“strike all of my enemies on the cheek.” In the biblical culture, striking someone on the cheek was an insult that disgraced them. It was not a deadly attack. In this context, the Psalmist wishes that Yahweh would insult and disgrace his enemies, and also disempower them.
[For more on the custom of striking someone on the cheek, see commentary on Luke 6:29.]
“shatter the teeth.” Besides wishing God would strike his enemies on the cheek, the psalmist wishes God would “shatter the teeth of the wicked.” Breaking someone’s teeth will not kill them, but it makes them powerless and harmless. The Psalmist is weary of being attacked by his enemies, and he wishes God would insult them, shame them, and make them powerless.