His uncle and aunt were well-known dentists in Tokyo, and young Shinjiro Takahashi became interested in dentistry. Shinjiro Takahashi entered Nippon Dental College in 1914 and graduated in 1919. In addition to studying dentistry, he worked hard to teach himself English.
He decided to go to the United States and was accepted at the University of Pennsylvania as a third-year dental student. After graduation (1924) from dental school, he entered the orthodontic graduate course (1937) under Doctor Johnson, who had just moved from the University of Michigan.
In October 1925, Shinjiro Takahashi returned to Japan and resumed his work at the hospital.
In 1929, Takahashi became a lecturer at the Tokyo National Dental School, a former hospital for National License Examination. He was appointed professor at Tokyo Dental College (1937) and then professor at Tokyo Dental University (1949) and the following year took an additional post as lecturer at Tokyo University.
During War (in 1937, and especially from 1943 to 1945,) orthodontic activity in Japan slowed. Takahashi was asked to participate as an interpreter in many political negotiations with GHQ.
When he retired from the university in 1962, he opened an orthodontic clinic, the first private orthodontic clinic in Japan.
He believed strongly that general dentists needed to open their eyes to see the importance of orthodontics in dental practice. He offered postgraduate orthodontic courses for general practitioners, and this helped to increase the demand for orthodontic treatment in Japanese society.