IADR Abstract Archives
A Novel Hybrid Oxirane-Acrylate Restorative System
Objectives: To develop a hydrophobic, degradation-resistant restorative system containing a hybrid Oxirane/Acrylate System (OASys), with the goal of doubling the clinical lifetime of current restorative systems.
Methods: A novel monomer blend containing 25% urethane diacrylate (UDA), 25% urethane dioxirane, and 50% hybrid urethane acrylate oxirane (UAO) was synthesized. Resins made with this blend contain 50% acrylate and 50% oxirane groups. Resins were also made with varying concentrations of this blend and UDA or p-cycloaliphatic diepoxide (Epalloy-5000) to form resins with 25% acrylate:75% oxirane, and 75% acrylate:25% oxirane. Resins were also made with Epalloy (100% oxirane) or 100% UDA alone. Control was 70:30 Bis-GMA:TEGDMA resin. A novel 2-component initiator system capable of free radical and cationic initiation containing 4-Isopropyl-4'-methyldiphenyliodonium tetrakis borate and camphorquinone was optimized together with an oligomeric diol (polytetrahydrofuran) for these monomer blends. Resins were light-cured and tested for degree of cure (Durometer-D hardness), hydrophobicity (contact angle goniometry), and near-IR FTIR (NIR) degree of conversion.
Results: All experimental groups were significantly more hydrophobic than the control. Interestingly, the 25% oxirane group was most hydrophobic. However, hardness decreased as oxirane content increased, but the 25% oxirane group had comparable hardness to the control. NIR showed higher degrees of conversion of the acrylate groups as compared to the control, however, the oxirane groups did not convert very well indicating some possible steric hindrance due to the much quicker acrylate cure.
Conclusions: A novel hybrid oxirane-acrylate monomer blend was synthesized and resins with different oxirane and acrylate content were made. These resins are more hydrophobic than those of the bis-GMA/TEGDMA control, and thus likely more resistant to hydrolysis. However, increase in oxirane content also decreased hardness and degree of cure. Further adjustments in initiator system and assessment of mechanical properties, shrinkage stress, volumetric shrinkage and degradation properties are currently being assessed.
Methods: A novel monomer blend containing 25% urethane diacrylate (UDA), 25% urethane dioxirane, and 50% hybrid urethane acrylate oxirane (UAO) was synthesized. Resins made with this blend contain 50% acrylate and 50% oxirane groups. Resins were also made with varying concentrations of this blend and UDA or p-cycloaliphatic diepoxide (Epalloy-5000) to form resins with 25% acrylate:75% oxirane, and 75% acrylate:25% oxirane. Resins were also made with Epalloy (100% oxirane) or 100% UDA alone. Control was 70:30 Bis-GMA:TEGDMA resin. A novel 2-component initiator system capable of free radical and cationic initiation containing 4-Isopropyl-4'-methyldiphenyliodonium tetrakis borate and camphorquinone was optimized together with an oligomeric diol (polytetrahydrofuran) for these monomer blends. Resins were light-cured and tested for degree of cure (Durometer-D hardness), hydrophobicity (contact angle goniometry), and near-IR FTIR (NIR) degree of conversion.
Results: All experimental groups were significantly more hydrophobic than the control. Interestingly, the 25% oxirane group was most hydrophobic. However, hardness decreased as oxirane content increased, but the 25% oxirane group had comparable hardness to the control. NIR showed higher degrees of conversion of the acrylate groups as compared to the control, however, the oxirane groups did not convert very well indicating some possible steric hindrance due to the much quicker acrylate cure.
Conclusions: A novel hybrid oxirane-acrylate monomer blend was synthesized and resins with different oxirane and acrylate content were made. These resins are more hydrophobic than those of the bis-GMA/TEGDMA control, and thus likely more resistant to hydrolysis. However, increase in oxirane content also decreased hardness and degree of cure. Further adjustments in initiator system and assessment of mechanical properties, shrinkage stress, volumetric shrinkage and degradation properties are currently being assessed.