Retainers are probably the

most gross things on the planet. I have had the same one for 10 years and it probably has every kind of bacteria known to man on it. Sure I brush it occasionally and dunk it in mouthwash once in a while but that can't kill everything. Well, maybe the mouthwash can since it has alcohol in it but I doubt toothpaste does much. I am about half curious as to what would show up if someone did a bacteria culture on it. I say half curious because I still have to wear it in my mouth afterward.