Dental anesthetics are manufactured to be acidic, so that they have a long shelf life. This is needed so that epinephrine does not degrade. However, an acidic injection causes a stinging effect as well as mild tissue damage (think lemon on a wound). Anesthetics only start getting the tissues numb when the body neutralizes the acidity. This is why dental anesthetics sometimes take a while to take full effect. Buffering the anesthetic with 8.4% sodium bicarbonate causes more of the active form of anesthetic to be available right away, which results in a considerably quicker time for the numbing effect to take place.
FAQ’S
Generally speaking – yes. Only allergic reactions to the anesthetic is the absolute contraindication for it. However, some anesthetic agents or techniques should be avoided or used with caution in certain individuals. This is why is important that the patient inform the doctor about any changes in their health, so that the doctor can decided individually the best treatments options.
The onset of anesthesia depends on a series of reasons. Some of them are: anatomical variations from patient to patient, local infection or inflammation, patient anxiety etc.
Modern anesthetics are safer comparing to the ones used a few decades ago. Allergic reactions are very very rare, ranging between 0.1% – 1% chances of developing an allergic reaction. And even then, in the majority of cases the reaction is to the preservatives from the anesthetic, and not to the anesthetic itself.