My daughter has been using my things as her own. How do I stop it?

Am I to approach my daughter about this or just let it slide? I am really wanting to let it slide but am not sure if that is appropriate. I have a very, very, very strong hunch that my daughter has been using my electric tooth brush for self-sex. It is only me and her in the house since her father divorced me 16 years ago. Suffice it to say, the past few weeks I've noticed a certain irregularity in the way my toothpaste and toothbrush taste when brushing. At first I thought it was nothing, maybe in my head or stemming from a mind flux or something. Then a while later I noticed it again and not I have noticed it almost every time I've brushed. Last week I started using a separate brush I kept in the drawer. The electric, which was thoroughly washed before I stopped using it definitely has the smell and taste I am referring to. I have never had any sexual talks with my daughter and we aren't close enough that I would feel comfortable doing that, so I have been on edge and ignoring it. I think its time to talk to her because my mouth doesn't feel as clean if I don't use that electric brush. I've had noticeable bad breath on multiple occaisons and once a coworker even called me 'skunk breath' in front of his fiance at a work get-to-gather. Humiliating to say the least. So how do I go about talking to my daughter about this? I am thinking of leaving her a note asking her to please stop.