Tobias T Tauböck1, Matthias Zehnder1, Thomas Schweizer2, Wendelin J Stark3, Thomas Attin1, Dirk Mohn4. 1. Department of Preventive Dentistry, Periodontology and Cariology, Center for Dental Medicine, University of Zurich, Zurich, Switzerland. 2. Institute of Polymers, Department of Materials, ETH Zurich, Zurich, Switzerland. 3. Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland. 4. Department of Preventive Dentistry, Periodontology and Cariology, Center for Dental Medicine, University of Zurich, Zurich, Switzerland; Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland. Electronic address: dirk.mohn@chem.ethz.ch.
Abstract
OBJECTIVES: To investigate chemo-mechanical effects of incorporating alkaline bioactive glass nanoparticles into a light-curable dental resin matrix. METHODS: An unfilled Bis-GMA/TEGDMA material was infiltrated with up to 20 wt% of ultrafine SiO2-Na2O-CaO-P2O5-Bi2O3 particles. The unfilled and filled resins were investigated regarding their viscosity before setting and compared to commercially available materials. Set specimens were immersed for 21 days in phosphate buffered saline at 37°C. Water uptake, pH, Knoop hardness, and degree of conversion of freshly polymerized and stored samples were investigated. Resin surfaces were viewed and mapped in a scanning electron microscope for the formation of calcium phosphate (Ca/P) precipitates. In addition, Raman spectroscopy was performed. Numeric values were statistically compared (p<0.01). RESULTS: Viscosity increased with particle loading, but remained below that of a flowable dental composite material. Water uptake into and pH induction from the polymerized samples also increased with particle loading (p<0.01). The addition of 20 wt% nanoparticles had no significant influence on microhardness, yet it slightly (p<0.01) increased the degree of conversion after 21 days. Ca/P precipitates formed on specimens filled with 20 wt% of the particles, while they were scarce on counterparts loaded with 10 wt%, and absent on unfilled resin surfaces. SIGNIFICANCE: The results of the current study show that a Bis-GMA-based resin can be functionalized using alkaline nanoparticles. A material with bioactive properties and similar hardness as the unfilled resin was obtained by incorporating 20wt% of ultrafine SiO2-Na2O-CaO-P2O5-Bi2O3 particles into the resin matrix.
OBJECTIVES: To investigate chemo-mechanical effects of incorporating alkaline bioactive glass nanoparticles into a light-curable dental resin matrix. METHODS: An unfilled Bis-GMA/TEGDMA material was infiltrated with up to 20 wt% of ultrafineSiO2-Na2O-CaO-P2O5-Bi2O3 particles. The unfilled and filled resins were investigated regarding their viscosity before setting and compared to commercially available materials. Set specimens were immersed for 21 days in phosphate buffered saline at 37°C. Water uptake, pH, Knoop hardness, and degree of conversion of freshly polymerized and stored samples were investigated. Resin surfaces were viewed and mapped in a scanning electron microscope for the formation of calcium phosphate (Ca/P) precipitates. In addition, Raman spectroscopy was performed. Numeric values were statistically compared (p<0.01). RESULTS: Viscosity increased with particle loading, but remained below that of a flowable dental composite material. Water uptake into and pH induction from the polymerized samples also increased with particle loading (p<0.01). The addition of 20 wt% nanoparticles had no significant influence on microhardness, yet it slightly (p<0.01) increased the degree of conversion after 21 days. Ca/P precipitates formed on specimens filled with 20 wt% of the particles, while they were scarce on counterparts loaded with 10 wt%, and absent on unfilled resin surfaces. SIGNIFICANCE: The results of the current study show that a Bis-GMA-based resin can be functionalized using alkaline nanoparticles. A material with bioactive properties and similar hardness as the unfilled resin was obtained by incorporating 20wt% of ultrafineSiO2-Na2O-CaO-P2O5-Bi2O3 particles into the resin matrix.