Doesn’t your mouth taste bad if you just don’t do it regularly? Honestly even general hygiene concerns aside, I’d do it twice a day just to get the fresh feeling. Maybe you could try some different toothpastes to find one that makes you really want to do it and not just feel like it’s something you should do?
Can’t the two of them just reproduce? Granted, I’m not a ninja scientist, but I think that’s how it works.