The present invention relates to a kit of parts for detection and removal of carious dentin tissue comprising: (i) one or more compounds being a hydrazine derivative, and (ii) means for chemical treatment of carious dentin tissue. Further, the invention concerns a preparation containing an active, caries-dissolving two-component liquid in the form of a first active, caries-dissolving component and a second component which reduces the aggressiveness of the active component to mucous membranes, a viscosity increasing substance and one or more compounds being a hydrazine derivative. The hydrazine derivative labels carious dentin tissue selectively and substantially irreversibly in the presence of healthy dentin tissue, which is useful in the context of caries removal.