Teeth grinding in potbellies can be extremely annoying, it can sound like crushed rocks being ground together. In the wild, pigs grind their teeth to sharpen them with male pigs sharpening their tusks in this way. So in this sense, it’s perfectly natural for a pig to grind his teeth.
A domesticated pig will grind their teeth for a few reasons. If they are around 2 years of age, your pig could be teething and once that’s finished the grinding should stop or at the very least reduce. Your pig could also be distressed for some reason, so you might want to make sure that there hasn’t been any major changes in your piggie’s life or anything that might make your pig stressed for some reason. Remove the source of the stress and the grinding should cease. A third reason is that your pig could simply be happy and content! If this is the case, sadly lthere’s not much you can do to stop the grinding directly.
You can try to lessen the effect of the grinding by giving your pig a soft toy to chew – some of the dog chewtoys can be quite good for this purpose. At least your pig doesn’t bark.. it’s a much more annoying trait