Samuel W. Dennis was born on October 16, 1836 in Litchfield, Maine, and began his professional life as a dentist in 1860. After a short time in dental practice, he earned the M.D degree from the University of Pennsylvania in 1870 and spent the remainder of his career focusing on dental surgery. A practitioner with a national reputation, in 1871 he was elected president of the American Dental Association, and in 1877 he received an honorary D.D.S. from the Indiana State Dental College. In 1881 he became a Fellow of the Royal Microscopical Society of London. At the state and local level he became President of the California State Odontological Society and the San Francisco Dental Association. In addition to his activities in the UC College of Dentistry, he was a leader in the California State Dental Association, and drafted legislation regulating the practice of dentistry in California. He also served on the first California State Board of Dental Examiners in 1885.

With dual training as both an M.D. and D.D.S., Dr. Dennis was an advocate of concurrent training in scientific subjects for dental and medical students. There had been unsuccessful attempt to found a dental school in San Francisco in the 1870s, but Dr. Dennis persisted, corresponding with eastern colleagues at Penn and Harvard to plan an optimal dental school for the West. He worked closely with the UC Medical Department to develop a dental school in association with the University of California, and by 1881 the medical faculty presented an appeal to the Regents to establish such a school, stating that, “Dentistry is an important collateral branch of medical science…and dental education is necessary for the public good.” With the support of the medical faculty and the promise of shared instructional space in the Toland Medical Building, the Regents approved the request and the first class of twenty-six students matriculated in 1882. Six of seven members of this first faculty held M.D. degrees and only two held the degree of D.D.S., a fact which reflects the close alliance of dentistry and medicine in the nineteenth century. S. W. Dennis served as Dean of the UC College of Dentistry during its first year (1881-1882), and also from 1883-1885. During this time dental instruction was closely allied with the medical curriculum and both lecture and clinical training took place in the Toland Medical Building.

In 1896 Dr. Dennis severed his connection with the College of Dentistry in the midst of a debate with “more progressive faculty” over proper dental curriculum. He died of pneumonia at the age of seventy, on January 20, 1907.