Self-Adhesive Flowable-Resin Composites: From Chemistry to Clinical Evidence—A Critical Review

Self-adhesive flowable-resin composites (SAFRCs) incorporate acidic functional monomers to bond to tooth structure without a separate adhesive. This critical narrative review relates the composition of eleven products identified in September 2026 to laboratory properties and clinical outcomes. A structured search of PubMed/MEDLINE, Scopus and Web of Science identified 69 reports for qualitative synthesis; study design and methodological limitations informed interpretation, without formal risk-of-bias assessment. Acidic monomer-mediated adhesion provides a general framework, but interactions with tooth tissue and interfacial stability vary by formulation. Laboratory studies generally report lower dentin bond strength than adhesive-based controls and improved enamel bonding after phosphoric-acid etching. Water uptake is often high, although results obtained under non-standard conditions cannot establish non-compliance with ISO 4049. Selected S-PRG-containing formulations show favourable mechanical, bonding or ion-release properties in vitro; 10-MDP-containing products do not consistently show higher bond strength. Ion release and surface antibacterial activity do not establish clinical remineralisation or caries prevention. Clinical findings are heterogeneous and product-specific, with most follow-up limited to 24 months and one trial extending to 5 years. They support cautious consideration of the tested products for small, retentive Class I restorations, without establishing equivalence to conventional protocols or efficacy across the material class. Laboratory evidence and product instructions inform selective enamel etching; its incremental clinical benefit remains untested in direct randomised comparisons.