Grover L M, Knowles J C, Fleming G J P, Barralet J E
Biomaterials Unit, Birmingham Dental School, University of Birmingham, St Chad's Queensway, B4 6NN, Birmingham, UK.
Biomaterials. 2003 Oct;24(23):4133-41. doi: 10.1016/s0142-9612(03)00293-x.
In vivo studies investigating the use of brushite cements have demonstrated mixed results with one or more of dissolution, hydrolysis, fragmentation and long term stability being demonstrated. It has been suggested that sample volume, implant location, and species can affect in vivo behaviour. As few in vitro studies on this cement system have been performed, this study aimed to compare the effects of static and dynamic in vitro ageing protocols on the phase composition, weight loss and mechanical properties of brushite cement. The effects of immersion liquid to cement volume ratio (LCVR) and sample volume on phase composition were investigated and comparative in vitro experiments were also performed in foetal bovine serum. It was determined that the weight loss after 28 days was up to seven times higher in serum than in phosphate buffered saline (PBS) and that fragmentation accounted for most of the weight loss observed. Hydroxyapatite was formed in PBS but not in serum when aged in refreshed media at all LCVRs investigated. This study has highlighted that LCVR, media refresh rate and media composition are critical to brushite cement performance. It appears that brushite cement removal from an implant site may be complex and dependent on physiological processes other than simple dissolution. A better understanding of these processes could provide the means to engineer more precise calcium phosphate cement degradation profiles.
研究透钙磷石骨水泥应用的体内研究结果不一，出现了溶解、水解、破碎和长期稳定性等一种或多种情况。有人提出，样本体积、植入位置和物种会影响体内行为。由于针对该骨水泥系统的体外研究较少，本研究旨在比较静态和动态体外老化方案对透钙磷石骨水泥相组成、重量损失和力学性能的影响。研究了浸泡液与骨水泥体积比（LCVR）和样本体积对相组成的影响，并在胎牛血清中进行了对比体外实验。结果表明，28天后血清中的重量损失比磷酸盐缓冲盐水（PBS）中高出多达7倍，且观察到的重量损失大部分是由破碎造成的。在所有研究的LCVR下，于新鲜培养基中老化时，PBS中形成了羟基磷灰石，而血清中未形成。本研究强调，LCVR、培养基更新率和培养基组成对透钙磷石骨水泥性能至关重要。透钙磷石骨水泥从植入部位的移除似乎可能很复杂，且取决于简单溶解以外的生理过程。对这些过程的更好理解可为设计更精确的磷酸钙骨水泥降解曲线提供方法。
