Final answer:
The initial setting reaction for glass ionomer is a fast acid-base reaction that results in early strength and adhesion to dental structures.
Step-by-step explanation:
The initial setting reaction for glass ionomer cement is primarily a acid-base reaction. When the powdered glass, which is basic, comes into contact with the acidic polymeric liquid, they react to form a cross-linked matrix that initially sets quite quickly. This matrix is responsible for the material's early strength and adhesion to dental structures. The rate of reaction for glass ionomer cement can be considered relatively fast in the early stages, which is beneficial since it rapidly achieves initial set and can begin to withstand the oral environment.