2025-12-302025-12-302025MENDONÇA, Thaís Silva et al. Clinical performance of posterior resin composite restorations bonded with universal adhesive system using three different application modes: a 26-month randomized clinical trial. Journal of Applied Oral Science, Bauru, v. 33, e20250402, 2025. DOI: 10.1590/1678-7757-2025-0402. Disponível em: https://www.scielo.br/j/jaos/a/X5JJrnHgzzKpQ8pBbzQmLBB/?format=html&lang=en. Acesso em: 17 dez. 2025.1678-7757e- 1678-7765https://repositorio.bc.ufg.br//handle/ri/29286Objective This study aimed to evaluate the clinical performance of posterior resin composite restorations (Class I and II), bonded with a universal adhesive using three application modes over 26 months, comparing the adapted FDI and USPHS criteria. Methodology In total, 138 Class I and II cavities were restored using Scotchbond Universal adhesive (3M ESPE) in three application modes: etch-and-rinse (ER); selective enamel etch (SEE), and self-etch (SE). All cavities were restored with FiltekTM Supreme composite resin (3M ESPE). The restorations were evaluated by two trained and calibrated evaluators using FDI and adapted USPHS criteria at baseline (12.02±5.68 days) and after 26 (± 2.36) months. The obtained data were subjected to statistical analysis between the groups using the Friedman and Wilcoxon test for intra-group analysis and the McNemar test for comparisons between FDI and USPHS criteria (α=0.05). Results No statistically significant differences were observed between the ER, SEE, and SE groups after 26 months, except for marginal discoloration between the ER and SE groups (p≤0.05). Conclusion Class I and II resin composite restorations performed with Scotchbond Universal adhesive using ER, SEE, and SE modes showed acceptable clinical performance over a 26-month evaluation period. Moreover, the adapted FDI and adapted USPHS criteria yielded comparable results. Brazilian Clinical Trials Registry (Rebec) — RBR-9p3hdpengAcesso Abertohttp://creativecommons.org/licenses/by-nc-nd/4.0/Universal adhesivesRandomized clinical trialDental restorationsClinical longevityArtigo10.1590/1678-7757-2025-0402