Bonding behavior of graphene-based enhanced restorative materials: a systematic review and meta-analysis

Objective This systematic review and meta-analysis (SRM) aimed to investigate the efficacy of graphene-based materials on dentin adhesion in resin composites. Methods This SRM was conducted following the PRISMA statement and was registered in PROSPERO (CRD42024614838). A systematic search was conducted in Medline/Web of Science/Scopus/Embase/Cochrane Library, for articles published until September 2024. Eligible studies included in vitro studies evaluating the use of graphene-based materials in resin-dentin adhesion, excepting those without controls, on animals, non-dentine-focused, material-only, or reviews. Data were extracted and Meta-analysis was performed using Rev Man software. A modified Joanna Briggs Institute's Checklist was used for risk of bias assessment. Results Of the 694 records screened, 9 studies were included. Graphene-based materials exhibited effects on the improvement of bond strength to dentin. Dentin shear bond strength was significantly enhanced, particularly at 1 % (MD[95 % CI] = 2.30[1.88; 2.72], P < 0.00001) and 2 % (MD[95 % CI] = 20.41 [7.86; 32.95], Р = 0.001) concentrations, while lower concentration 0.25 % (MD[95 % CI] = 3.25 [-8.30; 14.79], P = 0.58) had minimal effect. Microtensile bond strength showed mixed results, with lower initial bond strength but comparable performance to conventional materials over time. Push-out bond strength varied, with one study showing improved bonding and another showing no difference. Graphene incorporation reduced adhesive failure and cohesive failure, and some materials exhibited less microleakage. Overall, the studies presented a low risk of bias. Conclusions Graphene-based materials have shown promise in enhancing dentin adhesion and bond strength in vitro, suggesting their potential to improve adhesive restoration outcomes in clinical practice. However, variability in protocols and limited long-term data, including aging by water storage, prevent definitive clinical conclusions. Future research should focus on standardizing methods, evaluating long-term performance, and assessing biocompatibility.