I have bitten my nails for almost 25 years, since I was 6. I recently got myself to stop and it's been a good 2 months now since I've bitten them at all and I can honestly say I can't remember the last time I've had the urge to bite them. I probably had a moderate problem (bit my nails where they were always halfway down the nail bed but def more than a sliver of nail left). All I did was paint my nails with a nail strengthening clear coat EVERYDAY. Even if the polish was still there I'd reapply. This way I never got to the actual nail. I would bite/pick at the polish but not the nail til the nail got long and strong enough. I sometimes bite down on my nail but now that it's longer it's harder to bite off and this is enough to satisfy the oral fixation. I still paint my nails maybe weekly but I now have nails that extend past the finger. YAY!
I don't see it as a symptom of anxiety, but as an entrenched habit. Like all entrenched habits, it is hard to rid yourself of it. And like all habits, you have to want to quit.
I have heard a lot about this and my brother bit his nails all the time , it is a habit, he started doing it ,enjoyed it ,distracted him and kept it up.Maybe one has to break the habit, put something in its place ?
I know what you mean I have never been able to stop either... but I am hopeful to find something
Chronic nail biting is one symptom of anxiety. Have you considered this possibility?