An aspirating hypodermic syringe and method for injecting dental anesthetic in which anesthetic flow through the needle is established independently of the fingers of the operator and in which different rates of flow are provided, including positive flow while the needle is entering the tissue. Effective...http://www.google.fr/patents/US5180371?utm_source=gb-gplus-shareBrevet US5180371 - Hypodermic anesthetic injection apparatus and method
Hypodermic anesthetic injection apparatus and method
