title: Self-Strengthening Hybrid Dental Adhesive via Visible-light Irradiation Triple Polymerization.
abstract: A self-strengthening methacrylate-based dental adhesive system was developed by introducing an epoxy cyclohexyl trimethoxysilane (TS) which contains both epoxy and methoxysilyl functional groups. The experimental formulation, HEMA/BisGMA/TS (22.5/27.5/50, wt%), was polymerized by visible-light. Real-time Fourier transform infrared spectroscopy (FTIR) was used to investigate in situ the free radical polymerization of methacrylate, ring-opening cationic polymerization of epoxy, and photoacid-induced sol-gel reactions. Among the three simultaneous reactions, the reaction rate of the free radical polymerization was the highest and the hydrolysis/condensation rate was the lowest. With 40s-irradiation, the degrees of conversion of the double bond and epoxy groups at 600 s were 73.2±1.2%, 87.9±2.4%, respectively. Hydrolysis of the methoxysilyl group was initially <5%, and increased gradually to about 50% after 48 h dark storage. Photoacids generated through the visible-light-induced reaction were effective in catalyzing both epoxy ring-opening polymerization and methoxysilyl sol-gel reaction. The mechanical properties of copolymers made with TS concentrations from 5 to 35 wt% were obtained using dynamic mechanical analysis (DMA). In wet conditions, the storage moduli at 70 °C and glass transition temperature were significantly higher than that of the control (p<0.05); these properties increased with TS concentration and storage time. The post reaction of hydrolysis/condensation of alkoxysilane could provide persistent strengthening whether in a neutral or acidic environment and these characteristics could lead to enhanced mechanical properties in the oral environment. The cumulative amount of leached species decreased significantly in the TS-containing copolymers. These results provide valuable information for the development of dental adhesives with reduced leaching of methacrylate monomers and enhanced mechanical properties under the wet, oral environment.
authors: University of Kansas, Bioengineering Research Center, 1530 W. 15th Street, Lawrence, KS 66045-7609, USA.
authors: Linyong
authors: L
authors: Song
authors: University of Kansas, Bioengineering Research Center, 1530 W. 15th Street, Lawrence, KS 66045-7609, USA.
authors: Qiang
authors: Q
authors: Ye
authors: University of Kansas, Bioengineering Research Center, 1530 W. 15th Street, Lawrence, KS 66045-7609, USA.
authors: Xueping
authors: X
authors: Ge
authors: University of Kansas, Bioengineering Research Center, 1530 W. 15th Street, Lawrence, KS 66045-7609, USA.; University of Kansas, Department of Civil Engineering, 1530 W. 15th Street, Lawrence, KS 66045-7609, USA.
authors: Anil
authors: A
authors: Misra
authors: University of Kansas, Bioengineering Research Center, 1530 W. 15th Street, Lawrence, KS 66045-7609, USA.; University of Kansas, Department of Mechanical Engineering, 1530 W. 15th Street, Lawrence, KS 66045-7609, USA.
authors: Candan
authors: C
authors: Tamerler
authors: University of Kansas, Bioengineering Research Center, 1530 W. 15th Street, Lawrence, KS 66045-7609, USA.; University of Kansas, Department of Mechanical Engineering, 1530 W. 15th Street, Lawrence, KS 66045-7609, USA.
authors: Paulette
authors: P
authors: Spencer