From what I understand these would be complementary: the advantage of a probiotic solution would be that you basically get the treatment from time to time then never have to care about periodontal disease (which affects almost half of the US population [1]) or tooth decay, and then just have to brush your teeth or tongue to freshen your breath (but without long-term consequences if you don't).

[1] http://www.perio.org/consumer/cdc-study.htm