1998 Volume 40 Issue 4 Pages 232-240
The number of lingual cusp of the lower premolars were examined and compared with Circum-Pacific populations. The frequency of one lingual cusp was 54.9% and two lingual cusps was 41.5% on the first premolar in Japan. Mongols had a frequency of 68.1% for one lingual cusp, which was the highest among the groups examined when the frequency of one lingual cusp was compared in seven populations, followed by Japan (54.9%), Kiribati (51.9%), and Yami (44.1%). The frequencies of one cusp in South-Pacific groups were low in Samoa (36.2%), Fiji (37.4%) and Australian aboriginals (33.0%). The incidence of two lingual cusps on the first premolar were low in Mongols (29.8%), but South-Pacific groups, Samoa, Fiji, and Australian aboriginals, had incidences of about 50.0%. In the second premolars, all populations had more than 70.0% frequencies of two lingual cusps. The frequencies for three lingual cusps were more than 20.0% in Fiji and Australian aboriginals which were the highest among the groups studied.
The number of lingual cusps was more variable in the first premolar than in the second premolar. South-Pacific populations were characterized by high frequencies of lingual cusps in lower premolars.
