IADR Abstract Archives
Effect of Residual Solvent on Performance of Acrylamide-Containing Dental Materials
Objectives: Acrylamide-based monomers are being pursued as hydrolytically stable materials in dental resin-composites and adhesives.
Methods: 70wt% BisGMA HEMAM-BDI (newly synthesized secondary methacrylamide) were combined with 30wt% N,N-dimethylacrylamide. Solvents (ethyl acetate, EtOAc, or 75/25 ethanolwater, EtOH/H2O) were added according to the table. 0.2wt% 2,2-dimethoxy-2-phenyl-acetophenone, 0.4wt% diphenyliodonium hexafluorophosphate, and 0.1wt% butylated hydroxytoluene were added. Samples (n=3) were photoactivated with a mercury arc lamp (320-500nm, 250mW/cm2) for 5 min. Degree of conversion (DC, %) was tracked in near-IR (~6165cm-1). Flexural strength (FS, MPa) at 48hrs (n=5) was determined by three-point bending in bar specimens (2x2x25 mm), irradiated for 2 min on each side, , followed by 10 min post-curing (200mW/cm2). Data was analyzed with one-way ANOVA/Tukey's test (95%).
Results: In all groups, DC increased and maximum rate of polymerization (Rpmax) decreased as solvent concentration increased. Despite the increased DC, BisGMA mixtures showed a decrease in FS starting at 5wt% EtOAc or 15wt% EtOH/H2O whereas HEMAM-BDI showed a significant decrease only with 20wt% EtOH/H2O. FS for HEMAM-BDI groups was overall lower than the BisGMA groups.
Conclusions: Presence of residual solvent, from manufacturing or from practitioner’s handling, affects polymerization kinetics and mechanical properties. Methacrylates appear to be more strongly influenced than methacrylamides.
Methods: 70wt% BisGMA HEMAM-BDI (newly synthesized secondary methacrylamide) were combined with 30wt% N,N-dimethylacrylamide. Solvents (ethyl acetate, EtOAc, or 75/25 ethanolwater, EtOH/H2O) were added according to the table. 0.2wt% 2,2-dimethoxy-2-phenyl-acetophenone, 0.4wt% diphenyliodonium hexafluorophosphate, and 0.1wt% butylated hydroxytoluene were added. Samples (n=3) were photoactivated with a mercury arc lamp (320-500nm, 250mW/cm2) for 5 min. Degree of conversion (DC, %) was tracked in near-IR (~6165cm-1). Flexural strength (FS, MPa) at 48hrs (n=5) was determined by three-point bending in bar specimens (2x2x25 mm), irradiated for 2 min on each side, , followed by 10 min post-curing (200mW/cm2). Data was analyzed with one-way ANOVA/Tukey's test (95%).
Results: In all groups, DC increased and maximum rate of polymerization (Rpmax) decreased as solvent concentration increased. Despite the increased DC, BisGMA mixtures showed a decrease in FS starting at 5wt% EtOAc or 15wt% EtOH/H2O whereas HEMAM-BDI showed a significant decrease only with 20wt% EtOH/H2O. FS for HEMAM-BDI groups was overall lower than the BisGMA groups.
Conclusions: Presence of residual solvent, from manufacturing or from practitioner’s handling, affects polymerization kinetics and mechanical properties. Methacrylates appear to be more strongly influenced than methacrylamides.
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