Abstract: The invention concerns a disposable injection syringe, in particular in the field of dentistry, comprising: a syringe body provided with a needle at one first end thereof, the needle comprising an external part extending outside the body and an internal part extending inside the body, the needle forming an end external to the body and an end internal to the body; means for grasping the syringe body, at a second end thereof opposite the first end; a mobile injection rod; a cartridge containing a product to be injected, arranged inside the body between the needle internal end and the body second end in an inoperative position, the cartridge capable of being moved from the inoperative position towards the body first end under the injecting rod pressure; elastic means for automatically returning the cartridge towards the inoperative position when the pressure on the injecting rod is released, to cause a depression in the cartridge.