A hard lump on the roof of the mouth may be a bone growth called a torus, according to Merck Manuals. These growths do not pose a health risk and are generally left untreated unless they cause difficulties while eating or a person requires dentures.
A person may have a digestive tract disorder called familial adenomatous polyposis if the individual develops multiple toruses on the roof of the mouth, notes Merck Manuals. This condition is hereditary and often signals the presence of colon polyps that can progress into cancer. Toruses are most common in women over 30 years of age and people who grind their teeth, according to the American Academy of Otolaryngology. Bumps on the roof of the mouth can also develop as a result of fever blisters, but it is not common for them to form in this location, and they are not hard. Fever blisters are usually accompanied by a fair amount of pain and often burst soon after they form, leaving an open wound that makes it difficult to eat. They subsequently crust over and take up to 10 days to heal. People who are concerned about growths in the mouth should visit a doctor or dentist to perform a visual exam and make a proper diagnosis.