A D'Onofrio1, N W Kent2, S A Shahdad3, R G Hill4. 1. Dental Physical Sciences Unit, Institute of Dentistry, Queen Mary University of London, Bancroft Road, London E1 4NS, United Kingdom. Electronic address: alessia.donofrio@qmul.ac.uk. 2. Dental Physical Sciences Unit, Institute of Dentistry, Queen Mary University of London, Bancroft Road, London E1 4NS, United Kingdom. Electronic address: n.kent@ucl.ac.uk. 3. Restorative Dentistry, The Royal London Dental Hospital, Turner Street, London E1 1BB, United Kingdom. Electronic address: shakeel.shahdad@bartshealth.nhs.uk. 4. Dental Physical Sciences Unit, Institute of Dentistry, Queen Mary University of London, Bancroft Road, London E1 4NS, United Kingdom. Electronic address: r.hill@qmul.ac.uk.
Abstract
OBJECTIVE: The aim of this study was to investigate the effect on properties of increasing strontium substitution for calcium in bioactive glasses used as precursors for novel calcium phosphate cements. METHODS: Glasses were produced by progressively substituting strontium for calcium. Cements were prepared by mixing the glass powder with Ca(H2PO4)2 powder with a 2.5% solution of Na2HPO4. Setting times and compressive strength were measured after 1h, 1 day, 7 days and 28 days immersion in Tris buffer solution. X-ray diffraction (XRD), Fourier transform infrared spectroscopy and radiopacity were measured and crystal morphology was assessed using scanning electron microscopy. RESULTS: A correlation between the phases formed, morphology of the crystallites, setting time and compressive strength were analyzed. Setting time increased proportionally with strontium substitution in the glass up to 25%, whereas for higher substitutions it decreased. Compressive strength showed a maximum value of 12.5MPa and was strongly influenced by the interlocking of the crystals and their morphology. XRD showed that the presence of strontium influenced the crystal phases formed. Octacalcium phosphate (Ca8H2(PO4)6·5H2O, OCP) was the main phase present after 1h and 1 day whereas after 28 days OCP was completely transformed to strontium-containing hydroxyapatite (SrxCa(10-x)(PO4)6(OH)2, SrHA). Radiopacity increased proportionally to strontium substitution in the glass. SIGNIFICANCE: A novel method to develop a bone substitute forming in vitro SrHA as a final product by using a bioactive glass as a precursor was shown. These novel injectable bioactive glass cements are promising materials for dental and orthopedic applications. Further in vivo characterizations are being conducted.
OBJECTIVE: The aim of this study was to investigate the effect on properties of increasing strontium substitution for calcium in bioactive glasses used as precursors for novel calcium phosphate cements. METHODS: Glasses were produced by progressively substituting strontium for calcium. Cements were prepared by mixing the glass powder with Ca(H2PO4)2 powder with a 2.5% solution of Na2HPO4. Setting times and compressive strength were measured after 1h, 1 day, 7 days and 28 days immersion in Tris buffer solution. X-ray diffraction (XRD), Fourier transform infrared spectroscopy and radiopacity were measured and crystal morphology was assessed using scanning electron microscopy. RESULTS: A correlation between the phases formed, morphology of the crystallites, setting time and compressive strength were analyzed. Setting time increased proportionally with strontium substitution in the glass up to 25%, whereas for higher substitutions it decreased. Compressive strength showed a maximum value of 12.5MPa and was strongly influenced by the interlocking of the crystals and their morphology. XRD showed that the presence of strontium influenced the crystal phases formed. Octacalcium phosphate (Ca8H2(PO4)6·5H2O, OCP) was the main phase present after 1h and 1 day whereas after 28 days OCP was completely transformed to strontium-containing hydroxyapatite (SrxCa(10-x)(PO4)6(OH)2, SrHA). Radiopacity increased proportionally to strontium substitution in the glass. SIGNIFICANCE: A novel method to develop a bone substitute forming in vitro SrHA as a final product by using a bioactive glass as a precursor was shown. These novel injectable bioactive glass cements are promising materials for dental and orthopedic applications. Further in vivo characterizations are being conducted.
Authors: R Jayasree; T S Sampath Kumar; S Mahalaxmi; Sireesha Abburi; Y Rubaiya; Mukesh Doble Journal: J Mater Sci Mater Med Date: 2017-05-13 Impact factor: 3.896
Authors: Hockin Hk Xu; Ping Wang; Lin Wang; Chongyun Bao; Qianming Chen; Michael D Weir; Laurence C Chow; Liang Zhao; Xuedong Zhou; Mark A Reynolds Journal: Bone Res Date: 2017-12-20 Impact factor: 13.567