Development of organic acid-apatite based dental cement

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Although the exact ratio of Te-CP, β-TCP and NaィイD23ィエD2CaィイD26ィエD2(POィイD24ィエD2)ィイD25ィエD2 was not determined, pulverized samples of 1700゜C-CAP were found to set when mixed with certain organic acid solutions. With 30wt% malic acid, setting time increased as the P/L ratios decreased. Nevertheless, the setting time at P/L rations between 1.54 and 3.08 appeared to be in the range acceptable from clinical requirements. At a P/L ratio of 3.08, the setting time was found to be almost constant at 3 minutes in the malic acid concentration range of from 20 to 30 wt%. This finding may suggest that it is possible to develop a calcium phosphate cement that has less acid irritation without significantly changing the setting time, since less irritation would be expected at lower acid concentrations. With citric acid, however, the setting time increased as the concentration was lowered. The compressive strength of the cement developed in the present study was greater than 50MPa when 30wt% malic acid … More was used at a P/L ratio of 3.08. This strength, which is greater than the reported values for calcium phosphate cements developed so far, appears to be more than sufficient for application in non-stress bearing bone. As clearly demonstrated in HeLa-cell cultures, the cement mixed with malic acid was less cytotoxic than the cement used as a negative control. Since the acidity of our two calcium phosphate cements during and after setting was approximately the same, their cytotoxic difference may be related to the difference in the acids themselves, suggesting that malic acid solutions may be superior to citric acid solutions as the liquid phase in this regard. Similar findings were also obtained with osteoclasts. The culture experiments with these cells clearly suggested that the number of osteoclasts on the cement mixed with malic acid was significantly greater than that on the cement mixed in evaluating osteoclastic bioresobability of the cement, the above finding may suggest that the cement that is mixed with malic acid would be the more useful as a biocompatible dental cement. The finding obtained might expand the possibility of developing new calcium phosphate cements by use of commercially available chemicals alone. In marked contrast to calcium phosphate cements currently in use, which must be prepared by mechanically mixing at least two types of calcium phosphates that need to be prepared independently beforehand, no such mechanical mixing is needed for the calcium phosphate cements described in this study. Less