Abstract
BACKGROUND: Comparative analyses of different adhesive systems have illustrated that variations in the content can substantially influence the effectiveness of bonding. While in vitro studies provide essential insights, it is imperative that clinical recommendations derive from randomized clinical trials to ensure their reliability and validity. This double-blind, split-mouth, randomized clinical trial was conducted to assess the performance of various universal adhesives over a 24-month period, with a specific emphasis on monomer type, HEMA content, and solvent type, using the selective enamel etch approach in non-carious cervical lesion (NCCL) restorations. MATERIALS AND METHODS: Thirty-two participants with two-hundred-fifty-six NCCLs were assigned to the two groups (n = 128): G-Premio Bond (GPB; GC) and Single Bond Universal (SBU; 3 M ESPE). The same composite resin (Essentia, GC) was used. Restorations were assessed at baseline, 12-month, and 24-month using the Revised FDI criteria by two blinded calibrated examiners. Statistical analysis included Fisher's Exact Chi-Square test, Continuity (Yates) Correction, and McNemar tests (p < 0.05). RESULTS: The 24-month success rate was 98.2%, with the loss of retention in four restorations-two from SBU and two from GPB. Throughout all evaluation periods, no significant differences were identified between the adhesives regarding any criteria (p > 0.05). Both adhesives exhibited a significant decline in marginal adaptation at both the 12-month and 24-month evaluations, as well as an increase in marginal staining at the 24-month interval (p < 0.05). Notwithstanding the observed decrease in marginal adaptation after 24 months, all restorations remained clinically acceptable and were classified as clinically satisfactory. CONCLUSIONS: A clinical analysis over a 24-month period demonstrated that variations in the composition of universal adhesives-specifically concerning monomer types, HEMA content, and solvent type-did not significantly affect the performance of NCCL restorations. Notably, all retained restorations met clinical acceptability standards. TRIAL REGISTRATION: The clinical trial was registered on 13/01/2021 at https//clinicaltrials.gov with the ID (NCT04707898).