What is the final setting reaction for glass ionomer?

The final setting reaction for glass ionomer involves the crosslinking of polyacrylic acid polymer chains. This process occurs after the initial reaction between the acid and the glass powder containing calcium and aluminum ions. During setting, as the acids interact with the ionomers, they facilitate the release of ions from the glass components which leads to the polymerization and subsequent crosslinking.

This crosslinking is crucial because it enhances the structural integrity and mechanical properties of the glass ionomer, allowing it to function effectively as a dental material. As polyacrylic acid polymer chains crosslink, the material achieves its final hardness and stability.

The other options, while they may describe relevant aspects or secondary effects associated with glass ionomer, do not encapsulate the primary reaction responsible for the final setting. For instance, the formation of phosphate gel or the release of fluoride ions happens during the initial stages of the setting process or as a feature of its properties, but they do not represent the culmination of the setting reaction itself. Hydration of the polymer matrix also contributes to the setting process but does not specifically define the final chemical changes that occur.