Correlation between temporomandibular joint space and different degrees of anterior disc displacement: a systematic review

OBJECTIVES: This review aims to systematically summarize the current studies on the correlation between different degrees of anterior disc displacement (ADD) and temporomandibular joint (TMJ) space. MATERIALS AND METHODS: Study protocol was carried out based on the Preferred Reporting Items for Systematic Review and Meta-Analysis protocols (PRISMA). The PubMed, Scopus, Web of Science, and China National Knowledge Infrastructure (CNKI) databases were searched to find the relevant articles from database up to February 13, 2025. Studies that evaluated the correlation between ADD and TMJ spaces were included. We excluded intervention studies, case reports, case series, reviews, systematic reviews, opinion articles, book chapters, and studies involving populations with comorbidities potentially affecting the joints. The risk of bias was assessed using the QUADAS-2 tool. RESULTS: Of the 1109 articles retrieved, a total of 10 articles on the correlation between different degrees of ADD and TMJ spaces were included after evaluation of the title, abstract, and full text. Throughout different degree of ADD, variations in anterior joint space (AJS) and posterior joint space (PJS) exist due to condyle displacement. When the progresses further to ADD without reduction (ADDWoR), the superior joint space (SJS) becomes narrow. CONCLUSIONS: There was a stepwise correlation between the TMJ spaces and the degree of ADD. The AJS and PJS tend to be various in different ADD groups, and the SJS tends to be narrowed in ADDWoR patients. Future studies should standardize methodologies to validate its clinical applicability.