抄録
The mongolism was first reported as Down's syndrome in 1866 [1]. Later research findings by Lejeune [2], Böök [3] in 1959, Ford [4] in 1959 and Jacob [5] in 1959, established the etiology of mongolism as due to the abnormality of chromosomes. From a dental point of view, Brown [6], Benda [7], Dow [8], Cohen [9], and Johnson [10] have made contributions respectively. According to these investigators, high incidence of periodontal disturbances and low caries prevalence can be deemed as the characteristics of this hereditary malady. Brown [6] also observed a congenital missing of one or two teeth in high frequency. It is, however, very seldom that we find an investigation of this kind in dental realm in the domestic publication.
Recently, we encountered a case of mongolism which presented a congenital missing of lower deciduous lateral incisors bilaterally and, at the same time, a supernumerary tooth existed in the region between upper left central and lateral incisors.
