Edgar Cochran’s review published on Letterboxd:
Serial killers are generally diagnosed with Antisocial Personality Disorder and Narcissistic Personality Disorder, but those suffering from Borderline Personality Disorder fall into activities involving self-inflicted damage. They are considered to be more self-destructive. With Buttgereit's past takes on pain and death as transcendent elements of human existence, he chooses to take the latter group and make a feature based on such suffering. Jeffrey Dahmer, for example, aka "The Milwaukee Cannibal", was apprehended a couple of years before this film's completion. He was placed charges on the rape, murder and dismemberment of seventeen boys and men between 1978 and 1991. Some of these murders were subsequently backed up with evidence involving cannibalism, necrophilia and preservation of body parts. He was, as a matter of fact diagnosed with at least three personality disorders: Borderline Personality Disorder, Schizotypal Personality Disorder and psychosis.
It wouldn't be bold to claim that Buttgereit showed interest in these matters being influenced by real-life cases and decided to opt more for a psychological approach with emotionally surreal juxtaposed undertones as he delves in the mind of a serial killer more loyal to the invigoratingly absorbing psychological perspective of Angst than with the extreme Narcissism of Noé's butcher in Carné (1991) (his approach would be much more psychologically analytical in 1998) or with the profile character study of Henry: Portrait of a Serial Killer (1986).
Despite his infamous graphical nature, Buttgereit is still a poet of his own philosophies. He treats his ideas of pain, asassination, death and necrophilia with relentlessness and honesty, but also with an empathetic sense of acceptance of these individuals without justifying or glorifying these unfortunate outcasts of society that are dangerous to others just as they are dangerous to themselves. That is why he is so underseen and misunderstood. People are either unwilling to approach extreme cinema which is almost always associated with gratouitous and meaningless exploitation when interesting and even socially concerning topics can be handled with this type of essays that must resort to a graphical nature to back up their ideas.
Now I know where the idea of Teeth (2007) came from.