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Influence of processing parameters on microstructure and biocompatibility of surface laser sintered hydroxyapatite–SiO 2 composites
Author(s) -
Kivitz E.,
Görke R.,
Schilling A. F.,
Zhang J.,
Heinrich J. G.
Publication year - 2013
Publication title -
journal of biomedical materials research part b: applied biomaterials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 108
eISSN - 1552-4981
pISSN - 1552-4973
DOI - 10.1002/jbm.b.32858
Subject(s) - materials science , sintering , biocompatibility , microstructure , amorphous solid , composite material , cristobalite , differential scanning calorimetry , scanning electron microscope , thermal expansion , phase (matter) , selective laser sintering , ceramic , quartz , metallurgy , crystallography , chemistry , physics , organic chemistry , thermodynamics
Silica‐doped hydroxyapatite (HA) is a promising material concerning biocompatibility to natural bone, bioactivity and osteoconductive characteristics. HA exhibits phase transformations during sintering which are attendant to the change in volume and thermal strain. To avoid cracks during sintering, the exact knowledge of the phase transition temperatures is necessary. The sintering behavior of HA can be improved by adding amorphous silica with a low coefficient of thermal expansion. Therefore, the phase transformations in the system HA–SiO 2 were analyzed by using differential scanning calorimetry followed by quantitative phase analysis by X‐ray diffraction with the Riedveld method. The maximum sintering temperature without reversible phase transformation was defined as 1265°C. In laser surface sintered (LSS) samples, amorphous SiO 2 , HA, and Si‐α‐TCP (or α‐TCP) were detected. By comparison, only crystalline phases, such as cristobalite, HA, β‐TCP, and Si‐α‐TCP (or α‐TCP), were determined after furnace sintering. Scanning electron microscopy micrographs of furnace sintered and LSS samples show the differences in the resulting microstructures. Biocompatibility was determined by measuring cell activity of osteoblasts cultivated on four laser‐sintered materials in the HA–SiO 2 system in comparison to normal cell culture plastic. Cell proliferation was similar on all surfaces. The level of the cell activity on day 8 varied depending on the composition of the material and increased linearly as the amorphous SiO 2 content rose. Taken together a laser‐based method to develop novel biocompatible HA–SiO 2 ceramics with adjustable properties and possible applications as orthopedic bioceramics are discussed. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.