Bausch Intra Oral Ink = BIO lnk®green is also used to mark sore spots on the gum. BIO-lnk®is a highly viscous, aqueous solution containing green food dye. It can be applied directly to the oral mucosa using a cotton pellet. The sore spot on the gum is gently marked. After replacing the denture, a green contact mark can be detected on the lower side of the denture showing the area to be adjusted.