After a synthetis of the main infectious illness transmittable through the oral cavity, the authors describe the experimental use of a new disposable syringe in dentistry. On the basis of a total of 160 local injections for dental interventions, the authors can say that this instrument allows to operate with a maximum of safety for the absolute absence of a direct infection, also by the simple salivary mean, between patients. More advantage come from the risk drop of needle puncture for the dentist and the assistants and for the automatic autoaspiration the syringe is provided which.