I have a proper clean at the dentist every six months and keep up good oral hygiene in-between
As reagrds mouthwashes to kill bacteria: when I was having a wisdom tooth out last year in hospital I had to gown up and everything before I went into the operating theatre. Once there I asked why they weren't giving me anything to sterilize my mouth. I was told that it was impossible to kill all the bacteria in the mouth as there are so many different kinds (I was taking prophylactic antibiotics to protect my valve). This got me very interested in oral bacteria - there can be 100 different kinds, some of them beneficial and some of them harmful. I now take a specific oral probiotic which contains beneficial bacteria. There will still be harmful bacteria around, since our mouths are open to the air and what we put in them so we get all sorts come in, but if you can encouarge the beneficial ones they can have the most effect. and crowd out the bad guys. But you can't kill all the bacteria !