His teeth have strong dentin, making them less prone to cavities.

Toothed whales are a type of marine animal, and as the name suggests, they have teeth.

He is listening to music using Bluetooth.

When he eats an apple, he uses his incisors to bite it off.

He is conducting research on the radula of mollusks.

He is always cheerful and believes in the proverb 'Fortune comes in by a merry gate.'

Him laughing at other people's mistakes is just like the pot calling the kettle black.

He likes to take a walk in the park at dusk.

Since he is always laughing, it can be said that 'fortune comes in by a merry gate'.

He gritted his teeth to bear the pain.