* More than 100,000 dental hygienists practice in the United States, the American Dental Hygienists' Assn. says.
* Dental hygienists must first graduate from at least a two-year dental hygienist program accredited by the American Dental Assn. There are 230 such programs in the country.
They must pass a written national exam and a clinical exam given by a state or regional board and then be licensed by the state. Continuing education requirements vary by state.
* Average pay is $22.20 an hour nationwide, according to a 1996 American Dental Assn. survey, the latest figures available. But the pay in major metropolitan areas such as Los Angeles can often run considerably higher, dentists report.
* For more information, write to the American Dental Hygienists' Assn., Division of Professional Development, 444 N. Michigan Ave., Suite 3400, Chicago, IL 60611, or call (312) 440-8930.