Post-operative sensitivity may be minimized with the use of protective materials that will act on the dentin–pulp complex, such as glass ionomer cement, calcium hydroxide and resin-based adhesive systems. These materials must present bacteriostatic and bactericidal characteristics, protect the pump against thermal or electrical stimuli, and have good compatibility with the pulp and restorative material. It is desirable for these characteristics to be present simultaneously, however, there is still no material that presents all these features. The professional must have full knowledge of the type of action that is required for each cavity in order to select the best protective material possible. Consideration of the need for mechanical protection (tubular obliteration) or biologic protection (need for a material with greater biologic compatibility and capacity to induce reparative dentin formation) may be the key to improved protection of the dentin–pulp complex.