Development of self-setting calcium hydroxide preparation using dicalcium phosphate anhydrous and sodium hydrogen phosphate aqueous solution

Although a calcium hydroxide preparation is widely used in dental clinics as a base liner and a root canal filling material, its very high basicity causes necrosis of the dental pulp and it does not set. In this study, we evaluated the feasibility of developing a calcium hydroxide preparation that has a good setting ability and a moderate basicity. The calcium hydroxide preparation examined showed a good setting ability and formed an apatitic mineral upon setting when dicalcium phosphate anhydrous (DCPA) powder was added and mixed with sodium hydrogen phosphate aqueous solution. Setting mechanism had a close relationship with apatite formation. As a result of the addition of DCPA, that is, acidic calcium phosphate, the calcium hydroxide preparation showed a relatively mild basicity when compared with the DCPA-free calcium hydroxide preparation. An animal study demonstrated that a calcium hydroxide preparation containing DCPA causes less inflammatory response at the initial stage and elicits faster secondary dentin formation than DCPA-free calcium hydroxide preparation. We concluded therefore that a calcium hydroxide preparation containing DCPA is a promising alternative to the calcium hydroxide preparation currently used in dental clinics.