I hven't tried them all, but I think they're flavored the same IIRC.
Actually, the opposite regarding teeth! They are sugar alcohols, Xylitol to be exact. Low GI, so low insulin response and they actually IMPROVE oral health, particularly teeth. My dentist told me to get xylitol gum, so adding in some extra is bonus (in addition to the BCAA, etc.). I still have to look up more about that piece, I'll post up what I find.
FDA counts sugar alcohols as 2.4 calories per gram, though each alcohol really have different values. Each dose of PowerChews is 17 calories I believe.
Xylitol is definitely one of the better sugar alcohols out there from what I've read.