Decline in enamel hypoplasia in relation to fluoridation in Australians.

Enamel hypoplasias are thought to represent calcification disruption indicative of metabolic stress during development. Hypoplasias of permanent maxillary central incisors and mandibular canines have undergone a notable reduction in frequency between Euro-Australian twins born around 1965 and those born ca. 1990. Even when scored very liberally these linear defects are 3.1-4.6 times as prevalent in the earlier Australians, and the discrepancy is proportionately greater among strictly scored defects. Likely correlates of this secular trend logically include reduced childhood fevers and clinical intervention to reduce circum-natal stresses acting on cotwins. However, fluoridation of metropolitan water has emerged as the statistically strongest hypoplasia-preventing factor.

Dietary consistency and craniofacial development related to masticatory function in minipigs.

Since the 1890s oral biological researchers have been interested in the idea that strenuous mastication of unprocessed food will stimulate proper oral-facial growth and occlusal relationships. Conversely, lack of such function due to consumption of refined food is one hypothesis among many for the etiology of malocclusion in industrialized humans. Adequately controlled experimental testing of the idea has been limited to rats. To investigate the "disuse" theory in a larger-bodied and more occlusally relevant animal model, we raised four Yucatan minipigs from weaning on hard diet (HD) and another four on softened but equivalent diet (SD). The animals were monitored for eight months, sacrificed, and then occlusal and osteometric data collected. Variations due to dietary regime are pervasive and not due to caries, periodontitis, or attrition differences. Whereas HD body weight is 10% greater than SD, the deep masseter is 25% greater, with similar disproportion in superficial masseter and temporalis weight. Facial prognathism, arch narrowness, tooth crowding/maleruption and posterior cranial tapering are markedly different in the two groups. A curious posterior torsional difference in the mandibular rami, as well as broadness and flatness of the mandibular symphysis, also occur in SD. We performed a Q-mode principal coordinates analysis of the 19 logged variables for the specimens, bootstrapping the variable list, to demonstrate a statistically significant (P < .01) overall pattern of dramatic differences. Having controlled other celebrated orthodontic etiologies (genetic background, respiratory mode, infectious degeneration and interproximal attrition), these results support the proposition that dietary consistency relates directly to human craniofacial growth.

Congenital syphilis in the past: slaves at Newton Plantation, Barbados, West Indies.

Hutchinson's incisors and Moon's molars are specific lesions of congenital syphilis. The extensive but fragmentary clinical literature on these conditions describes reduced dimensions and thin enamel in the permanent incisors and first molars, crowding and infolding of the first molar cusps, notching of the upper incisors, and apical hypoplasias of the permanent canines. A Barbados slave cemetery (ca. 1660-1820 AD) includes three individuals with these features, suggesting a frequency at birth of congenital syphilis in the population approaching 10%. These three cases show triple the frequency of all hypoplasias and more than seven times the frequency of pitting hypoplasia present in the remainder of the series. The recognizable congenital syphilis cases account for much of the remarkably high frequency of hypoplasias in the series as a whole. We infer that syphilis contributed substantially to morbidity, infant mortality, and infertility in this population. Presence or absence of congenital syphilis may account for much of the variability in health and mortality seen among nineteenth century African-American populations.

PIP: 2 anthropologists examined the teeth of 104 slaves buried between 1660 and 1820 who had worked on Newton Plantation in Barbados, West Indies, and were excavated between 1971 and 1973 to look for obvious evidence of congenital syphilis. 84 bodies still possessed either incisors or first molars in good enough shape for the anthropologists to examine. 3 young adult or adolescent slaves had dental lesions indicating congenital syphilis (Hutchinson's incisors and/or Moon's molars). These 3 cases had a frequency of all hypoplasias 3 times that of the remaining slaves and a frequency of 7.5 times of pitting hypoplasia. The frequency of congenital syphilis was at least 3%. Literature data indicate that congenital syphilis features are evident in 33% of cases; therefore, the frequency of congenital syphilis at birth was likely to be around 10%. None of the cases were less than 5 years old. Further, wear and cavity-related tooth loss eliminated evidence of congenital syphilis in people at least 30 years old. The anthropologists gathered that syphilis was responsible for sizeable illness, infant deaths, and infertility among these slaves. They also reviewed 3 dental studies of 3 US African American cemeteries. The individuals in 2 cemeteries had no evidence of congenital syphilis and were in relatively good health, while individuals from the postslavery period had evidence of congenital syphilis (5%). The researchers suggested that presence of absence of congenital syphilis may explain much of the variance in mortality and health noted among 19th century African American populations.

