Dr. Robert C. Likins, 59, a dental researcher and an administrator at the National Institutes of Health and the National Institute of Dental Research from 1946 to 1968, died Thursday at St. James Hospital in Chicago Heights, Ill., following a stroke.

Dr. Likins, who was born in Springfield, Mo., earned his undergraduate degree at Kansas City University and his dental degree there in 1945. For the next year, he was a Carnegie Fellow in Dental Research at the University of Rochester School of Medicine and Dentistry at Rochester, N.Y.

In 1946, Dr. Likins was commissioned in the U.S. Public Health Service and began his career at NIH in Bethesda.As a researcher, he specialized in studies on the metabolism of flourides. At the time he left, he was head of the extramural programs of the National Institute of Dental Research.

Dr. Likins then became director of the Zoller Memorial Dental Clinic in Chicago, a post he held until his retirement last year.

Survivors include his wife, Gloria A., of Flossmoor, Ill., where the family lives, one son, David H., one daughter, Mary Fults, and one grandchild.

The family suggests that expressions of sympathy be in the form of contributions to the Brain Research Institute of the University of Chicago.