The Japanese introduction of dentistry into Korea was for treating the Japanese residing in Korea Noda-Oji was the first Japanese dentist for Japanese people in Korea in 1893, and Narajaki doyoyo, an invited dentist was posted in the Korean headquarter of Japanese army in September, 1905. The imperialist Japan licensed the dental technicians (yipchisa) without limit and controlled them generously so they could practice dentistry freely. This measure was contrary to that in Japan. (In Japan no new dental technician was licensed.) Komori, a dental technician opened his laboratory at Chungmuro in 1902. The dental technician had outnumbered by 1920. In 1907, the first Korean dental technician Sung-Ryong Choi practiced dentistry in Jongno. The imperialist Japan made the regulations for dental technicians to set a limit to the advertisement and medical practice of dental technicians. The first Korean dentists Suk-Tae Ham was register No. 1 in the dentist license. The Kyungsung dental school was established by Nagira Dasoni for the purpose of educating some Korean people that contributed to Japanese colonization. It made progress with the help of Japan, it was was given the approval of the establishment of the professional school in January the 25th, 1929. It was intended to produce Korean dentists in the first place but became the school for Japanese students later on. The association of Chosun dentist, which had been founded by Narajaki doyoyo, was managed by Japanese dentists in favor of the colonial ruling. The Hansung Association of Dentists established in 1925 was the organization made by the necessity of the association for Koreans only. The Japanese forcefully annexed the Association of Hansung Dentists (Koreans only) to the Association of Kyungsung Dentists to avoid collective actions of Korean dentists in the name of 'Naesunilche' -- 'Japan and Korea and one'. Their invading intention was shown in the event of 'decayed tooth preventive day'. Japanese controlled the gold for dental treatment by licensing and limited the stuff for dental treatment by rationing. The association of Chosun dentists was a group organized for the academic purpose by Nagira Dasoni and etc. In October of 191, where as the association of Kyungsung dentists was constructed on the background of Nagira Dasoni. This establishment of the association of Kyungsung dentists represented a backlash against Ikuda singjo having a complete control over the association of Chosun dentists. The number of Koreans who wrote to the Chosun Dental Science Academy was 27, and they wrote 75 articles, which amounted to 15% of 486 articles. The number of Koreans who wrote to the Kyungsung Dental Science Academy was 16, and they wrote 52 articles, which amounted to 11% of 481 articles. These had been a lot of improvement by activity backlash of the dental association. However, they experimented Korean people. The experiments included the experimental stimulation of dental pain by Nagira Dasoni, use of toxic agents on human bodies such as mercury, bismuth and carcinogenic benzole, and experimental treatments with a poor prognosis. Worst of all, the rapid discrimination was stressed. The different dentition according to races was the subject of comparison researches. The dangerous chemicals were sometimes used. The non-akaloid medication was investigated to relieve the dental pain but, the habitual side effects were not unusual by the overuse of morphine or heroin, which was known to be irrelevant due to their habitual side effect. The use of new and unproven material was recommended as well. Especially, the alloy that substituted gold, attracting attention, was substantiated by researches.