what about the tooth then?
was there ever even a tooth or cracked wallpaper behind the dresser? was that a figment of his imagination?
shareA couple years late, but my interpretation (which is not necessarily "fact") is that yes, there was a tooth hidden in the wall. It is Trelkovsky's tooth, and Trelkovsky himself extracted it and put it there.
Why?
Watching this film, I get a strong sense of Trelkovsky's shame and repression. He convinces himself that the tenants are doing certain things to him, when in reality he himself wants to do these things -- and in fact does do them -- but he represses all memory of it. He claims the tenants spend hours in the common bathroom, staring at him from the window. But isn't he the real voyeur, sitting at his own window with binoculars poised, constantly staring at them? He wakes up one morning with makeup on his face, certain that the tenants broke into his apartment and applied it while he slept. But in an earlier scene, we saw him linger with fascination over Simone Choule's possessions, even trying on her nail polish. Could we not conclude that Trelkovsky himself put on the makeup, but repressed the act because he was ashamed?
Likewise with the tooth. When he is with Stella in her apartment, he recounts the story of a man who lost a leg; and he wonders aloud how much of one's body one can lose while still retaining the essence of one's self. When he arrives home, we see him examine his face in the mirror, touching his jaw as if he is actually considering removing a tooth. If he chips away at his body, even a small part of it, can he amputate those traits of which he is so ashamed? I believe he attempts just that. A few scenes later (IIRC), he wakes with a bloody mouth and finds the tooth in the wall.
His misplaced shame turns to paranoia, as he feels the disapproving tenants will never simply let him be, but must pursue him and change him.