In vivo stains are the prompt resources, which have emerged in recent years so as to aid as clinical diagnostic tools in detecting early potentially malignant and malignant lesions. Toluidine blue by its property of retaining in the increased DNA and RNA cellular activity areas, aids in delineating the suspicious areas. However, it is hazardous if swallowed, and was shown to have toxicity to fibroblasts. Methylene blue has a similar chemical structure and exhibits similar physicochemical properties to toluidine blue. It is less toxic to the human body and has recently been proposed for...