Pergamon Archs oral Biol. Vol. 41, No. 7, pp. 641 645, 1996 Copyright © 1996ElsevierScienceLtd. All rights reserved Printed in Great Britain PII: S0003-9969(96)00066-0 0003-9969/96$15.00+ 0.130 MESIODISTAL CROWN DIAMETERS OF PERMANENT TEETH IN JORDANIANS F. N. HATTAB, ~'* S. AL-KHATEEW and I. SULTAN 2 aDepartments of Restorative and Pediatric Dentistry, Faculty of Dentistry, Jordan University of Science and Technology, Irbid, Jordan and 2Department of Orthodontics, Faculty of Dentistry, Jordan University of Science and Technology, Irbid, Jordan (Accepted 17 June 1996) Summary--Mesiodistal crown diameters were measured from dental casts of the permanent teeth of 198 Jordanians (86 males and 112 females), aged 13.4-19.1 years. The differences in the crown diam- eters between the right- and left-hand sides of the dental arch were not significant, suggesting that either right- or left-side measurements could be taken to represent the tooth size of the study population. Males had significantly larger teeth than females, ranging from p < 0.05 for the incisors to p < 0.001 for the first molars. In both sexes, the maxillary lateral incisors showed the greatest variability [coeffi- cient of variation (CV) 8.8%] and the first molar the least (CV 5.8%) in mesiodistal diameter. Canines displayed greater sexual dimorphism in crown size than any other tooth class. The cumulative tooth widths of males exceeded those of females by a sum of 3.1 mm in the maxilla and 3.6 mm in the mand- ible. These differences were statistically significant (p < 0.01). Comparisons of the mesiodistal crown di- ameters between population groups showed that Jordanians have tooth sizes close to those of Iraqis, but significantly larger than those of Yemenite-Jews, Caucasians and Chinese. Copyright © 1996 Else- vier Science Ltd. Key words: permanent dentition, tooth size, Jordanians. Mesiodistal crown diameter, also called tooth size, tooth crown size, or tooth width, provides signifi- cant information on human evolution and biological problems as well as in forensic and clinical odontol- ogy. Evolutionary anthropologists use mesiodistal diameter to trace the reduction of tooth size that appears to be a concomitant of selective forces, technological and dietary changes during human evolution (Bermudez de Castro and Nicolas, 1995). Tooth size furnishes human biologists with an insight into the genetic relation between populations and environmental adaptation (Margetts and Brown, 1978; Kieser, 1990). Of clinical interest is the interrelation between tooth size and arch align- ment in which large teeth are associated with dental crowding (Lundstrom, 1969; Doris et al., 1981; Radnzic, 1988). Moreover, a relation has been noted between tooth size and third molar eruption and impaction (Forsberg, 1988). Tooth size exhibits a continuous range of vari- ation among individuals and between populations. Accumulated evidence indicates that tooth size reflects a complex interaction between a variety of genetic and environmental factors (Townsend and Brown, 1978; Garn et al., 1979; Alvesalo et al., 1991). Sexual dimorphism in the extent and pattern of tooth-size variation characterizes modern *To whom all correspondence should be addressed. humans. Several studies have demonstrated that mesiodistal crown diameters of males are consider- ably larger than those of females, the largest differ- ences being found in the canines (Seipel, 1946; Moorees et al., 1957; Barrett et al., 1963). Sexual dimorphism in tooth size is more pronounced in the permanent than in the deciduous dentition (Garnet al., 1967; Black, 1978). The explanations proposed for tooth-size dimorphism between males and females include: sex variation in odontogenic timing and enamel thickness; males having larger bodies than females; effects of sex chromosomes in promot- ing tooth growth; and other hormonal influences (reviewed by Kieser, 1990). Because odontometric data on the Jordanian population are not available and there is a paucity of such data on Arabs in gen- eral, we have now sought to determine the mesiodis- tal crown diameters of the permanent teeth in Jordanians and to compare our findings with those for similar and different ethnic groups. The sample comprised 198 individuals (86 males and 112 females) who were born of Jordanian parents and grew up in Jordan. All were apparently healthy and presented to the dental clinic at Jordan University of Science and Technology for orthodon- tic and other treatment needs. The mean age (+SD) of the males was 15.7 (+2.6) years and females 15.1 (+__2.2) years. Teeth were selected for measurement only if they were morphologically normal, not 641