But when you drink <coffee>, it quickly washes around those bones and into your esophagus. It doesn't stick around. It's like getting a cross tattoo to become Jesus. coffee will be digested, and absorbed into your bloodstream, and cross your blood-brain barrier, for sure! But it won't stay adhering to your tooth-bones and the <yellowing> process never has a chance to start. That's absurd thinking that it somehow is internally effective. It's simply not the mechanism of action. There's not enough time for it to work. The process requires physical contact in order for a chemical reaction to occur!