A system for carrying fluids through capillary tubes, especially for endodontic use, comprises an on-off valve for the gas given off by bubbles present in the liquid in circulation. The valve includes a cavity in which is a lower chamber adjoining a wider upper chamber having a mouth communicating with the environment. The lower chamber has two mouths respectively for inflow and outflow of the liquid. The valve includes a means for obstructing the passage between the lower and upper chambers, said means of obstruction being free to translate vertically, under pressure from the gas given off by the bubbles, and including a small cylindrical body surmounted by a disk and an o-ring wrapped around the cylinder. A peristaltic pump is set so as to alternate periods of operation with short periods of rest, baric balance with the environment being established within- the pulp cavity of a tooth to be devitalized situated halfway along the hydraulic circuit.
