There isn't one. The recession of gums has nothing to do with soft plaque.
Preventing soft plaque is not going to cause that tissue to grow back as the enzymes that have been released into that tissue like collagenase, elastase, fibrinase, and inflammatory biomarkers like TNFa are there to stay as long as the biofilms are there to stay.
If you try and push the biofilms out with aggressive antibiotic usage then the biofilms push back by releasing more enzymes to breakdown more of the tissue for them to feed upon. It seems like in theory if you could somehow improve immunity to be hyper resistant against oral pathogens then the oral cavity would be in such an environment that elements of that microbiome that might aid in tissue regeneration might be able to flourish. Microbiome science is in its infancy though even now, so no such thing has been discovered as of yet and everything points to the fact that once a non-complimentary biofilm has taken root in a tissue that isn't your gut, it's there to stay for the longhaul. Doing things for your gut will improve immunity, but given that the bacteria that inhabit the oral cavity have nothing to do with the gut, probiotics and such is not doing much of anything for the situation, and antibiotics will definitely make the situation worse. Sub-clinical doses of doxycycline, about 20mg a day have been found to prevent the bone resorption though accelerated by the biofilms in plaques and oral tissue by inhibiting MMP's which will lessen the rate of decay below the gum line which might lessen gum recession