Effects of Additive Incorporation on Fluoride Release of Orthodontic Glass Ionomer Cements and Adhesives: A Systematic Review

This systematic review evaluated the effects of functional additives on fluoride release, fluoride recharge/re-release, and selected mechanical, physical, and biological properties of orthodontic glass ionomer cements (GICs) and glass ionomer-based adhesives. The review followed PRISMA guidelines. The protocol was retrospectively registered in the Open Science Framework. PubMed, Scopus, Web of Science, Embase, and WorldCat were searched for in vitro studies investigating modified orthodontic GICs and reporting fluoride-related or clinically relevant material properties. The final literature search was conducted on 30 April 2026. After screening 87 records, 23 studies were included in the qualitative synthesis. Owing to substantial methodological and outcome heterogeneity among the included studies, no meta-analysis was performed, and the findings were synthesized narratively. Risk of bias was assessed using the QUIN Tool; 20 studies were classified as having a medium risk of bias and three as having a low risk, while none were classified as having a high risk. The effects of additives on fluoride release varied according to additive type and concentration, material composition, storage conditions, pH, and evaluation period. Increases in fluoride release were reported in studies evaluating materials containing nCaF2, TMPnano, nanofluorapatite or nanofluorohydroxyapatite, hydroxyapatite, nanochitosan, SNP/ZnONP, and ZnSO4. Several additives maintained or improved mechanical performance, whereas higher concentrations of some agents adversely affected bond strength, microhardness, or material stability. Antibacterial and antibiofilm activity was most evident for CHX, DMAHDM, MDPB, propolis, silibinin, nanosilver, and zinc-containing systems. Limited evidence also suggested potential benefits regarding enamel protection and cytocompatibility. Functional additives may enhance the preventive potential of orthodontic GIC-based materials, particularly through improved fluoride release and antibacterial activity. However, further standardized long-term and clinical studies are required before clinical recommendations can be made.