Dr. Fu is China's first orthodontist to continue his studies in America, attending Northwestern University in 1981-82.

In a clear sign that orthodontics has been given a push, the Government has allocated money for expensive X-ray machines and other large dental equipment that had to be imported. It has also financed a factory to make braces.

This investment has vastly reduced the costs of Chinese braces. One stainless steel tooth bracket now costs 50 cents to make in China. Although the quality is not as high as it is in the United States, orthodontists in Hong Kong are considering buying the cheap tooth brackets.

The cost for a complete program of braces in China is $100, which may be just a fraction of the cost in America, but it represents the equivalent of three to four months' salary for an average Chinese worker.

Comparison With U.S. [ The American Association of Orthodontics, which is based in St. Louis, said the cost of braces and treatment varies considerably in the United States, according to severity of the problem and how well the patient cooperates. But it said ''typical braces'' usually cost from $3,000 to $5,000. The association also estimated that there are roughly 10,000 orthodontists in the United States. That means a mere 24,000 mouths for each specialist. ] In Beijing, there are two major dental hospitals, but only about 40 orthodontists. Each year, Dr. Fu and his staff of 37 orthodontists and assistants at the Dental School of Medical Sciences University of Beijing accepts just 700 new walk-in patients, about all his offices can handle. Registration takes place just once each year on a first-come, first-served basis.

This March, before the day of registration, hundreds of parents accompanying children with crooked teeth camped for two days and nights outside the university's hospital.

''My parents brought me here,'' said Sun Yingchu, a 14-year-old patient at Dr. Fu's clinic. She spoke through a wiry night brace that seemed to envelop her face.