A preliminary study on inherited tooth morphology characters of Japanese and Chinese young adults--with special reference to the Carabelli tubercle.

Abstract

A comparative study on inherited tooth morphology characters, in particular the incidence of Carabelli tubercles in the maxillary dentition, was conducted on standardized stone casts obtained from 240 Japanese (124 males (male) and 116 females (females)) and 160 Chinese (74 male, 86 female) young adults. The following results were obtained: 1) No significant differences in the incidence of Carabelli tubercles according to sex or body height were found between the two groups. 2) However, significant differences in the incidence of Carabelli tubercles according to sex were found in both groups. The tubercles occurred more frequently in males. 3) Significant differences between the bilateral and unilateral occurrence of Carabelli tubercles were observed in both the Japanese (p < 0.05) and Chinese (p < 0.01) groups; Carabelli tubercles on upper first molars were always bilateral. 4) The highest incidence of Carabelli tubercles was found in individuals with a body height of 166 approximately 175 cm in both groups, and a significant difference (p < 0.05) between the 156 approximately 165 cm and 166 approximately 175 cm groups was particularly evident in the Japanese adults. The authors postulate that bilateral occurrence of Carabelli tubercles was originally an inherited character in the molar region, but that the character was inhibited during the process of evolution of the masticatory system and regression of the molar dentition.