Only one of my lops has no sign of dental disease and she is a manic hay eater so I personally feel that has an awful lot to do with it. TBH I don't think it's a myth that lops are more prone to dental disease, it's factually based on their skull mutations & genetics. The majority of the lops I had in when I was rescuing showed some evidence of spurring or misalignment of the molars when neutered, indicating they may experience issues at some stage in future if not at the present time.
I havn't encountered any lops with incisor maloclussion personally though, so this dosn't appear to be as common, though I know a breeder round here is churning them out with under & over bites. :?