From the fertile minds of dentists....
Ring
M E
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School of Dental Medicine, State University of New York, USA.
D003815:Dentists / Q000266:history*; D004867:Equipment Design / Q000266:history; D049672:History, 19th Century; D049673:History, 20th Century; D010330:Patents as Topic; D013672:Technology / Q000266:history*; D014481:United States