Correspondence between enamel hypoplasia and odontometric bilateral asymmetry in Australian twins

Abstract

Four aspects of enamel hypoplasia of the maxillary central incisor and mandibular canine (hypoplasia presence, width, cumulative width, and crown position) were correlated with directional and fluctuating measures of bilateral odontometric asymmetry in a large panel (n = 950) of South Australian twins. Hypoplasia and asymmetry are thought to reflect general developmental disruption, but they show few correlations beyond the expected statistical type I error. This may relate to differences in their specific etiology, the composite nature of overall crown dimensions, a general lack of stress, and the extended period of formation of dental crowns. In contrast, asymmetry is marginally more detectable in a subsample separated according to hypoplastic teeth, suggesting that correspondence may be clearer in comparisons at the population rather than individual level. The most notable difference is the greater variability of asymmetry measures in hypoplastic individuals.

Exploring the relationship between hypoplasia and odontometric asymmetry in Isola Sacra, an imperial roman necropolis

“…A second issue extending from the results of this study was that PS data did not return more or stronger positive significant results than P/A data. As discussed above, no study has yet (Blakey, 1981;Clarke, 1978;Hillson, 1996) correlated larger or deeper enamel hypoplasias to stronger, prolonged stresses and, as such, perhaps appearance is not indicative of severity (Corruccini et al, 2005). Before concluding that appearance is not indicative of severity, however, using P/A and PS data for correlations with a larger sample from a population known to have a heavy stress load would be prudent.…”

“…First, different timing and growth sequences for the deposition of enamel in the tooth classes may have been a factor (Goodman and Armelagos, 1985;Guatelli-Steinberg and Lukacs, 1999;Hillier and Craig, 1992). Perhaps teeth with larger enamel surfaces and complex structures taking longer to complete developmentally do not record asymmetry to the same degree as hypoplasia (Corruccini et al, 2005). The complexity and surface area of molars thus may require protracted periods of stress before the asymmetry of molars correlate to presence or degree of hypoplasia.…”

“…Between groups variance using hypoplasia present as a predictor variable integrates the two datasets given that FA may be an expression of a genetic trait as acted on by the environment. Additionally, as asymmetry is a measure of variance about the mean, population level comparisons may reveal more significant findings, especially when comparing samples that have extreme variation in environmental stress exposure and/or skeletal and dental evidence of prolonged or acute stressors (Corruccini et al, 2005).…”

“…In brief, hypoplasias in mesial teeth reflect stress occurring in shorter developmental periods (Goodman and Armelagos, 1985), while the asymmetry of distal teeth reflects stresses occurring over longer developmental periods (Corruccini et al, 2005;Naugler and Ludman, 1996;Perzigian, 1977;Sofaer, 1979). As such, enamel hypoplasia and odontometric asymmetry are under similar developmental influences etiologically and may have similar thresholds of susceptibility that differ in degree but not kind.…”

Genetic and Environmental Influences on Dentofacial Structures and Oral Health: Studies of Australian Twins and Their Families

“…development: at the stage when all primary teeth were present (around 3-5 years), when children had mixed dentitions (around 8-10 years), and when all the permanent teeth were present except third molars (around 12-14 years). Collection of records is now almost complete and several analyses have been completed or are underway, including some with collaborators from Japan and the United States (Corruccini et al, 2005;Richards et al, 1997).…”