What is the function of a liner in cavity preparations?

The function of a liner in cavity preparations primarily revolves around providing thermal insulation to the pulp of the tooth. Liners are used in situations where the dental pulp may be at risk due to the proximity of the cavity preparation to the pulp chamber. By placing a liner, the thermal conductivity is reduced, which helps in protecting the pulp from temperature changes that may occur due to the placement of restorative materials like amalgam or composite. This is crucial in minimizing post-operative sensitivity and maintaining the health of the dental pulp.

In addition to thermal insulation, liners can also offer some degree of chemical protection depending on the material used, but their primary role is centered on thermal insulation.