Carbocaine, Xilocaine, Articaine are some of the used substances.
The most used kind of syringe is the
one designed for ampoules, and it simply is a steel device that is
sterilyzed after each patient, into which an ampoule and a needle (both
disposable) can be inserted.
also are some special kinds of syringe, like for example the one used
to do the so called intra-ligamental anesthesia: in this kind of device,
the ampoule is closed in a sealed tube that avoids scattering of glass
pieces in case the ampoule should break, since the pressure used for
this kind of injection is higher.
For all the teeth belonging to the maxilla (upper jaw), plexic
anesthesia is performed. It simply consists in delivering the substance
"under the skin", within the mucosa that is, more or less at the
presumed height of the root's apex of the tooth to be treated.
same anesthesia can be used in the incisives of the mandibula (lower
jaw), but offers increasing problems when it is performed on more
posterior teeth: the reason is that the mandibular bone covering the
teeth, increases its thickness towards the rear part, at the point that a
plexic anesthesia on a lower molar could have a weak result.
operators prefer to do a troncular anesthesia instead. It's an
injection on the lower alveolar nerve, controlling sensitivity on all
the mandibula (one for the left and one for the right side). A mucosal
area situated posteriorly to the last molar, almost next to the pharynx'
opening is pinched.
The effect is slightly retarded and
causes the anesthesia of all the mandibular side up to the lower lip's
half, and also of the same half of the tongue (because of the proximity
of the lingual nerve).
Whatever the anesthesia
being used, its effect may last from 1 hour to over 4, according to the
situation. The substance is being disposed along with the urine, doesn't
leave any trace in the body and does not produce any collateral effect
nor any addiction.