Disclosing solution is a simple but effective tool used in oral hygiene to help people visualize dental plaque, which is a sticky, colorless film of bacteria that constantly forms on the teeth. Plaque is difficult to see against the white surface of the enamel, making it challenging to know where brushing and flossing efforts are falling short. By temporarily staining this bacterial biofilm, the solution highlights areas that require more attention. This process makes the invisible visible, serving as a powerful educational aid for improving at-home cleaning techniques.
The Dye That Colors Plaque
The main ingredient in most disclosing solutions is a food-grade coloring agent, which acts as the stain to reveal the plaque. Historically, a common active component was Erythrosine (D&C Red No. 3 or Red No. 28), an organo-iodine compound that creates a bright red stain. Other formulations use different dyes, such as Fluorescein (D&C Yellow No. 8), which is detectable under a blue or ultraviolet light source.
These staining agents are selected because they are approved for oral use and are considered harmless. While the specific chemical makeup varies by manufacturer, the function remains the same: to provide a contrasting color. The presence of these dyes allows the bacterial film to stand out sharply against the clean tooth surface.
How the Solution Selectively Stains
The mechanism for selective staining relies on the chemical composition of the dental plaque itself. Dental plaque is a complex biofilm primarily made up of bacteria, proteins, and polysaccharides, which form a sticky, extracellular matrix. This matrix has a different chemical structure and surface charge compared to the smooth surface of the tooth enamel.
The dye molecules in the disclosing solution are attracted to and bind firmly with the components of this bacterial film, particularly the proteins and polysaccharides. This binding is often an electrostatic interaction, where the charged dye particles adhere to the charged components of the plaque. Clean enamel, lacking this sticky, porous matrix, does not retain the dye, allowing the solution to be rinsed away from the unstained areas. The result is a high-contrast visualization where only the areas covered in bacterial plaque are colored.
Single-Color Versus Dual-Color Systems
Disclosing solutions are categorized as single-color or multi-color systems. Single-color solutions use one dye to stain all plaque a uniform color, typically red or blue, regardless of how long it has been present. This provides a simple, direct map of all missed areas on the teeth.
Dual-color, or two-tone, systems use a combination of two different dyes to provide more detail about the plaque’s age. These formulas often use one color, such as red or pink, to stain newer plaque (less than 24 hours old). A second color, usually blue or purple, stains older plaque (more than 48 hours old). Older plaque has a denser biofilm structure that traps the second dye, while newer plaque only retains the first dye.
Steps for Using Disclosing Solutions
Disclosing agents are available as chewable tablets or as a liquid rinse. For tablets, the user chews the tablet thoroughly for about 30 seconds, mixing it with saliva, before swishing the mixture around the mouth to coat all tooth surfaces. For liquid solutions, a few drops or a small amount of the product is swished in the mouth for a similar duration.
Users must not swallow the solution or tablet, and should spit the excess into a sink. A light rinse with water can follow to remove loose dye, revealing the stained plaque on the teeth. The dye will temporarily color the gums, tongue, and lips, but this staining fades quickly. After identifying the stained areas, the final step is to brush and floss thoroughly to remove the highlighted plaque.