Kathy, if you are asking if carbonated drinks are a causitive factor for oral cancer, the answer as far as I have read is a resounding NO. If, on the other hand, you are asking if they sting, yes, and for how long is an individual thing depending on how much radiation, whether there was also chemo, whether there was surgery, and just individual rates of healing and tolerance. And if I misunderstood your question entirely, please accept my apology.
Joanna