<human>: Summarize the given text in a few sentences.

This is something that's very embarrassing for me to talk about, please keep any negative opinions you have to yourselves. My boyfriend has struggled with oral hygiene for a really long time, it's only within the last couple of months that he's really started to rinse with mouthwash regularly. After an abscess that required two of his teeth be extracted we made a really good push to keep sugar out of the house and succeeded for a bit before relapsing. After that he had another abscess and had to have his front incisor removed, when he smiles he doesn't have any teeth to show on the top. 

Most nights he rinses, in the morning he's told me he does it before he goes in to work (after he leaves the house) but I found evidence that he'd been lying to me when I noticed the mouthwash I'd bought him to keep in the car hadn't been opened. I never approached him about it, eventually the bottle ran out and my boyfriend told me he'd refilled it from the one in the bathroom but this weekend when I cleaned the car while he was napping I didn't even find the empty container. Prior to cleaning the car, probably about a couple of weeks, I'd managed to bring up getting him a toothbrush and he agreed but it's still sitting unopened in plain sight. 

I have no idea how to approach an adult about something like this, and I don't know how to tell him to do it without sounding like I'm a mom addressing her child. We've had issues in the past resulting from my tone and phrasing so I don't trust my judgement going in to this.
<bot>: I need to start my boyfriend on a proper oral hygiene routine, and make sure that he maintains it without treating him like a little kid.