Synthesis and in-vitro Analysis of Bioactive Dental Filler Particles

Objective: Zirconia and Silicon nitride based ceramics are promising candidates for dental fillers due to their suitable mechanical strength and relatively high fracture toughness. However, these inert materials have limited application where the formation of chemical bonds between the material and tissue are not essential. A way to broaden the dental application of these ceramics is promoting their bioactivity by means of ceramic-bioceramic solution. Methods: Calcium-phosphorous precursors were mixed with continuous agitation followed by exposure to microwaves at 1000W for 3min using CTAB as surfactant. Zirconia and silicon nitride as reinforcement were added to calcium precursor with increasing proportions. As-precipitated powders were heat treated at 400°C,600°C,800°C, and 1000°C. All samples were analyzed by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Mechanical properties were evaluated by compression testing. The ceramic-bioceramic composites have also been investigated in Phosphate Buffer Solution to evaluate its dissolution behaviour. RESULTS: FTIR and XRD confirmed the formation of required high strength ceramic reinforced apatite particles. SEM revealed that the particle size was in the range of 450-500nm. Mechanical testing results proved the enhanced compressive strength of zirconia and silicon nitride reinforced apatites as compared to native particles. The dissolution study showed more weight loss and structural changes for particles heat treated at low temperature as compare to others. Conclusion: High strength ceramic reinforced apatites with improved mechanical strength has a potential to be used as dental filler with better stability, bioactivity and tailored resorption rate according to clinical need.