Metrical reconsideration of the Skhul IV and IX and Border Cave 1 crania in the context of modern human origins.

The "out-of-Africa" models for origins of modern Homo sapiens incorporate Skhul as one site documenting that early origination. However, only Skhul V is usually considered in the comparative craniology of the question, neglecting the other substantial crania, Skhul IV and IX. Craniometric comparison demonstrates that IV and IX amplify the picture of continuous gradations of Neandertal-to-modern variations throughout the Levant; much variation is thus represented within this one site, raising serious questions about Neandertals and moderns being discrete and long-separated species. Qafzeh 6 too is craniophenetically closer to Neandertals than to the true anatomically modern people of the European Upper Paleolithic. Proper distance analysis of Border Cave 1 cranium shows it is actually far removed from modern African populations. References to Qafzeh, Skhul, and Border Cave as "fully anatomically modern" require reconsideration.

Genetic epidemiology of non-insulin-dependent diabetes mellitus in north India: preliminary analyses of some genetic markers in Punjabis.

Studies on monozygotic (MZ) twins and admixed populations show that the predisposition to non-insulin-dependent diabetes mellitus has a large genetic component. We have examined the distribution of some genetic polymorphisms (ABO, GLO, ESD, AK, ACPA, and GPI) in control and diabetic Punjabis from north India. The distribution of various genetic markers indicate that the differences between the control and diabetic samples are statistically not significant. Moreover, a contingency chi-square analysis over all loci suggests nonsignificant genetic differentiation (p = 0.50) between the Punjabi samples.

Occlusal variation in Australian aboriginals.

Variation of dental occlusion around established norms has frequently been related to industrialized or modernized life habits. This tendency has been tested among samples (n = 48) of older (originally nomadic) and younger (settled and rationed) Australian Aboriginals. Although significant differences are found in incisor relation traits, tooth malalignment, and relative arch breadth, these are slight compared to some other studies of peoples undergoing one-generation dietary westernization. Reasons for this might relate to concomitantly subtle differences in diet or masticatory habits, genetic buffering, attrition gradient, tooth size, biased sampling according to tooth retention, or fluoride in water supplies.

Genetic and environmental determinants of dental occlusal variation in twins of different nationalities.

We have compared 10 occlusal traits in 358 monozygous and dizygous twin pairs in 4 different samples and estimated genetic variances for these features. Variable and frequently nonsignificant genetic variance was noted across samples for incisal overbite and overjet, sagittal molar relationship, posterior crossbite, and rotations and displacements of anterior teeth. Heritability estimates (when appropriately calculated) were low in magnitude (0-40%) and erratic, emphasizing the importance of environmental influences on occlusal variation and the variability of apparent genetic determinants with respect to the environment or population in which they are measured.

Australian aboriginal tooth succession, interproximal attrition, and Begg's theory.

In 1954, P.R. Begg analyzed interproximal attrition as a prehistorically universal mechanism to reduce tooth size. With modern processed diets and the virtual disappearance of constant interproximal attrition, Begg asserted, teeth remain too large for the arches and become crowded. Later investigators have questioned Begg's estimate of attritional tooth-size reduction, as well as aspects of his theory relating the succession sequence of permanent teeth to different malocclusions. The present paper examines the theory using longitudinal casts and records of modern Australian aborigines who are among the first generation lacking notable interproximal attrition thanks to a "modernized" diet. Deciduous and permanent tooth size, arch size, and occlusal relational variables were analyzed with respect to the expected occlusal outcomes in the absence of attritional tooth reduction. Permanent incisor overjet correlated with crowding status, as predicted by Begg. On the other hand, longer teeth did not relate to crowding in general nor to crowding in relevant local areas or during developmental stages. Unfavorable leeway space did not relate clearly to crowding or other malocclusions. Lowered correlations among structures and narrowness of the maxilla related more significantly to malocclusion. These results are in keeping with recent thinking that small jaws rather than large teeth underlie tooth/arch discrepancy.

Genetic epidemiology of non-insulin-dependent diabetes mellitus (NIDDM) in north India: distribution of Gm and Km allotypes in 'Punjabis'.

