The most significant characteristic of glass ionomer cement (GIC) as a restorative material is its fluoride release. This property provides a continuous local supply of fluoride ions, which helps in inhibiting secondary caries and promoting remineralization of adjacent tooth structure. While adhesion to dental tissues is important, the anticariogenic effect from fluoride release enhances the longevity and preventive capabilities of the restoration. Other characteristics, such as compressive strength and aesthetics, are secondary in comparison to its role in caries prevention. Thus, fluoride release is crucial for both restorative function and preventive dental health.

Reference: Sturdevant’s Art and Science of Operative Dentistry, 7th Edition.