Dias A G, Gibson I R, Santos J D, Lopes M A
Instituto de Engenharia Biomédica (INEB), Laboratório de Biomateriais, Rua do Campo Alegre 823, 4150-180 Porto, Portugal.
Acta Biomater. 2007 Mar;3(2):263-9. doi: 10.1016/j.actbio.2006.09.009. Epub 2006 Dec 5.
The aim of this work was to evaluate the in vitro degradation behaviour of a 45CaO-37P(2)O(5)-5MgO-13TiO(2) (mol.%) glass ceramic, under two different simulated physiological conditions: normal physiological pH 7.4, and pH 3.0, which was designed to simulate the acidic conditions produced by osteoclast cells. The in vitro testing was carried out at 37 degrees C for up to 42 days for the pH 7.4 solution and for up to 1 day for the pH 3.0 solution. The incorporation of TiO(2) into the glass structure leads to the precipitation of specific crystalline phases in the glass matrix, namely alpha- and beta-Ca(2)P(2)O(7), TiP(2)O(7) and CaTi(4)(PO(4))(6). The degradation testing at pH 3.0 showed a higher weight loss compared with degradation testing at pH 7.4; the weight loss under the acidic condition after 1 day (24 h) was about 10 times higher than the weight loss after 42 days of immersion at pH 7.4. The ionic release profile of Ca(2+), PO(4)(3-), Mg(2+) and Ti(4+) showed a continuous increase in concentration over all immersion times for both testing solutions. After 1 day of immersion at pH 3.0, the concentration levels of Mg(2+), Ca(2+), PO(4)(3-) were about six times higher than the levels achieved after 42 days of immersion at pH 7.4. The glass ceramic showed similar degradation to hydroxyapatite, and therefore has potential to be used in certain clinical applications where relatively slow resorption of the implant and replacement by bone is required, e.g. cranioplasty.
本研究的目的是评估45CaO-37P₂O₅-5MgO-13TiO₂（摩尔%）玻璃陶瓷在两种不同模拟生理条件下的体外降解行为：正常生理pH值7.4和pH值3.0，后者旨在模拟破骨细胞产生的酸性条件。体外测试在37℃下进行，pH值7.4的溶液测试长达42天，pH值3.0的溶液测试长达1天。TiO₂掺入玻璃结构导致玻璃基体中特定晶相的沉淀，即α-和β-Ca₂P₂O₇、TiP₂O₇和CaTi₄(PO₄)₆。与pH值7.4的降解测试相比，pH值3.0的降解测试显示出更高的重量损失；酸性条件下1天（24小时）后的重量损失比在pH值7.4下浸泡42天后的重量损失高约10倍。Ca²⁺、PO₄³⁻、Mg²⁺和Ti⁴⁺的离子释放曲线显示，两种测试溶液在所有浸泡时间内浓度均持续增加。在pH值3.0下浸泡1天后，Mg²⁺、Ca²⁺、PO₄³⁻的浓度水平比在pH值7.4下浸泡42天后达到的水平高约六倍。该玻璃陶瓷显示出与羟基磷灰石相似的降解情况，因此有潜力用于某些需要植入物相对缓慢吸收并由骨替代的临床应用，例如颅骨成形术。
