R3 and 30%/70% THFM/HEMA in F4 and R4. Two novel HPLC methods were developed. Twelve discs (10mm-diameter, 1mm-thick) were prepared for each RMGIC and immersed separately in 10 ml of solution (DW or ethanol:DW). 1mL of immersion solution was extracted after 1, 4, 24 and 168-hours. Calibration curves were created using standard solutions containing known amounts of each monomer. Measurements were taken twice for each of the extracted and calibration solutions, and the mean of the peak heights was calculated. Gradient conditions with acetonitrile and DW were used as the mobile phase.
Results: Very small amounts (≤0.5 ppm) of residual monomers were identifiable by the two novel HPLC methods. Lower amounts of HEMA were released from F3 and F4 compared to Fuji-Plus after 1 hour (p≤0.0001). F1 showed higher release of monomers (reaching 284.10 ppm) compared to all materials in the same group at all time points in both solutions (p≤0.001). RelyX-Luting released more HEMA than experimental R materials at all time points in DW (p≤0.015), and more than R3 and R4 in ethanol:DW (p≤0.005).
Conclusions: Novel HPLC methods were successful in identifying monomers released from RMGICs. Compositions containing THFM showed similar or lower release of monomers compared to commercial and experimental RMGICs in both solutions, thus indicating a higher, or similar degree of polymerisation.
Methods: Two commercial RMGICs were included: Fuji-Plus (GC, Japan) and RelyX-Luting (3M-ESPE, USA). Two additional in-house liquids were prepared based on their formulations. Eight experimental liquid compositions (F1- F4 based on Fuji-Plus; R1- R4 based on RelyX-Luting) were prepared replacing 100% of hydroxyethyl-methacrylate (HEMA) with hydroxypropyl-methacrylate (HPM) in F1 and R1, or 70%/30% HPM/ tetrahydrofurfuryl-methacrylate (THFM) in F2 and R2, 50%/50% THFM/HEMA in F3 and R3 and 30%/70% THFM/HEMA in F4 and R4. Two novel HPLC methods were developed. Twelve discs (10mm-diameter, 1mm-thick) were prepared for each RMGIC and immersed separately in 10 ml of solution (DW or ethanol:DW). 1mL of immersion solution was extracted after 1, 4, 24 and 168-hours. Calibration curves were created using standard solutions containing known amounts of each monomer. Measurements were taken twice for each of the extracted and calibration solutions, and the mean of the peak heights was calculated. Gradient conditions with acetonitrile and DW were used as the mobile phase.
Results: Very small amounts (≤0.5 ppm) of residual monomers were identifiable by the two novel HPLC methods. Lower amounts of HEMA were released from F3 and F4 compared to Fuji-Plus after 1 hour (p≤0.0001). F1 showed higher release of monomers (reaching 284.10 ppm) compared to all materials in the same group at all time points in both solutions (p≤0.001). RelyX-Luting released more HEMA than experimental R materials at all time points in DW (p≤0.015), and more than R3 and R4 in ethanol:DW (p≤0.005).
Conclusions: Novel HPLC methods were successful in identifying monomers released from RMGICs. Compositions containing THFM showed similar or lower release of monomers compared to commercial and experimental RMGICs in both solutions, thus indicating a higher, or similar degree of polymerisation.