People may soon be able to choose which form of dental anesthesia they prefer: injection or electric current.

A new form of electronic anesthesia that patients control as they sit in the dentist's chair is being tested in California and elsewhere, and researchers say it may eventually replace the need for traditional Novocain injections.

Electronic dental anesthesia (EDA) sends electronic impulses to the brain through electrodes attached to the gums. The impulses block pain signals traveling from nerve endings in the teeth to the brain. Patients can control the level of anesthesia from a box by their chair.

The anesthesia causes a tingling, vibrating sensation that stops when the machine is turned off. There is no numbing feeling or slurred speech that typically follow injections.

Studies done at the University of Southern California School of Dentistry in Los Angeles show that EDA is successful in controlling pain in 80 percent to 95 percent of the cases. It has successfully replaced injections for fillings, bridges, bonding and cosmetic procedures, said Dr. Charles E. Joseph, assistant professor of the Department of Periodontology at the USC School of Dentistry.

About 1,200 dentists, out of 120,000 nationwide, now use EDA. Some patients find the electronic sensation uncomfortable and still prefer traditional anesthesia.

"People who are not good candidates for this are people who have phobias about electronics, who don't like to try new things or who are incapacitated in some manner where they can't control the box," Joseph said.

EDA was first introduced in 1985, and Joseph predicts the majority of dentists will be using it in the next five years.