Compositions and methods for forming, in an aqueous environment, a nanoaggregate of calcium fluoride and amorphous calcium phosphate-containing compound, such as amorphous calcium phosphate fluoride or amorphous calcium carbonate phosphate fluoride are described. The nanoaggregate (or nanocomposite) can release calcium, phosphate, and fluoride, and ultimately convert to the tooth mineral, fluorapatite. One method for forming such a nanoaggregate involves applying a non-aqueous (e.g., varnish-based) composition (e.g., a suspension), containing solid particles of water soluble salts of calcium, phosphate, and fluoride, to the aqueous environment of the mouth. This results in rapid solubilization of the salts, precipitation of the nanoaggregate, and tooth remineralization. Tooth fluoridation and remineralization may also be carried out by applying to the tooth a non-aqueous carrier containing the nanoaggregate. Whitening agents can also be added to these compositions and methods.