Christian Bale's teeth have played a significant role in his on-screen transformations. His natural teeth, along with any enhancements, have helped him achieve a range of looks, from the sharp and clean-cut appearance in American Psycho to the grittier, more rugged look in films like The Machinist and The Dark Knight trilogy. Bale's attention to detail, including his teeth, is part of what makes his character portrayals so compelling and believable.