Abstract: The present invention relates to improvements in syringes for injecting pasty products, wherein the end of the body thereof comprises a screwed stopper provided with a groove and an oblique channel in the outer opening of which is fixed the endpiece of a needle. To clean the syringe, the stopper is unscrewed and the residue, contained in one piece in the groove and in the channel, is extracted. The present invention is more particularly applicable in dentistry.