Modification of Electrochemically Deposited Apatite Using Supercritical Water and its Dental Application

采用超临界水作为电化学沉积磷灰石在纯钛上的改性方法。采用水热电化学方法将磷灰石涂覆在商业纯钛板上。在含有钙离子和磷酸盐离子的电解质中，以12.5 mA/cm^2的恒定直流电在25、60、100、150和200℃下加载1小时。将沉积在钛基体上的磷灰石在45 MPa、450℃的超临界水中保存8 h。经此处理后，磷灰石的结晶度提高，沉积磷灰石的锋利边缘被磨圆，钛基体与沉积磷灰石的结合强度显著提高。另一方面，在0.01 N HC1环境下的体重下降，模拟体液中的体重增加率也下降。结果表明，超临界水改性提高了沉积磷灰石的机械强度，但降低了其生物活性。将喷砂后的纯钛和12% AuPdAg合金板在450℃、45MPa的高压蒸釜中进行超临界水处理。场发射型扫描电镜观察结果表明，在空气中600℃加热后，SCW在cpTi表面形成了小于0.2μm的细颗粒，表面形成了厚层。x射线衍射分析表明，两种处理均在cpTi表面形成TiO_2。测定了两种贴面树脂经过和不经过上述处理后与金属板的结合强度。cpTi与SCW的结合强度均大于其他条件（p<0.05）。

Supercritical water was used as a modification method of electrochemically deposited apatite on pure titanium. The apatites were coated on a commercially pure titanium plate using a hydrothermal-electrochemical method. A constant direct current at 12.5 mA/cm^2 was loaded for 1 hr at 25, 60, 100, 150 and 200℃ in an electrolyte containing calcium and phosphate ions. The deposited apatite on the titanium substrate was stored in supercritical water at 450℃ under 45 MPa for 8 hr. With this treatment, the crystallinity of the apatites increased, sharp edges of the deposited apatites were rounded off, and the bonding strength of the titanium substrate to the deposited apatites significantly increased. On the other hand, weight loss in 0.01 N HC1 decreased and the weight gain rate in a simulated body fluid also decreased with this treatment. It is suggested that the modification using supercritical water improved the mechanical strength of the deposited apatite, but worsened its bioactivity.Furthermore, pure titanium and 12 % AuPdAg alloy plates after sandblasting were treated with super critical water )SCW) in an autoclave under 45MPa at 450℃. Field emission-type scanning electron microscopy showed that fine particles, less than 0.2μm, were formed on the cpTi with SCW and thick layer was formed on the surface heated at 600℃ in air. X-ray diffractometric study revealed that TiO_2 was formed on the cpTi with both the treatments. The bonding strength of two types of veneering resin to both metal plates with and without the above treatments were determined. The bonding strengths of cpTi with SCW to the one resin were larger than the other conditions )p<0.05).