摘要：Doctoral dissertations are original results of studies presented to universities in fulfillment of doctoral degrees. They are thus papers of high quality. In America such dissertations are highly appreciated, whereas Japanese scholars and medical librarians have not yet recognized their value and utility. Nevertheless, doctoral candidates are under an obligation to publish their dissertations. Why are such academic materials not being paid attention to in Japan? In consideration of the above-mentioned fact, this paper reports on education in American dental universities, the American doctoral degree system in comparison with the Japanese one, and the methods of reference to dissertations. Furthermore, an analysis of American doctoral dissertations in dentistry belonging to the Nippon Dental University Library is presented together with research on the frequency of quotations from doctoral dissertations in major American dental journals, so as to determine the value of dissertations as a primary source.
