Molar Cusps in Southern Chinese

Abstract

Aim: To investigate the number of molar cusps of the Southern Chinese and compare these with studies in dif- ferent populations. Materials and Methods: The number of molar cusps of study casts of an unselected sample from a 12 year old Hong Kong Oral Health Survey of 12 year old children (n=459; 295 boys and 164 girls) were studied. Results: For upper first molars, 5-cusp molars were the most prevalent in males (39%) while 4-cusp molars were the most prevalent in females (39%). For lower first molars, 5-cusp molars were the most prevalent in both sexes (63%-72%). For lower second molars, 5-cusp molars were the most prevalent in both sexes (43%-53%). Conclusion: Different from traditionally described, the Southern Chinese has more 5-cusp lower second molars than the 4- cusp ones. In modern man, the number of cusps of the upper molars is frequently reduced from four to three. The formula for the number of cusps of the upper molar series is changing from 4-4-4 to 4-4-3 and 4-3-3. The trend is more marked in fe- males than in males of all populations that have been stud- ied. In most studies, males generally showed a lesser ten- dency than females to reduction in the number of cusps of the upper molars. The process of reduction occurs through the elimination of the hypocone or distolingual cusp, with a subsequent decrease in the mesiodistal crown diameter and in the occlusal area.