RESUMO
As an alternative to calcium hydroxide used as a direct capping agent, calcium phosphate cement that consisted of tetracalcium phosphate and alpha-tricalcium phosphate (Te-CP/alpha-TCP) at different molar ratios was developed with a one-step method, in which heating was performed only one time. Alkalinity could be adjusted easily by changing the Te-CP/alpha-TCP ratio, whereby the mixing ratio of simple chemicals such as calcium carbonate and dicalcium phosphate dihydrate was changed. When mixed with a solution of 1 mol/L sodium dihydrogen phosphate, the cement set forming carbonate-containing apatite in revised, simulated body fluid (R-SBF)--which served to mimic the tissue fluid in dental pulp. The pH of the solution never exceeded 8.0 in the presence of the set cement even after about one month of storage. In contrast, with calcium hydroxide, the pH of R-SBF reached almost 12.0 on day 1 and remained at that value till the end of immersion. These findings clearly suggested that with Te-CP/alpha-TCP cement, its alkalinity would never exceed that of calcium hydroxide and that it would provide a mildly alkaline environment.
