Traditional dental education has recommended the generous use of bases
and liners under amalgam restorations, primarily to prevent postopera
tive sensitivity. However, new developments in bases and liners, as we
ll as a better understanding of pulp biology, have changed the indicat
ions for the use of these materials. Understanding the properties of c
urrently available materials and how they interact with pulpal tissues
can help the practitioner decide when to use bases and liners and whi
ch products to choose.