Hastings' Dictionary of the Bible (1898)
TOOTH. The law of retaliation allowed the Jewish magistrate to give to one who had been deprived of a tooth or an eye the tooth or eye of the aggressor in revenge. Ex 21:24. The Jews construed this law to justify private revenge, and this construction and the whole principle of the law were condemned by our Saviour, and the law of forbearance and forgiveness commended. Matt 5:39. Cleanness of teeth is a figurative expression for famine. Am 4:6.
Gnashing the teeth indicates terror, rage, and despair. Matt 8:12. The phrase in Eze 18:2 denotes that the children suffer for the sins of their fathers.