The invention relates to the use of sphingosine-based compounds, in particular phytosphingosine compounds, in the protection of hydroxyapatite containing materials such as teeth and bone. Such compounds are especially useful in the treatment and prevention of dental caries, dental erosion, dentine hypersensitivity and tartar (dental calculus) formation. Methods and devices are also provided for preventing biofilm formation using sphingosine-based compounds. Compositions comprising sphingosine-based compounds are also provided.