Disclosed is a method, and a system, for accomplishing the in situ formation of a gel in an interdental space. This is useful for the interdental application of one or more dental care agents, such as antimicrobial agents or other anti-plaque agents. The invention makes use of a two component system comprising a gelable liquid and a liquid gelling agent capable of bringing about gelation of the liquid. The system of the invention is arranged such that first the gelable, typically viscous, liquid can be applied, and then the liquid gelling agent is forced, e.g. jetted, into the applied gelable liquid. The system is designed such as to prevent the gelling agent and the gelable liquid to come into contact with each other before both have been applied. The system is configured to allow the gelable liquid to be applied prior to the gelling agent.