1. Buckteeth patients dare not laugh. People with buck teeth will naturally show their teeth when they don't laugh, but they will show their teeth more when they laugh, so people with buck teeth are usually afraid to laugh.
2. Buckteeth patients are afraid to communicate with others. Buckteeth often make people feel inferior. They always feel different from others, so they are afraid to communicate with others.
3. Buckteeth patients are very insecure. Because they dare not communicate with others, they dare not laugh, which eventually leads to people who are grinning.