There are many that are not only useful, but essential to oral health.
You can supplement with probiotics, which have been proven in quality studies to improve mouth/nose/throat health, and, to a lesser extent, even prevent caries. The bacteria cultures are known by their shorthand K12 and M18, respectively. In New Zealand this is part of official health guidelines.
On phone so can't look for references but look it up, it is well supported.
