Aspiration,before and during the injection of anaesthetic,is strongly recommended the conventional literature of dental surgery.The development of passive systems witch depend on a (semi automatic) backward movement of the components of the cartridge made easier the process of aspiration.A well-balanced syringe which suits comfortably to the hands gives to the dentist good tactiles information transferred from the tip of the needle to the finger grip of the syringe.This should be associated with user-friendly aspiration.This two elements must be the reason of the choice of an Injection instrument
