Fabrication of calcium phosphate composite polymer/SLS-stabilized emulsion-based bioactive gels and their application for dentine tubule occlusion

Objectives Calcium phosphate/SLS/P123 composite bioactive gels were prepared to achieve dentine tubule occlusion. Methods Gels containing calcium phosphate particles were prepared in a water-in-oil microemulsion system with a mixture of triblock copolymer pluronic (P123) as a co-surfactant and sodium lauryl sulfate (SLS) as a surfactant in cyclohexane. Subsequently, calcium chloride dihydrate and sodium hydrogen phosphate aqueous solutions were added in a water phase. Finally, slow evaporation of the oil phase at room temperature was performed to produce a hybrid gel. The obtained gels were investigated for their toxicity by the sulforhodamine B (SRB) assay and applied on human dentine specimens to examine their ability to occlude dentine tubules. Results The size and morphology of the calcium phosphate particles embedded in the gel depended on the concentration of P123 and SLS, which were used as a template for mineral precipitation. The prepared calcium phosphate particles (200–500 nm in diameter) with the maximum polymer and surfactant content exhibited spherical shapes. Further, on reducing their content twice and tenfold yields micro-particles with flower-like shapes. These bioactive gels were able to occlude into dentine tubules after 3 days of application with a plugging rate of 79.22% when using the smallest particles. In addition, calcium phosphate nanorods were transformed into dentine tubules with a maximum depth of 6 μm on increasing the amount of gel. Conclusions The bioactive gels were effectively used as bioactive fillers to occlude exposed human dentine tubules.