Image segmentation is an important processing step in many image, video and computer vision applications. It plays an important role in most subsequent image analysis, especially in pattern recognition and image matching. Several general-purpose algorithms and techniques have been developed for image segmentation. Since there is no general solution to the image segmentation problem, these techniques often have to be combined with domain knowledge in order to effectively solve an image segmentation problem for a problem domain. This paper presents a study of segmentation techniques that are usable in caries detection. As different choices of segmentation methods offered by the change of input image type, the presented review gathers with emphasize on this factor.