You should definitely ask your dentist about this. Teeth are always supposed to be in contact with their adjacent peers in the dental arch, they touch passively. So if there is an area that you have difficulty flossing
it is like that there is something wrong at that contact. Floss frays or catches when the is a cavity
, calculus, an irregularly contoured filling or an overhanging margin. Those things need to be checked for by your dentist.
It is entirely possible that the ares of decay started years ago when you were young, and that the small defect that started long ago, are breaking down and allowing the decay to penetrate deeper.
neil mcleod dds
that lasts - quality that counts.