Charles Spurgeon Commentary Job 19:18-20

"Even young children despise me; If I arise, they speak against me. All my familiar friends abhor me, And they whom I loved are turned against me. My bone cleaveth to my skin and to my flesh, And I am escaped with the skin of my teeth." — Job 19:18-20 (ASV)

There is no skin on the teeth, or hardly any, and, therefore, Job means that there was next to nothing of him left, like the skin of his teeth.