Maintaining healthy pulp tissue and preventing apical periodontitis form the basis of minimally invasive, biologically based vital pulp treatment (VPT). This chapter aims to analyse current evidence on VPT, including the defensive response of the dentine-pulp complex to irritation and the diagnosis and management of teeth with deep carious lesions and pulp exposures. The American Association of Endodontists endorsed the currently accepted classification of pulpal disease in 2013, describing pulpitis as either reversible or irreversible depending on clinical signs and symptoms. An indirect pulp therapy addresses the excavation of deep carious dentine aiming to avoid pulp exposure. Although several factors influence the outcome of VPT, a principle determinant is the preoperative inflammatory state of the pulp, with carious pulpal exposures generally having a less favourable outcome than traumatic or mechanical exposures. Notably, in extremely deep carious lesions, there is ‘radiographic evidence of caries penetrating the entire thickness of the dentine with certain pulp exposure’.