Morphological analysis of the occlusal surface of maxillary molars in Koreans

• We examined dimensional differences of maxillary molars.
• Sexual differences in maxillary molars were more prominent in M1 than in M2.
• Hypocone reduction had an inverse relation to cusp area of the protocone.
• Protocone is suggested as a reliable parameter for comparing differences in maxillary molars.

ObjectiveTo determine the diameter of the crown, total crown area, individual cusp area, and occlusal table area in Korean maxillary permanent molars, as well as dental characteristics relevant to the hypocone reduction trait.Materials and methodsSubjects included 121 dental school students in Korea (81 men and 40 women). A digital image analysis system was used for measurements and we relied on visual scoring to assign categories of hypocone expression.ResultsThe mean crown dimension was larger in the first molar (M1) than in the second molar (M2). Regarding differences according to gender, the crown diameter, total crown area, and individual cusp area were significantly larger in the men than in the women. The mean occlusal table area ratios were 61% for M1 and 57% for M2, and these ratios increased in proportion to the total crown area. With respect to the hypocone and other features of the maxillary molars, differences between the men and women were more prominent for M1 than for M2. The M2 hypocone tended to be smaller than the M1 hypocone, and hypocone reduction was inversely related to the cusp area of the protocone. The protocone area may be considered a reliable parameter for comparing race and/or gender differences in maxillary molars.ConclusionThis study concerning characteristics of the maxillary molar occlusal surface in Koreans provides useful information for comparative studies among human races.