Used to have fuchsin, but now a dye in propylene glycol. Outer carious dentin stainable by solution because it has collagen fiber loosened by irreversible breakdown of intermolecular crosslinks. Thus, it allows penetration of propylene glycol.
Resin-dentin bond via dentin adhesives deteriorate over time.
1) Cleanse carious lesion with water and dry with air (water will contaminate solution)
2) One drop applied to lesion for TEN seconds
3) High speed held close and rinse with water
4) When color not seen anymore, spray-wash with syringe and then air-dry
5) After Removal of Caries: use 0.2% CHX in order to reduce MMP