Developmental communalities in tooth emergence timing.

Intercorrelations and communalities are now well known for tooth formation (Garn et al., J Dent Res 39:1049, 1960), crown size of the permanent teeth (Moorees and Reed, Arch Oral Biol 9:685, 1964; Garn et al., J Dent Res 44:350, 1965), the deciduous teeth (Garn et al., JDentRes 56:1214, 1977), and crown size of deciduous teeth during odontogenesis (Garn et al., J Dent Res 58:554, 1979). However, comparable analytic information has not been presented for postnatal tooth emergence timing of 11 through M2. To explore these emergence relationships and their relative magnitudes, tooth emergence (timing) correlations were calculated using coded emergence data derived from serial casts of 204 participants in the Longitudinal Study of the University of Michigan (Moyers et aL, Standards of Human Occlusal Development, Ann Arbor: The Center for Human Growth and Development, 1976). Individual ages of tooth emergence were Z-scored for males and females separately for each of 28 permanent teeth, and the entire matrix of 121 pooled-sex tooth-pair intercorrelations was then computer correlated. Correlation coefficients for intra-quadrant pairs, antimeres, isomeres, and teeth separated by numbers of intervening teeth were separately averaged using the z transform of r As snown in the Table, where correlations are