I've suddenly noticed that one of my teeth has a chunk missing on the lower end (along the gumline). There is a lot of dentin exposed, and naturally it is sensitive to hot and cold, and painful if I touch it the wrong way. My dental appointment is on Tuesday. It is not painful to eat or anything, but are there things that I should be aware of and try to avoid until Tuesday? Will eating at all cause a rapid decay in the exposed dentin? Should I brush it clean after each meal? Thanks.