John C. Chao, DDS, MAGD

Research Associate Professor, Post Graduate Program in Periodontics, SUNY – Buffalo (University at Buffalo)
Anxiety Management, Faculty, USC School of Dentistry

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John C. Chao, D.D.S., M.A.G.D
Anxiety Management,
Behavior Science,
Faculty, USC School of Dentistry

From Chili Peppers Comes Anesthetic That Blocks Pain But Induce No Numbness

Imagine going for your dental visit and there's a "novacaine" gives you a painless experience, while at the same time you feel no numbness, wooziness, slurred speech or loss of control of your mouth. This new local anesthetic is being developed by a group at Mass. General from ingredients that include "capsaicin," which imparts "hot" to chili peppers.

This research work, described in the scientific journal Nature, using a rat model, breaks from the standard approach to local anesthesia which involves anesthetizing all neurons, not just the pain neurons. Since this new anesthetic only block out pain neurons, no other sensation is affected. Thus, sensations of touch and mobility are not diminished and the patient does not experience facial paralysis, speech problems, accidental tongue or cheek biting or other disabling symptoms associated with the "novacaine" injection.

"It's a really clever piece of work, based on one of those 'I wish I'd thought of that' ideas," said Dr. Stephen G. Waxman, head of the department of neurology at Yale University's School of Medicine. "This is an important piece of research." Capsaicin generates the heat that allows a particular kind of "lidocaine" to penetrate into the pain neuron. However, this lidocaine, called QX-314, does not ordinarily penetrate cell membranes and in fact was deemed useless when it was invented in the l940's. Capsaicin selectively makes pain neuron permeable to this otherwise impotent anesthetic. But since this lidocaine in the form of QX-314 can only penetrate pain neurons, no other sensation is blocked. Therefore there is no numbness, yet no pain.

At this time, there is no indication as to when this exciting anesthetic will be available to dentistry.

However, even now there is a way to numb only the tooth that needs treatment, without causing numbness in the surrounding tissue. It is called "intraligamental anesthesia." A local anesthetic is introduced into the space between the root of the tooth and the bone. This space contains the ligaments that attach the root to the bone. The anesthetic is made to seep to the tip of the root of the tooth and numb the nerve where it exits the root. Thus, even though the tooth is numbed, the rest of the mouth is not.

There is some minimal discomfort because of the pressure needed to induce the anesthetic to flow to the tip of the root. However this low level of discomfort can be further minimized by the use of a new extra-strength topical anesthetic (Oraquix) that can be applied to the area prior to injection. Ask your dentist about "intraligamental anesthesia" if you do not prefer the numb sensation in the mouth.


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