Bioactive ion-releasing restorative materials: a critical narrative review of terminology, evidence and controversies

Bioactive ion-releasing restorative materials are marketed as an advance over inert resin composites because they release fluoride, calcium, phosphate or silicate ions intended to inhibit caries and promote remineralization. This narrative review examines the terminology, the laboratory and clinical evidence, and the controversies that separate those claims from measured performance. A documented search of PubMed, OpenAlex and Crossref identified studies published mainly between 2019 and 2026, supplemented by classic methodological references. The term bioactive is applied inconsistently; the FDI policy statement requires local, intended and nontoxic effects that do not compromise the restorative function. In vitro, glass ionomer cements release fluoride over time and can be recharged, whereas bioactive glasses, surface pre-reacted glass and calcium silicate fillers precipitate apatite in simulated body fluid, yet these surrogates do not predict clinical benefit. Clinical evidence supports a lower incidence of secondary caries for glass ionomer than for amalgam (risk ratio 0.20 in permanent teeth) and a similar incidence relative to resin composite, while glass ionomer and composite restorations show comparable survival in primary teeth and noncarious cervical lesions. Evidence for newer bioactive composites and alkasites remains short term and largely laboratory based. The central controversy is the translational gap: terminology and in vitro bioactivity outpace clinical data. Standardized terminology, surrogate validation and longer trials with caries-related outcomes are needed.