The contours of the teeth are important features in dental biometrics. They can be utilized as cues for identifying individuals. The extraction of other features (e.g., the dental work) also needs the contours of teeth as reference. However, without the proper guidance of tooth shape knowledge, these methods are subject to errors when the tooth contours are fuzzy and only partially visible. To extract the contours from these images, the authors propose a method based on edge detection, and an extraction method by using binary template and knowledge based model.