Condylar bone regeneration following temporomandibular joint disc repositioning surgery: a systematic review and meta-analysis.

OBJECTIVES: This systematic review and meta-analysis aimed to assess the impact of disc repositioning surgeries on condylar bone regeneration. MATERIALS AND METHODS: The study protocol adhered to the PRISMA 2020 checklist and Cochrane guidelines (CRD42024501867). The study included both randomized controlled trials (RCTs) and nonrandomized studies of interventions (NRSIs) (both observational and clinical trials) that reported radiological outcomes of condylar bone regeneration after disc repositioning surgeries were included. The focus was on joints exhibiting new bone formation and changes in condylar height. A comprehensive search across six databases (Embase, MEDLINE, CENTRAL, PubMed, Web of Science, and Scopus) was conducted to identify relevant studies up to February 2025. Additionally, reference lists of eligible articles were manually reviewed. The methodological quality were evaluated using the Methodological Index for Non-Randomized Studies (MINORS). The risk-of-bias assessment of the included NRSIs was conducted using the Risk Of Bias In Non-randomised Studies - of Interventions (ROBINS-I) tool. Random-effect meta-analyses were performed using STATA software with the metaprop and metan commands. RESULTS: Sixteen studies with a total of 1,457 patients met the inclusion criteria, including one RCT. Meta-analyses revealed that 89.3% (95% confidence interval (CI): 79.4%-96.5%) of TMJs demonstrated new condylar bone formation post-disc repositioning surgery. For patients under 21 years of age, this figure rose to 95.9% (95% CI: 91.1%-99.2%). On average, disc repositioning surgeries increased condylar height by 1.54 mm (95% CI: 1.18-1.89 mm), with a greater increase of 1.75 mm (95% CI: 1.41-2.10 mm) observed in patients under 21 years. Considerable heterogeneity was found in most meta-analyses. CONCLUSIONS: Disc repositioning surgeries appear to promote condylar bone regeneration, with more pronounced benefits observed in younger patients. However, the considerable heterogeneity among included studies and limited quality of current evidence necessitate cautious interpretation and call for future longitudinal studies with standardized protocols and long-term follow-up to confirm these preliminary results and establish more robust conclusions. CLINICAL RELEVANCE: This systematic review and meta-analysis indicated that restoring the disc position might be beneficial for condylar bone regeneration.