Xylocaine: 50 years of clinical service to dentistry.

In today's dental practice, local anesthesia is safe and effective, and injectable agents only rarely cause allergy. Ester-type agents, like procaine, which served the profession for over 50 years, have now been abandoned and are no longer available in dental cartridges in the U.S. Modern practitioners know of their disadvantages only through historical accounts of local anesthesia, and utilize daily the excellent chemical and pharmacologic characteristics of the amide local anesthetics, a tradition begun with the introduction of Xylocaine in the late 1940s and a tradition which will likely continue into the 21st century. The reader is referred to Table III for a comparison of quantities and dollar-value of sales of amide local anesthetics available in dental cartridges (17). In order to supplant Xylocaine (lidocaine) as a preferred local anesthetic in dentistry, any new agent will have to prove that it is superior in terms of short onset, appropriate duration, stability, excellent safety record, low allergenicity, and topical efficacy. As our understanding of the molecular structure of ion channels and the interactions of local anesthetics with neural sodium channels increase, new agents can be developed rationally. In the meantime, the amide local anesthetics will continue to serve dentists and their patients by providing safe and effective control of pain to facilitate ever-advancing surgical and restorative techniques.

Xylocain (lidocaine, lignocaine), its discovery and Gordh's contribution to its clinical use.

Hans v. Euler, while investigating how genes and enzymes were chemically related in some chlorofylldefective mutants of barley, isolated gramine, an indole. Erdtman synthetized isogramine and found it to have weak anesthetic properties. He then together with Löfgren synthetized other amino-amides, but no one of them could compete with the existing local anesthetics of the ester-type, derivatives of para-aminobenzoic acid, e.g. procaine. Later Löfgren and Lundqvist followed up these studies and found an amid compound lidocaine (2-dimethylaminoacet-2, 6-xylidide). Lidocaine represented such a significant advance over procaine in clinical tests preformed by T. Gordh that it was introduced for clinical use. It has now during a half century been the standard local anesthetic drug. All local anesthetics are neurotoxic in high enough doses. Xylocain, however, has had an excellent record of safety. Only during the last years have there been reports on possible toxic irritation and damage by Xylocain used for spinal anesthesia. The aetiology is still not clear In this connection two early observations by Gordh and his coworkers are discussed.

Local anesthetics: dentistry's most important drugs.

One hundred and fifty years ago, Horace Wells opened the door to local anesthetics. Since then, many advances have been made in pain control. The development of dentistry's most important drugs is highlighted here.

The use of intravenous anesthesia and sedation techniques in oral and maxillofacial surgery.

In 1943, Olson described a method for administration of thiopental for anesthesia during oral surgical procedures (J Oral Surg 1:197, 1943). Patients were instructed not to eat for 4 hours before the scheduled surgery and to bring an escort. Premedication with atropine or morphine was not routinely used. Following venipuncture, a 2- to 3-mL test dose of thiopental (Pentothal, Abbott Laboratories, North Chicago, IL) was injected. After a pause of 15 to 20 seconds, 6 mL was injected slowly over 40 to 50 seconds. Additional medication was titrated slowly in intermittent doses to maintain an adequate level of anesthesia. The mouth was packed and kept meticulously dry to prevent coughing or laryngospasm. The patient's color and respiration were continually observed and the airway maintained. Initially, a 5% solution was used by Olson; later it was changed to 2%. Use of this concentration made it easier to titrate to "upper levels" of anesthesia because profound depth was not required. Also, adverse effects (eg, coughing, laryngospasm) occurred less frequently, and there was less venous irritation with the 2% solution. Based on his experience of 8,203 cases, Olson claimed that most patients tolerated the anesthetic well, but he recommended avoiding this technique for children younger than 12 years of age.

Looking back and looking forward.

'Forty years back and forty years on' was the title of the address given by Francis Manfield at the annual meeting of the RCS of England in December 1970. Francis, twice president of the Middx & Herts Branch, which this year celebrates its first 40 years, started in practice in 1930, so he was well qualified to look back over those 40 years. The aspects of change in dentistry, 1930-1970, make arresting reading more than 20 years later. His predictions for the future are equally interesting.