The first synthetic anesthetic was procaine and it is most commonly known as Novocain. Novocain had its encountered difficulties because of its properties which caused the anesthetic to diminish rapidly and its effect was minimal. The structure of Novocain is an ester, which is capable of causing allergic reactions. Novocain contains an enzyme that can be converted into para-aminobenzoic acid which is recognized as an allergen.
The modern local anesthetic which is now widely used is the injectable anesthetic Lidocaine, which uses hypoallergenic amide molecular structures. Lidocaine also contains a miniscule amount of epinephrine which is adrenalin. This chemical, epinephrine, provides extensive anesthesia for hours but as a repercussion causes vasodilation. Vasodilation is the relaxation of smooth muscle cells in the vessel walls causing blood vessels to widen. The dilation of blood vessels leads to a decrease in blood pressure and in order to control this vasoconstrictor must be used. The reason lidocaine is mixed with a low concentration of epinephrine is to function as a vasoconstrictor, closing the blood vessels down to keep the longevity of numbness.
Any past history of an allergic reaction to any of these anesthetics should always be brought to the attention of the doctor administering the medication. Typically these available anesthetics work for everyone but every one out of one-hundred will experience some type of adverse effect and will need to discuss with their doctor what their other options are for anesthetics. Our doctors at 7 Day Dental are here to answer your questions.