A device for the perforating extension of a blind bore introduced into a jawbone, includes a hollow body defining a hollow space and having a distal working opening and an inlet opening opposite the working opening, and being sealingly insertable into the blind bore, a working tool connected with the hollow body so as to form a common unit with the hollow body, a shaft arranged on the working tool and having a distal tool head for working on the jawbone, said shaft being insertable into the hollow space through the inlet opening, said distal tool head being at least partially guidable through the working opening for working on the jawbone, a connection fluidly connected to the hollow body for establishing an internal pressure in the hollow, and an adjustment mechanism provided in or on the device for axial movement or linear forward feed of the shaft in the hollow space along a longitudinal axis of the shaft and the hollow space
