1. Rapid enlargement of oral mass: If a growth in the mouth increases in size quickly, remains unchanged for a long time, and is accompanied by symptoms such as bleeding and numbness. 

2. Ulcer persists for more than 2 weeks: Normally, with diet and medication, ulcers should improve within a short period of time.

If there is no healing after two weeks, caution is necessary. 

3. Abnormal gums: When there is swelling around the gums, it can cause nearby teeth to become loose or fall out.