The modern concept of minimal invasive dentistry aims to preserve tooth structure through removal of highly infected, irreversibly demineralized, and denatured dentin only with preservation of affected dentin in order to allow effective restoration and to maintain tooth vitality. However, the boundary between the superficial zone of dentin which require excavation and the deeper affected one is not always feasible. The inherent subjectivity during the excavation of this boundary can lead to clinical significant differences in the quality and quantity of dentin being removed and can increase the risk of pulp exposure. Therefore, new methods have been developed to aid to identify the amount of dentin that should be removed during deep caries excavation.