Sexual Dimorphism in the Tooth Crown Dimensions of the Second Deciduous and First Permanent Molars of Taiwan Chinese

Abstract

Summary: Sexual dimorphism in the crown components in the second deciduous molar (dm2) and the first permanent molar (M1) of the dental casts taken from Chinese living in Kaohsiung (Taiwan) was investigated. Mesiodistal and buccolingual crown diameters, and 4 main-cusp sizes in the maxillary molars and mesiodistal diameters of the trigonid and talonid in the mandibular molars were measured using a digital caliper (0.01 mm). Percentage sexual differences were calculated. With the exception of trigonid mesiodistal diameters, the mean values of males were larger than females. In both of dm2 and M1 the mean values of the trigonid mesiodistal diameters were slightly larger in females than in males, but the differences were not significant. Percentage sexual dimorphism was smaller in the mesiodistal diameters than in the buccolingual in both dm2 and M1. The crown components showed larger sexual difference in dm2 than in M1, while in the maxilla the external crown size showed larger sexual difference in M1 than in dm2. The buccal cusps showed larger sexual difference than the lingual in the maxillary molars and the talonid showed larger sexual difference than the trigonid in the mandibular. Sexual dimorphism of dm2 and M1 in their crown components displayed similar pattern, although the different degree was noted. This result is thought to relate to the fact these molars belong to the first dentition embryologically.The second deciduous molar (dm2) morphologically resembles the first permanent molar (M1). These two molars adjoin among the molar series, and they belong to the first dentition embryologically. They have similar crown shapes and occlusal groove-patterns, but different sizes. Although there are many similarities between them, they are not identical.The maxillary molar teeth have 4 main-cusps; paracone, metacone, protocone and hypocone. The mandibular molar teeth consist of the mesial trigonid and the distal talonid. Thus the maxillary and mandibular molar tooth crown consists of several crown components, and the crown shape can be expressed by these crown components (Yamada et al

Sexual dimorphism in deciduous crown traits of a European derived Australian sample

“…This information is not captured by overall crown size and highlights the information gained from the trigonid and talonid measurements. The level of dimorphism in the trigonid is nearly twice previous reports from the deciduous dentition [29,31]. Also the talonid has commonly displayed greater dimorphism than the trigonid [29,31].…”

“…The few studies of sexual dimorphism in the size of the trigonid and talonid in the deciduous dentition have shown greater differences than crown size. The talonid has been found to be 7.15% larger in males than females in studies of Australian Aboriginals [31] and Taiwanese Chinese [29,31]. The higher sexual dimorphism in the talonid compared to the trigonid has been attributed to its later development than the trigonid, resulting in greater exposure of the talonid to hormones during development [31].…”

“…The trigonid and talonid are the mesial and distal portions of the mandibular molars, respectively [29,30] (Fig. 1).…”

Sexual Dimorphism in Mesiodistal and Bucolingual Tooth Dimensions in Chilean People

“…The presence of sexual dimorphism in the size of the temporary and permanent teeth is a fact welldocumented in humans and primates (Garn et al, 1967;Garn et al, 1977;Scott & Turner, 1997;Kondo et al, 1998;Kondo et al, 2005;TeschlerNicola, 1992;Wood et al, 1991).…”

“…Most studies indicate that the mandibule canine is the tooth that presents greater dimorphism, followed by the first and second maxillary molars (Acharya & Mainali, 2007;Kondo et al, 1998;Kondo et al, 2005;Ling & Wong, 2006). In our work, the significant differences were found mainly in bucolingual diameters, but theyincluded various teeth of all dental groups, the largest being found in teeth 4.4 and 4.7, these results are similar to those reported by Ruiz in a Chilean population similar to this study, which reinforces the arguments (Alt et al, 1998) that changes in dental dimensions are influenced by ethnic factors.…”