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The objective of this study was to characterize the chemical and physical properties of bioactive ceramics prepared from an aqueous paste containing hydroxyapatite (HA) and beta tri-calcium phosphate (β-TCP). Prior to formulating the paste, HA and β-TCP were calcined at 800 ℃ and 975 ℃ (11 h), milled, and blended into 15%/85% HA/β-TCP volume-mixed paste. Fabricated cylindrical rods were subsequently sintered to 900 ℃, 1100 ℃ or 1250 ℃. The sintered specimens were characterized by helium pycnometry, X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), and inductively coupled plasma (ICP) spectroscopy for evaluation of porosity, crystalline phase, functional-groups, and Ca:P ratio, respectively. Mechanical properties were assessed via 3-point bending and diametral compression. Qualitative microstructural evaluation using scanning electron microscopy (SEM) showed larger pores and a broader pore size distribution (PSD) for materials sintered at 900 ℃ and 1100 ℃, whereas the 1250 ℃ samples showed more uniform PSD. Porosity quantification showed significantly higher porosity for materials sintered to 900 ℃ and 1250 ℃ (p < 0.05). XRD indicated substantial deviations from the 15%/85% HA/β-TCP formulation following sintering where lower amounts of HA were observed when sintering temperature was increased. Mechanical testing demonstrated significant differences between calcination temperatures and different sintering regimes (p < 0.05). Variation in chemical composition and mechanical properties of bioactive ceramics were direct consequences of calcination and sintering.


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Sintering effects on chemical and physical properties of bioactive ceramics

Show Author's information Lukasz WITEKa,b,*( )James SMAYaNelson R. F. A. SILVAcTeja GUDAdJoo L. ONGdPaulo G. COELHOb,e
School of Chemical Engineering, Oklahoma State University, 423 Engineering North, Stillwater, OK, USA
Department of Operative Dentistry, Universidade Federal de Minas Gerais, Pampulha, Belo Horizonte, MG, Brazil
Department of Biomedical Engineering, University of Texas San Antonio, One UTSA Circle, San Antonio, TX, USA
Department of Biomaterials and Biomimetics, New York University, 345 East 24th Street, 804S New York, NY, USA
Department of Periodontology and Implant Dentistry, College of Dentistry, New York University, 345 East 24th Street, New York, NY, USA

Abstract

The objective of this study was to characterize the chemical and physical properties of bioactive ceramics prepared from an aqueous paste containing hydroxyapatite (HA) and beta tri-calcium phosphate (β-TCP). Prior to formulating the paste, HA and β-TCP were calcined at 800 ℃ and 975 ℃ (11 h), milled, and blended into 15%/85% HA/β-TCP volume-mixed paste. Fabricated cylindrical rods were subsequently sintered to 900 ℃, 1100 ℃ or 1250 ℃. The sintered specimens were characterized by helium pycnometry, X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), and inductively coupled plasma (ICP) spectroscopy for evaluation of porosity, crystalline phase, functional-groups, and Ca:P ratio, respectively. Mechanical properties were assessed via 3-point bending and diametral compression. Qualitative microstructural evaluation using scanning electron microscopy (SEM) showed larger pores and a broader pore size distribution (PSD) for materials sintered at 900 ℃ and 1100 ℃, whereas the 1250 ℃ samples showed more uniform PSD. Porosity quantification showed significantly higher porosity for materials sintered to 900 ℃ and 1250 ℃ (p < 0.05). XRD indicated substantial deviations from the 15%/85% HA/β-TCP formulation following sintering where lower amounts of HA were observed when sintering temperature was increased. Mechanical testing demonstrated significant differences between calcination temperatures and different sintering regimes (p < 0.05). Variation in chemical composition and mechanical properties of bioactive ceramics were direct consequences of calcination and sintering.

Keywords:

bone graft material, chemical/physical characterization, sintering, bi-phasic calcium phosphate (BCP)
Received: 01 March 2013 Revised: 16 May 2013 Accepted: 13 June 2013 Published: 07 September 2013 Issue date: September 2013
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Publication history

Received: 01 March 2013
Revised: 16 May 2013
Accepted: 13 June 2013
Published: 07 September 2013
Issue date: September 2013

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© The author(s) 2013

Acknowledgements

Professor Van Thompson from King's College London Dental Institute (https://kclpure.kcl.ac.uk/portal/van. thompson.html) is gratefully acknowledged for his guidance as well as for putting this group of authors together to complete this work and manuscript.

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