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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.

Objective: To investigate facial asymmetry associated with both deformational and synostotic plagiocephaly and to identify variables based on skeletal landmarks that distinguish the conditions and quantify severity. Design: Retrospective, cross sectional. Setting: Australian Craniofacial Unit, Adelaide. Main Outcome Measures: Proportional differences between bilateral distances and principal component (PC) analysis of the skeletal landmarks. Patients: The three-dimensional positions of 78 osseous landmarks were determined from computed tomography (CT) scans of 21 patients with deformational plagiocephaly (DP), 20 patients with unilateral coronal synostosis (UCS), and 2 patients with unilateral lambdoid synostosis (ULS). Results: For both DP and UCS, significant asymmetry was found for the orbital depths, mandibular lengths, maxillary depths, zygomatic arch lengths, lateral base of the parietal bone, and the angle between the anterior and the posterior cranial base projected onto the axial plane. The small sample size for ULS precluded definitive statistical statements but allowed some useful comparisons with the other conditions. The first three PC scores were able to distinguish among the three conditions and which side was affected. Conclusions: The asymmetry of the cranial base and facial structures, arising from localized abnormality or deformational forces in either the frontal or the occipital regions, can be quantified by a plethora of bilateral features or summarized by PC analysis. [ABSTRACT FROM AUTHOR]

Background: Easily applied, age-specific standards are useful in assisting clinicians to decide whether the extent of tooth wear observed in a given patient at a specific age is acceptable or whether intervention is indicated. Method: A simple method of scoring tooth wear and previously established mathematical relationships between tooth wear scores and age, provide the basis of a method for predicting tooth wear scores. In its most specific form, the method can be used to predict tooth wear scores for individual patients at subsequent ages. Alternatively, tables or graphs can be consulted to provide a less precise prediction of tooth wear that can assist clinicians to decide whether the amount of wear reflects high, moderate or low rates of wear at the specified age. Conclusion: In cases where there is no reason to believe that aetiological factors have changed significantly over time, data obtained from the methods described can assist clinicians to plan appropriate management for patients presenting with unacceptable levels of tooth wear. Key words: Tooth wear; attrition; erosion; abrasion; scoring. [ABSTRACT FROM AUTHOR]