several old posts in the OP forum (one of mine included) reported increased teeth sensitivity. an fyi. Yes, teeth get much whiter but so does the sensitivity.
Also: do you supplement or make sure to get enough C and B vitamins? These are related to teeth/gum sensitivity.
BTW: about the lemon question a few days back:
I too use both lemon and lime, but try to use mostly lemon because I have not found any reference to confirm that both offer the same benefits, and the material on lemon is so overwhelming.
As far a vit C, alkaline and antioxidant value though, I think it may be very similar or equal.