A Critical Evaluation of Image Superimposition in Dentistry

Image superimposition currently serves as an essential tool for evaluating the effectiveness of treatment by overlaying 2 or more images taken at different time intervals. Superimposition has proved to be an integral diagnostic tool in terms of assessing procedural accuracy, growth patterns, possible changes in extraoral soft tissue, and overall direction of teeth displacement. Several superimposition protocols have been proposed in literature. Traditionally, superimposition was done on 2-dimensional lateral cephalometric radiographs. However, this approach has its limitations. The rise of 3-dimensional (3D) imaging, including computed tomography and cone beam computed tomography, has introduced more advanced diagnostic tools. These technologies enable the creation of volumetric 3D images, which can be used for 3D superimposition to evaluate changes in the dentocraniofacial area. The primary techniques for 3D superimposition include landmark-based methods, surface-based methods, and the more recent voxel-based superimposition. By incorporating soft tissue data, the development of a virtual 3D patient is possible, offering substantial benefits in the field of dental and craniofacial medicine. Moreover, 4-dimensional superimposition, which captures the dynamics of temporomandibular joint and mandibular movements, is shifting research toward the study of dynamic, rather than static, virtual patients. Additionally, the advent of artificial intelligence is revolutionizing superimposition by enabling automated processes, which are poised to transform clinical and research practices. Here, we explore the recent advancements in superimposition techniques and their potential implications in dentocraniofacial analysis.