Dr. A. Harry Ostrow, 80, who as director of the D.C. Bureau of Dental Health was given credit for the fluoridation of Washington's water supply in 1952, died Jan. 2 of a stroke at the Bethesda Retirement and Nursing Home.

Dr. Ostrow, who also had a private dental practice in Washington, was named the city's first director of the Bureau of Dental Health in 1939. He held that job until he retired in 1965.

He was born in Bridgeport, Conn., and had been a resident of Washington since 1917. He was a graduate of the old Central High School, George Washington University and the University of Maryland Dental School. He held a degree in public health from the University of North Carolina.

Dr. Ostrow opened his dental practice in Washington shortly after graduating from dental school in 1928, and he went to work for the D.C. Department of Health in 1930.

He was an early advocate of the fluoridation of municipal water supplies as a means of preventing tooth decay, and he lectured widely on that and on other issues involving dental health. Shortly before he retired, he announced results of a study that showed a 60 percent reduction in cavities in the teeth of Washington schoolchildren in the 12 years since the city's water had been treated with fluoride.

In 1959 he was the first recipient of the D.C. Dental Society's outstanding dentist award. He was a founder of the American Association of Public Health Dentists, honorary past president of the State and Territorial Dental Directors Association and a fellow of the American College of Dentists.

Dr. Ostrow also was a trustee of the D.C. chapter of the American Cancer Society, a past president of Argo Lodge of B'nai B'rith, a member of the Association of Oldest Inhabitants, a 32nd degree Mason and a past master of Benjamin Franklin Lodge and a member of Almas Temple of the Shrine. He also was a past president of Indian Spring Country Club.

Survivors include his wife, Mildred, of Washington; a daughter, Abbe Miller of Cincinnati; a son, Dr. Morton, of Potomac; three grandchildren, and one great-grandchild.