A Preliminary Novel CBCT-Based Staging System for Temporo-Mandibular Joint Disorders—A Systematic Review

Background and Objectives: Temporomandibular disorders (TMDs) are heterogeneous conditions that may involve structural alterations of the temporomandibular joint (TMJ). Although cone-beam computed tomography (CBCT) enables detailed assessment of osseous structures, existing classifications mainly address clinical diagnosis, internal derangement, or isolated imaging findings. This review aimed to identify recurrent TMJ osseous changes and develop a practical CBCT-based staging system. Materials and Methods: The review was conducted according to PRISMA 2020. PubMed, Embase, and the Cochrane Library were systematically searched, supplemented by citation and grey-literature searches. Methodological quality was assessed using the Newcastle–Ottawa Scale, Joanna Briggs Institute tools, and AMSTAR 2, while evidence certainty was evaluated using GRADE. Recurrent imaging findings, clinical correlations, prognostic implications, and therapeutic perspectives were synthesized to develop the proposed scale. Results: Sixty-seven peer-reviewed studies were included, while 12 grey-literature records were retained as complementary evidence. Frequently reported findings included condylar flattening, erosion, sclerosis, osteophytes, cortical alterations, subchondral cystic changes, joint-space abnormalities, remodeling, dimensional reduction, and deformation. Imaging-clinical correlations were heterogeneous. The synthesis supported a four-stage system ranging from preserved osseous morphology (Stage I), through early positional/adaptive changes (Stage II) and established remodeling (Stage III), to advanced structural degeneration with marked deformation and joint-space collapse (Stage IV). Conclusions: CBCT-detectable TMJ osseous changes can be organized into a four-stage severity framework intended to standardize structural assessment. The scale should complement, rather than replace, clinical diagnosis or MRI evaluation and requires external and longitudinal validation before routine clinical use.