Vronsky is pacing and pretends not to see Koznyshev; Koznyshev thinks it is his duty to respect Vronsky for going to war. Koznyshev offers to write Vronsky a letter introducing him to influential people, but Vronsky says that his life has no value to him and that the only thing he’s good for is physical energy. As he and Koznyshev walk, Vronsky's tooth begins to ache. A vision of Anna’s corpse suddenly flashes before his eyes, and sobs distort his face for a few moments before he regains control to finish speaking with Koznyshev.
But Anna’s death does have the emotional impact she desired: without her, although Vronsky presents a stoic front, he is crumbling on the inside. Vronsky used to have extremely strong, robust teeth, whereas Karenin was the one always getting the toothache. Teeth are an important marker of both physical and emotional vigor throughout the novel; Vronsky’s toothache here mirrors his grief.