Dental plaque disclosing agent

A composition in the form of an aqueous solution, for application to the oral cavity to accomplish the differential disclosure of dental plaque, said composition consisting essentially of FDC Red No. 3 and FDC Blue No. 1, said Blue No. 1 being present in an amount from about 0.1 to 4 parts by weight per each part by weight of FDC Red No. 3, said composition differentially staining areas of old, thick accumulations of dental plaque blue and thin, recent deposits of dental plaque red, whereby effectively practiced plaque removal on a given tooth shows, and can be photographed, as either no stain pickup or thin deposits staining red, while certain areas on said tooth if consistently missed, will be considerably thicker and therefore stained blue, and on some teeth, an intermediate definite purple zone can be distinguished between the red and blue areas, said intermediate definite purple area tending to look more like blue plaque than red plaque, but the thickness of this purple plaque being less than that of blue plaque, while tooth surfaces not covered with plaque do not show the dye at all.