I've had my Invisalign fixed retainers in for two years along with the night guard (can't remember the name) which I use for 4 nights a week.
They've broken three times during that time. The dentist (one of the biggest, reputable dentists) has said that it might be because of my heavy bite and also because I grind my teeth (the night guard has actually broken due to the pressure).
She has said I might be better off jjst having the fixed retainers removed entirely and wearing the night guard ecery night instead.
Does anyone else do this and/or have any advice on what to do?