Maryland dentists are being warned by the State Health Department that they risk getting hepatitis if they do dental work on Indochinese refugees who have not been tested for the disease.

Twelve percent of the refugees have been shown to be long-term carriers of the hepatitis virus, according to a study done in Canada, while only three-tenths of a percent of the American population is so infected.

The refugee carriers present no real risk to the general public, according to the federal Center for Disease Control in Atlanta.

But they do to dentists, who come in contact with the refugees' blood and saliva while filling their teeth, said Dr. Philip H. Pushkin, director of dentistry for Baltimore County.

The hepatitis virus is often transmitted through contact with blood and saliva and dentists run a high risk of hepatitis exposure even in the best of times while dealing with the largely healthy American public.

The risk is so high that research has shown one dentist in every four will contract the disease sometime during his medical career, according to Dr. Mark Kane, an epidemiologist with the federal Center for Disease Control's hepatitis laboratory in Phoenix, Ariz.

Kane said other research has confirmed the Canadian estimate that 12 to 13 percent of the Indochinese refugees carry hepatitis, and said the dental health status of most of the refugees is also "very poor."

Pushkin said refugees with severe tooth decay have been flocking to public health clinics in Maryland.

"When they hit this county" where they become eligible for federal health insurance programs, he said, "the first they do is ask for a dental appointment."

Pushkin told the board of governors of the Maryland State Dental Association yesterday that dentists should refuse to treat refugees until they have had a blood test for hepatitis.

If the tests show any refugee to be a carrier, the dentist should wear a mask, gloves and glasses while treating him, and sterilize all equipment afterward, Pushkin said.

The state Department of Health and Mental Hygiene plans to send a letter warning all dentists in Maryland, and Pushkin's suggestions have benn put into practice by public health dentists in Baltimore County.

Although people who contact hepatitis usually recover completely, statistics show that 5 to 10 percent become carriers. And if the dentist himself becomes a carrier, his career may be over. "For my profession, it's a killer," Pushkin said.

Hepatitis B, the type carried by some of the refugees, is a contagious disease transmitted by blood and other body fluids. Two or three months after a person is exposed, it can produce such symptoms as loss of appetite, stomach pain, vomiting, and often jaundice and fever.

One-third of hepatitis patients have only mild symptoms, and another one-third may never even know they have it.

Kane estimated that one-third suffer jaundice and liver problems, and of these a small percentage have long lasting liver damage and may die.

Kane said dentists and oral surgeons have long been known to have an increased risk of hepatitis, along with surgeons, blood technicians and other health workers exposed to blood products. Drug addicts and patients on kidney dialysis also have high hepatitis rates.

Kane said about 1 percent of dentists and oral surgeons are carriers. This does not mean all of them transmit the disease, but those dentists who do are usually forced to stop practicing, either because they lose their state licenses or cannot get insurance, he said.

The high carrier rate among the refugees means that vitually all of them have had hepatitis, Kane said. Medical screening in the refugee camps does not include a blood test for hepatitis, although the CDC recommends that regugees receive the test as part of a checkup once they arrive in this country. The CDC is studying the carrier rate, but there are no facilities in the camps to do mass testing for hepatitis now, said Brian Dugan, foreign coordinator for the CDE's Indochinese refugee program.

There has been no move so far to require hepatitis tests for Indochinese refugees who receive dental treatment in the District of Columbia and Virginia, according to dental health officials there. They said they had not been made aware that the hepatitis carrier rate was a problem among the refugees.