Clinical Performance and Survival of Bulk-Fill Resin Composite Posterior Restorations in Primary Teeth: A Systematic Review and Meta-Analysis.

Background/Objectives: This systematic review and meta-analysis aimed to evaluate the clinical performance and survival of bulk-fill resin composite restorations in posterior primary teeth, compared with conventional resin composites and glass ionomer cements (GICs). Methods: The protocol was registered in PROSPERO (CRD42024539097) and conducted according to PRISMA guidelines. Electronic searches were performed in PubMed, Embase, Web of Science, Scopus, and Cochrane databases up to December 2025. Randomized clinical trials (RCTs) evaluating bulk-fill resin composite restorations in primary molars were included. Restoration survival was considered the primary clinical endpoint. Secondary outcomes included marginal integrity, marginal discoloration, color match, postoperative sensitivity, secondary caries, retention, and anatomical form, assessed using USPHS or FDI criteria. Meta-analyses were performed for color match, marginal discoloration, and marginal integrity using a random-effects model. Comparisons involving GICs were synthesized descriptively. Risk of bias was assessed using the RoB 2 tool, and certainty of evidence was evaluated using GRADE. Results: Six RCTs involving 1220 restorations in children aged 3 to 10 years were included, with follow-up periods ranging from 6 to 24 months. Survival rates were high across all materials. Meta-analyses up to 12 months showed no significant differences between bulk-fill and conventional resin composites for color match, marginal discoloration, or marginal integrity. Most RCTs were judged as having low risk of bias, with one study presenting some concerns. The certainty of evidence was rated as moderate, mainly due to imprecision related to sample size and limited reporting of confidence intervals. Conclusions: Bulk-fill resin composites demonstrate clinical performance and survival comparable to conventional resin composites in posterior restorations of primary teeth over follow-ups of up to 12 months. Based on RCTs with predominantly low risk of bias and moderate certainty of evidence, bulk-fill composites represent a reliable and efficient restorative option in pediatric dentistry.