I Have a Hard Lump in My Mouth. Is It From Grinding?
Most likely it is a torus — a lump of ordinary bone, either on the inside of the lower jaw beside the tongue or as a ridge down the centre of the palate. It is not a growth and not dangerous. Tori are common in people who clench and grind. They need no treatment unless they get in the way of a denture. Have it confirmed rather than assumed.
What a torus feels like
Bone-hard, because it is bone. It does not move, it is covered in gum that looks the same colour as the rest of the mouth, and it is painless unless you catch it with a toothbrush or a crisp.
They sit in two predictable places. A torus mandibularis is on the inner surface of the lower jaw, level with the premolars, beside the tongue — usually one on each side and roughly symmetrical. A torus palatinus runs down the midline of the roof of the mouth as a ridge or a row of bumps.
Most people discover one by accident in their thirties or forties and assume it has appeared overnight. They grow slowly over years, which is why they tend to be noticed rather than watched arriving.
Why grinding comes into it
Bone responds to load. The current understanding is that tori form where heavy, repeated force is transmitted through the jaw in someone already predisposed to lay bone down that way — so clenching and grinding is associated with them, and they are more common in people who do it.
There is a family tendency too, and the trait is more common in some populations than others. So a torus is not proof you grind, and grinding does not guarantee you will get one. What it does do is make the question worth asking.
That question is the useful part. If you have tori and did not know you clenched, it is worth looking at what else heavy loading may be doing: worn or flattened biting surfaces, teeth that have become sensitive, cracks, a jaw that aches in the morning, headaches at the temples. Those are the things that cost you teeth. The lump itself is harmless.
When a torus actually matters
Rarely, and for mechanical reasons rather than medical ones. A large one can be caught by a toothbrush often enough that the gum over it stays sore. It can make a lower denture impossible to seat, which is the usual reason one is removed. Occasionally a very large palatal torus affects speech or makes an impression difficult.
Otherwise it is left alone. Removing a torus is minor oral surgery, and there is no benefit in removing one that is not causing a problem.
What else a hard lump can be
This is the reason to have it looked at rather than read about it. Most hard lumps in those two positions are tori, but not all lumps are, and a few are things that should not be assumed away.
Worth being seen promptly for: a lump that is growing noticeably, one that is painful, one that bleeds or ulcerates, anything on the side of the tongue or the floor of the mouth, numbness, or a lump that appeared on one side only with no matching one opposite. None of those means something is wrong — it means the question deserves an answer rather than a guess.
Confirming a torus takes a look and sometimes an X-ray. It is a short appointment and it closes the question.
Questions
Is a torus cancer?
No. A torus is normal bone, covered by normal gum, and it does not become cancerous. That said, the reassurance should come from someone who has looked at it rather than from a description, because other things can present as a lump and a few of those do need attention.
Should I have it removed?
Only if it causes a problem. The usual reasons are a denture that will not seat over it, or gum that is repeatedly traumatised because the torus sits where the toothbrush goes. Removing one that is doing no harm means minor surgery for no gain.
Does having a torus mean I grind my teeth?
Not by itself. Tori are associated with clenching and grinding, and also run in families, so plenty of people have them without a heavy bite. What it is worth doing is checking for the other signs of grinding, because those are the ones that damage teeth.
Will it keep growing?
Usually very slowly, and often it stops. A torus that is visibly changing over months rather than years is worth showing someone, because that is not the usual pattern.