One of the most important events in dentistry history was the
discovery of local anesthetics in 1859 by Albert Niemann (1834
– 1861). In fact, this event represents the beginning of a new era
in dentistry. Despite the adverse and lethal effects of cocaine,
the first local anesthetic used in dentistry, this finding permitted
the develop of other local anesthetics with less adverse effects
and better safety index such as procaine, lidocaine, mepivacaine,
bupivacaine, prilocaine and more recently ropivacaine and
articaine. Local anesthetics constitute a group of elementary
drugs in the professional arsenal of dentistry and are the most
used drugs in this area. They act by preventing the conduction of
the nociceptive electrical impulses in a reversible way, generating
a loss of sensitivity to pain. Local anesthetics internally block Na+
voltage gated channels on neuronal fibers, thus decreasing nerve
conduction. Na+ voltage gated channels are complex structures
formed by two β subunits (β1 and β2) and a large α subunit in whose
central part is located the entry pore for this ion.
In the last 100 years, the reversible local anesthetic effect
added to the wide therapeutic index of these agents have allowed
to perform invasive procedures in the oral cavity in different areas
such as endodontics, oral and maxillofacial surgery, implantology,
restorative dentistry and periodontics without pain during
the performance of these treatments. This fact has meant an
unprecedented advance in the world history of dentistry.
Several research have been conducted and published with
the aim of improving the pharmacokinetic profile of these drugs
such as inclusion complexes with cyclodextrins and encapsulation
in liposomes and nanocapsules. These studies are aimed at
increasing the liposolubility of these drugs through the neuronal
cell membrane, as well as avoiding the use of vasoconstrictors that
are present in most local anesthetic formulations to counteract the
vasodilator effect of these drugs. Moreover, this new formulations
could reduce the side effects of this drugs, because these cell
carriers act as reservoir and from there they release (in a sustained
manner) the local anesthetics molecules. These latest advances
could allow in the near future the topical use of these agents and
limit the use of dental needles for their administration.
Recently, there has been special attention in relation to the
cytotoxic effects produced by local anesthetics. It has been shown,
for example, that these agents in low tissue concentrations (as used
in clinical practice) produce an induction of cellular apoptosis.
This fact could mean a possible coadjuvant treatment to the base
treatment of some types of cancer. Could it be that we are facing a
group of old drugs with a new target?