Synthesis of bioactive and machinable miserite glass-ceramics for dental implant applications

摘要

Objectives. To synthesize and characterize machinable, bioactive glass-ceramics (GCs) suitable for dental implant applications. Methods. A glass in the SiO_2-Al_2O_3-CaO-CaF_2-K_2O-B_2C_3-La_2O_3 system was synthesized by wet chemical methods, followed by calcination, melting and quenching. Crystallization kinetics were determined by differential thermal analysis pTA). GC discs were produced by cold pressing of the glass powder and sintered using schedules determined by DTA. The crystalline phases and microstructure of GC samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Dynamic Young's modulus (E), true hardness (H_O), fracture toughness (K_(IC)) and brittleness index (BI) were evaluated. Bioactivity was studied by examining the formation of hydroxyapatite (HA) on the GC surfaces after soaking in simulated body fluid (SBF). Attachment and proliferation of MC3T3-E1 osteoblastic cells were assessed in uitro. Results. Miserite [KCa_5(Si_2O_7)(Si_6O_(15))(OH)F] was the main crystalline phase of the GC with additional secondary phases. Microstructural studies revealed interlocking lath-like crystalline morphology. E, H_O, and K_(IC) values for the GCs were 96±3 GPa, 5.27 ± 0.26 GPa and 4.77 ± 0.27 MPa m~(0.5), respectively. The BI was found to be 1.11 ± 0.05 μm~(-0.5), indicating outstanding machinability. An HA surface layer was formed on the GC surfaces when soaked in SBF, indicating potential bioactivity. MC3T3-E1 cells exhibited attachment, spreading and proliferation on GC surfaces, demonstrating excellent biocompatibility. Significance. We present a novel approach for the synthesis of miserite GC with the physical and biological properties required for non-metallic dental implant applications.