Cool.  letting them think that the toothbrush is a fun toy really helps!  Ella thought tooth-brushing was great for the first month or so.  But since then she's hated having her teeth cleaned, especially the top ones - we'd sing her a silly song for it, but only when her mouth was open, and as soon as she clamped shut the song was over, then started up again once she opened - that worked for a month-ish, then we just had to do the brush'n'sob for lack of a better alternative, and now if her dad sits down and tips her back along his lap and pretends to laugh hysterically, she'll laugh back for long enough to get the job done.  It's a bit of a performance here, sorry.  That mightn't be reassuring for you!