Royal Dental Hospital OSSA – Old Staff and Students Association. The Royal Dental Hospital Old Students and Staff Association (RDH OSSA) was founded, as a registered charity, in 1967. It is believed to be the only dental alumni association that extended membership to staff members who were not professionally qualified. With the closure of the Royal Dental Hospital in 1985, the source of new members ceased. However, and despite falling numbers, RDH OSSA continues as an active alumnus association. Following the closure of the Royal Dental Hospital, its building in Leicester Square still stands in the guise of the Hampshire Hotel. So that guests of the hotel should be aware of the building’s former life, members of RDH OSSA commissioned a plaque, which was placed in the hotel lobby at the time of the Hampshire Hotel opening, to mark the history of the Royal Dental Hospital and School of Dental Surgery. RDH OSSA ceased to be a registered charity in 2008, but members still meet for annual reunion lunches in the Hampshire Hotel. OSSA members have very recently raised funds for a Westminster Green Plaque to be placed on the outside of the Hampshire Hotel to record that the Royal Dental Hospital stood on that site from 1901 to 1985.