Why is glass ionomer cement used as a cavity liner in dental procedures?

Glass ionomer cement is often used as a cavity liner in dental procedures due to its non-irritant properties, which make it biocompatible with the dental pulp and surrounding tissues. This characteristic is crucial in protecting the pulp from irritation that can be caused by other filling materials or external stimuli, especially in cases where the cavity preparation has approached the pulp or in procedures involving sensitive teeth.

Additionally, glass ionomer cement acts as a barrier, reducing the risk of postoperative sensitivity and ensuring patient comfort. By being non-irritant, it supports the healing process of the dental tissues and ensures a more favorable environment for the restoration's longevity and success. While other properties such as its ability to release fluoride and its compatibility with filling materials are important, the defining feature for its role as a cavity liner is its non-irritant nature.