I'm onto the retainer stage of my Invisalign and am keen for them not to get too grubby.
I used toothpaste or a retainer cleaning tablet when I was doing the aligner trays but even so, they got a bit cloudy towards the end of the week. It didn't bother me so much as by then I'd be swapping to the next tray but there won't be any of that with the retainers.
Has anyone tried one of those little ultrasonic retainer/denture cleaning machines? Do they work or are they just gimmicks?