| Title | In vitro degradation studies of calcium phosphate glass ceramics prepared by controlled crystallization |
| Publication Type | Journal Article |
| 2003 |
| Authors | Dias, AG, Lopes, MA, Gibson, IR, Santos, JD |
| Journal | Journal of Non-Crystalline SolidsJ Non Cryst Solids |
| Volume | 330 |
| Issue | 1-3 |
| Pagination | 81 - 89 |
| Date Published | 2003/// |
| 00223093 (ISSN) |
| Calcium Compounds, Crystallization, Degradation, Differential thermal analysis, Fourier transform infrared spectroscopy, Glass ceramics, Heat treatment, Nucleating agents, Nucleation, X ray diffraction |
| Calcium phosphate glass ceramics with incorporation of small additions of two nucleating agents, MgO and K 2O were prepared in the metaphosphate and pyrophosphate region, using an appropriate two-step heat treatment of controlled crystallization defined by differential thermal analysis results. Identification and quantification of crystalline phases precipitated from the calcium phosphate glass were performed using X-ray diffraction and Rietveld analysis. The β-Ca
2P
2O
7 (β-DCP), KCa(PO
3)
3, β-Ca(PO
3)
2 and Ca
4P
6O
19 phases were detected in the glass ceramics. In order to evaluate the degradation of the glass ceramics prepared, degradation studies were carried out during 42 days in Tris-HCl solution at 37 °C, pH 7.4, using granules in the range of 355-415 μm. The materials presented a weight loss ranging up to 12%. The ions leached during the immersion mainly originated from the KCa(PO
3)
3 phase, probably due to the presence of K
+ ion in the calcium metaphosphate, and the residual glassy phase. The structural changes at the surface of materials during degradation have been analyzed by Fourier transform infrared spectroscopy and X-ray diffraction. Results showed that significant surface changes occurred with immersion time, with the decrease of KCa(PO
3)
3, β-Ca
2P
2O
7 and β-Ca(PO
3)
2 phases occurring at different periods of immersion. This study has demonstrated an easy way to prepared calcium phosphate materials with specific calcium phosphate phases and crystallization, and therefore specific degradation rates. © 2003 Elsevier B.V. All rights reserved.
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