Effect of mesoporous silica@nano-bioactive glass complex particles on the durability of dentin bonding

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This study introduced a process for synthesizing mesoporous silicon@nano-bioactive glass (nano-BAG) complex particles, and evaluated their effects on dentin bonding and remineralizing activity. Mesoporous and nonporous silica microspheres were coated with nano-BAG via a quick alkali-mediated sol–gel method at different pH values (4, 7, 9). The eight groups of particles were examined by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, nitrogen adsorption tests, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Inductively coupled plasma optical emission spectrometry (ICP-OES) was employed to record the cumulative release of Ca2+ at 7, 14, and 28 days. The ability to promote the formation of hydroxyapatite was assessed by mineralization tests. The CCK-8 cell counting kit was used to test the cytotoxicity. Microtensile bond strength (μTBS) tests nanoleakage and were carried out to evaluate the effects of a pretreatment using mesoporous or nonporous silica microspheres coated with nano-BAG. XRD and FTIR analyses confirmed that nano-BAG coated mesoporous silica and formed a relatively ordered mesoporous structure, whereas nonporous silica did not exhibit major structural changes. In N2 adsorption tests, the specific surface area and pore volume of mesoporous silica (927.04 m2/g; 0.77 cm3/g) were much larger than those of silica (10.76 m2/g; 0.04 cm3/g). Both SEM and TEM revealed a greater homogeneity and dispersity in mesoporous silica coated with nano-BAG at pH 4. This kind of particles maintained a high level of cumulative release of Ca2+ (178.29 ± 0.950 mg/L at 28 days), showed the strongest Ca and P signal intensity after being immersed in SBF for 28 days, and exhibited higher μTBS values (41.56 ± 3.110 MPa) and minimal nanoleakage. Cytotoxicity tests indicated a well-preserved cell viability in these particles. Nano-BAG-coated mesoporous silica particles, obtained at pH 4, provided a stable release of Ca2+ in body fluid, and showed a strong ability to promote the formation of hydroxyapatite. These features are beneficial for enhancing the resin–dentin bonding and reducing nanoleakage.