Dimensional Communalities of the Deciduous Teeth

Abstract

Although there have been numerous studies of the extent to which the crown dimensions of the permanent teeth are correlated (MOORREES and REED, Arch Oral Biol 9:685, 1964; GARN, LEWIS and KEREWSKY, J Dent Res 44:350, 1965) comparable information on deciduous tooth dimensional communalities is meagre. Moreover, it is not known whether the crown dimensions of the deciduous teeth show different patterns of correspondence from those exhibited by the permanent teeth of the same individuals. Turning, then, to optical-scanner (OPTOCOM) mesiodistal crown measurements of 204 boys and girls from Southeastern Michigan (VAN DER LINDEN et al, J Dent Res 51: 1100, 1972; GARN et al, J Dent Res 56:697, 1977) complete intercorrelation matrices were calculated for 20 deciduous teeth, for boys and girls respectively, and compared with correlations for 20 successional (permanent) teeth from the same individuals. Since correlations involving the right and left sides were not systematically different, the sides were pooled to simplify the presentation. However, crown-size correlations for boys and girls were analyzed separately, since a systematic sex difference emerged. Moreover, attention was given to individual teeth, to morphological classes, and to between teeth within each arch, in order to test for a distance effect. As shown in the table, deciduous tooth intercorrelations are slightly higher for boys in the sample (R = 0.54) than for girls (R = 0.45), a trend significant by sign test for 20 paired correlations (X2 = 7.2). Within the arches, the highest correlations are for teeth of the same morphological class (r = 0.64), then those for adjacent teeth (r = 0.56) and then for teeth more widely separated. Mean values for r are 0.43, 0.45 and 0.46 for 1, 2 and 3 intervening teeth, respectively. Finally, the mean value of r for 20 deciduous teeth is slightly higher than the mean mesiodistal crown-