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Contributions of genetics and of the environment to variation in human tooth size are discussed. A significant effect of the environment shared by twins, uterine or early in life, was found for mesiodistal (MD) and buccolingual (BL) diameters of maxillary first molars. Significant non-additive genetic variation was seen in MD diameters of canines and first premolars. That would be consistent with selective pressures at some stage in human evolution.

Symmetry is a major correlate of physical attractiveness across species, including humans. Investigating the nature of this relationship has been difficult, however, for several reasons, including the facts that variance in symmetry is attributable to more than one source and is often correlated with other variables related to attractiveness. This study assessed the role of facial symmetry in relation to perceptions of facial attractiveness. Some of the natural covariates of symmetry were controlled for by comparing the symmetry and attractiveness differentials between monozygotic co-twins, who are genetically, but not developmentally, identical. The more symmetric twin of a pair was consistently rated as more attractive, and the magnitude of the difference between twins in perceived attractiveness was directly related to the magnitude of the difference in symmetry.

Longitudinal studies of aboriginal children over a 20-year period have drawn attention to the wide variation in morphological features of the dentition and the way in which occlusal relationships develop. This paper summarizes some important determinants of optimal occlusal development, namely, tooth size relationships within and between dentitions, the patterns of alveolar growth, and tooth migrations during the transition from primary to permanent teeth and the nature of growth changes in the dental arches. Dental occlusion constantly changes throughout life in response to changing functional requirements. Observations limited to cross-sectional material provide an incomplete, and sometimes misleading, concept of dental occlusion and masticatory function.

The major current overviews establish that generalized development stress between ages 0-5 underlines most permanent tooth hypoplasias. Fluoridation of metropolitan water has emerged as the statistically strongest hypoplasia-preventing factor.