Takagi S, Chow L C, Ishikawa K
American Dental Association Health Foundation, Paffenbarger Research Center, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA>
Biomaterials. 1998 Sep;19(17):1593-9. doi: 10.1016/s0142-9612(97)00119-1.
Tetracalcium phosphate (TTCP) has been shown previously to be an essential component of self-setting calcium phosphate cements that form hydroxyapatite (HA) as the only end-product. We report herein on a new self-setting calcium phosphate cement that does not contain TTCP. These cements consist of dicalcium phosphate anhydrous (DCPA), dicalcium phosphate dihydrate (DCPD), alpha-tricalcium phosphate, or amorphous calcium phosphate and, as an additional source of calcium, calcium hydroxide or calcium carbonate. These cements require the use of a phosphate (0.2 moll(-1) or higher) solution or a high pH solution as the cement liquid. The cements harden in relatively short time (5-30 min) and form HA as the dominant end-product in 24 h. The diametral tensile strengths of the 24-h samples are in the range of 0.2 to 7.5 MPa. Results from X-ray diffraction studies suggest that the cement setting is caused by rapid HA formation induced by the high phosphate concentration of the cement liquid. Because DCPA and DCPD are highly soluble at pH values above 12.7, which is the pK3 of phosphoric acid, high phosphate concentration in the slurry solution was also attainable by using a highly alkaline solution as the cement liquid. The physicochemical properties of these cements are comparable to those of TTCP-containing cements, and the new cements may be expected to have in vivo characteristics similar to those of TTCP-containing cements as well.
磷酸四钙（TTCP）先前已被证明是自固化磷酸钙骨水泥的重要组成部分，该骨水泥仅以羟基磷灰石（HA）作为最终产物。我们在此报告一种不含TTCP的新型自固化磷酸钙骨水泥。这些骨水泥由无水磷酸二钙（DCPA）、二水磷酸二钙（DCPD）、α-磷酸三钙或无定形磷酸钙组成，作为额外的钙源，还含有氢氧化钙或碳酸钙。这些骨水泥需要使用磷酸盐（0.2 moll(-1)或更高）溶液或高pH值溶液作为骨水泥液体。这些骨水泥在相对较短的时间内（5 - 30分钟）硬化，并在24小时内形成HA作为主要的最终产物。24小时样品的径向拉伸强度在0.2至7.5 MPa范围内。X射线衍射研究结果表明，骨水泥的凝固是由骨水泥液体中高磷酸盐浓度诱导的HA快速形成引起的。由于DCPA和DCPD在高于12.7的pH值下高度可溶，而12.7是磷酸的pK3，因此通过使用高碱性溶液作为骨水泥液体，也可在浆液中获得高磷酸盐浓度。这些骨水泥的物理化学性质与含TTCP的骨水泥相当，预计新型骨水泥在体内的特性也与含TTCP的骨水泥相似。
