Teeth continue to be in the focus in many paleontological and neontological disciplines, and their morphological characters, histological structure and mode of attachment are the subject of ongoing studies. In this review, we elaborate on tooth shape. We first highlight the progress that was made over the last two decades in understanding the mechanisms that determine the shape of a tooth. We then describe the often dramatic changes that tooth shape undergoes in ontogeny. Finally, we discuss characters of the dentition to which tooth shape may be intimately linked: tooth number and thus tooth spacing, as well as tooth replacement. While literature about various non-mammalian vertebrates is considered, this review focuses on the highly speciose teleost group.