Development of bioresorbable sintered apatites

用热分析、X射线衍射和红外光谱研究了在100 ℃和pH 9.0条件下烧结3天的碳酸磷灰石的烧结过程。的烧结温度，在该温度下的线性热收缩的等静压压缩标本急剧增加，减少的量成比例的碳酸盐最初存在于磷灰石。例如，具有超过8wt%碳酸盐的样品可以在比烧结不具有碳酸盐的样品所需的温度低近400 ° C的温度（650 ° C）下烧结。在烧结结束时的碳酸盐损失量，估计化学和红外光谱，大约等于样品重量损失估计热重。在pH为5.0的10 mM/L醋酸溶液中，在37 ℃下研究了烧结碳酸磷灰石的溶解行为，并与烧结羟基磷灰石和骨磷灰石进行了比较，以建立磷灰石生物材料体外物理化学溶解与其体内破骨细胞吸收能力之间的相似性。烧结的碳酸盐磷灰石和骨磷灰石都溶解到可感知的程度。它们的溶液组成以几乎相同的方式变化，直到接近反应结束。在过饱和度方面，30秒时烧结的碳酸磷灰石的溶液组合物与3.8天时烧结的羟基磷灰石的溶液组合物相当，这表明前一种样品比后一种样品更易溶解。破骨细胞，这是从1日龄的新生兔的长骨，吸收骨和烧结的碳酸磷灰石，但他们没有再吸收烧结的羟基磷灰石。这些研究结果表明，烧结碳酸磷灰石，这具有的特点，可以有利地与骨相比，特别是在其反应性的酸性介质，将是有用的生物可吸收骨替代品。

Sintering of carbonate apatite, prepared at 100ﾟC and pH 9.0 for 3 days, was studied by therma analysis, x-ray diffraction and infrared spectroscopy. The sintering temperature, at which the linear thermal shrinkage of isostatically compacted specimens increased sharply, decreased in proportion to the amount of carbonate initially present in the apatite. For example, specimens with over 8 wt% carbonate could be sintered at a temperature (650ﾟC) which was nearly 400ﾟC lower than that needed for sintering a specimen with no carbonate. Amounts of carbonate lost at the end of sintering, estimated chemically and by infrared specroscopy, were approximately equal to sample weight losses estimatd thermogravimetrically. Dissolution behavior of sintered carbonate apatite was also investigated in a 10mM/L acetic acid solution adjusted to pH 5.0 at 37ﾟC and compared to that of sintered hydroxyapatite and bone apatite for the purpose of establishing some similarities between pysicochemical dissolution of apatite biomaterials in vitro and their ability to be resorbed by osteoclasts in vivo. Both the sintered carbonate apatite and the bone apatite dissolved to an appreciable extent. Their solution compositions changed in an almost identical manner until toward the end of the reaction. The solution compositions for sintered carbonate apatite at 30 seconds was comparable with that for sintered hydroxyapatite at 3.8 days with respect to the degree of supersaturation, indicating that the former specimen is much more soluble than the latter specimen. Osteoclasts, which were obtained from the long bones of 1-day-old neonatal rabbits, resorbed bone and sintered carbonate apatite, but they did not resorb sintered hydroxyapatite. These findings suggest that sintered carbonate apatites, which have characteristics that can be favorably compared with those of bone, especially with respect to its reactivity to acid media, would be useful as bioresorbable bone substitutes.