The Role of Two-dimensional and Three-dimensional Imaging in Tongue and Temporomandibular Joint Assessment: A Narrative Review

Radiographic imaging has long been integral to orthodontic diagnosis, with recent advances expanding its scope beyond hard tissues to include the tongue and temporomandibular joint (TMJ), both of which play critical roles in craniofacial growth, function, and malocclusion. This review summarizes current imaging modalities used to evaluate the tongue and TMJ in orthodontics based on a six-month literature search of PubMed, Web of Science, Scopus, and Google Scholar using relevant keywords related to orthodontic and functional imaging. Conventional two-dimensional imaging techniques, such as lateral cephalograms and orthopantomograms, continue to be valuable for initial assessment but are limited by image superimposition and inadequate soft-tissue visualization. Three-dimensional imaging modalities provide greater diagnostic accuracy and anatomical detail. Cone-beam computed tomography allows reliable evaluation of condylar morphology and tongue–oral cavity relationships, while magnetic resonance imaging offers superior visualization of soft tissues, TMJ disc position, and functional dynamics of the tongue without ionizing radiation. Ultrasonography represents a radiation-free, real-time imaging option, although its diagnostic utility is limited by reduced depth resolution. Emerging technologies, including cine-MRI, three-dimensional and four-dimensional ultrasound, and artificial intelligence–based image analysis, further enhance the assessment of both structure and function. Overall, orthodontic imaging has evolved from static, low-resolution techniques to advanced, dynamic, and volumetric modalities, enabling more precise diagnosis, individualized treatment planning, and evidence-based orthodontic care.