Synthesis and characterization of wollastonite glass-ceramics for dental implant applications

Objectives. To synthesize a glass-ceramic (GC) that is suitable for non-metallic one-piece dental implant application. Methods. Three glasses in a SiO2-Al2O3-CaO-CaF2-K2O-B2O3-P2O5-CeO2-Y2O3 system were produced by wet chemistry. Differential thermal analysis (DTA) was carried out to determine the glass crystallization kinetic parameters and the heating schedules that were used for sintering of GCs. Crystalline phases and crystal morphologies were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Mechanical properties of the GCs were determined by ultrasonic and indentation tests and its machinability were evaluated. Chemical durability was carried out according to ISO 6872, whereas testing chemical degradation in tris buffered solution was executed according to ISO 10993-14. Results. XRD of the GC specimens showed that wollastonite was the main crystalline with other secondary phases; GC2 had cristobalite as an additional phase. SEM of the GCs revealed dense acicular interlocking crystals. Young's modulus of elasticity (E), true hardness (H-o) and fracture toughness (K-IC) of the GCs were 89-100 GPa, 4.85-5.17 GPa and 4.62-5.58 MPa m(0.5), respectively. All GCs were demonstrated excellent machinability. The GCs exhibited various chemical durability and degradation rates. K-1C values of the GCs following chemical durability testing were not significantly different from those of the original materials (p > 0.05). GC2 exhibited significantly higher K-1C value compared with GC1 and GC3 (p < 0.05) and its chemical durability satisfied ISO 6872 specification for dental ceramics. Significance. Wollastonite-cristobalite GC can be considered as a promising material for one-piece dental implant applications due to its strength, machinability and chemical durability. (C) 2014 Published by Elsevier Ltd on behalf of Academy of Dental Materials. All rights reserved.