Non-insulin dependent diabetes mellitus (NIDDM) is becoming endemic to modernizing and urbanizing populations all over the globe. The data on Gm and Km allotypes in the 'Punjabis' (n = 165) from north India show an interesting association with NIDDM. Differences between diabetic and control samples for the Km allele frequency distribution approach significance (p = 0.0897). The observed phenotypic diversity in the Gm system in diabetics indicates genetic heterogeneity in the disease group. A significant decrease (or absence) of phenotype Gm1,3,17; ;5,21 (p = 0.0119), and presence of phenotype Gm1,2,3,17; ;5,21 (p = 0.0158) in diabetics may constitute a risk factor for this disorder in 'Punjabis'.

"Orthodontistry" and dental occlusion in Etruscans.

Specimens dating back to the VIII Century B.C. indicate Etruscans may have been the first people to employ orthodontic bands to improve tooth alignment. A survey of dental occlusion in Etruscan cranial remains, however, shows very good typical occlusion and almost no crowding. Thus, these people do not represent the earliest development of epidemiologically high prevalence of malocclusion, a feature instead reserved for the later industrial world.

Odontometric asymmetry in Punjabi twins with special reference to methods for detecting spurious genetic variance.

Bilateral human odontometric asymmetry generally shows very little genetic variance. In Indian twins, using the simplest methods, unusual levels of disproportionate monozygous similarity and/or dizygous dissimilarity for asymmetry, giving the appearance of significant genetic determinance, were found. Thus this dental asymmetry constituted an interesting test case for the application of more exact methods for the detection of zygosity bias; these invalidated the spuriously significant genetic variance ratios. Therefore the predominantly environmental influences on bilateral dental asymmetry are confirmed.

Implications of tooth root hypercementosis in a Barbados slave skeletal collection.

A 17th- to 19th-century cemetery sample of 104 slaves from Newton Plantation (Barbados) shows uniquely high hypercementosis prevalence, as well as unexpectedly high and variable skeletal lead content. A variety of biological and archeological factors indicates that individuals with lower amounts of these anomalies (relative to age at death) were probably African-born, first-generation slaves. The hypercementosis is related to the progression of periodontal disease as assessed from alveolar bone. Although the hypercementosis is endemic in the Caribbean black population, it does not as yet have a clear explanation. We suggest the etiology might relate to chronic malnutrition involving periodic, seasonal rehabilitation.

Familial segregation in the iron age community of Alfedena, Abruzzo, Italy, based on osteodental trait analysis.

Numerous authors have studied human cemetery remains with an eye toward identifying different socially stratified ethnic or kinship groups within the same population. The interments of the protohistoric graveyard of Alfedena, Abruzzo, Italy, show recurrent organization in separate structures, suggesting to several involved archaeologists that these structures express family groups and/or differences in social function of the occupants. This has induced us to analyze the possible biological implications of specific models for kinship groups, lineages, or mating forms in graveyards. One hundred ninety-six metric and nonmetric skeletal and dental variables were collected. The analysis of metric features was performed by analysis of variance and by calculating divergences between each pair of individuals. The position parameters of the inter-and intragroup distance distributions were then compared by means of nonparametric tests. The nonmetric features were analyzed by contingency tables. The partition of intercircle variance is twice as frequently significant for males (20 variables) as for females (10). For metric variables in males, 20.9% displayed a probability level less than 5% for the null hypothesis of random distribution of individuals in the circles. Fewer (10.3%, but still more than expected at random) reached this level of significance for the females. In the male groups, 19% of nonmetric features showed significant frequency differences, but this was true in only 4.3% of the females.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative genetic variance and heritability of dental occlusal variables in U.S. and Northwest Indian twins.

Genetic variance analysis of 15 dental occlusal and arch variables is based on cross-cultural comparison of twin variances (U.S. Whites and Northwest Indian Punjabis). Both samples exhibit high genetic versus environmental partition of variance. However, monozygotes and dizygotes have unequal variance, which invalidates conventional genetic variance ratios. The pattern of environmental biases on the zygosities is quite different in the two groups. Revised estimates that acknowledge zygosity heterogeneity (hence unequal environmental influences) are generally much lower for occlusal traits, whereas arch size measurements are unaffected.

Odontometric variations of permanent crown in Punjabi and U.S. twins.

The study reports odontometric variations within and between Punjabi and U.S. twins. The data are based on 23 MZ and 35 DZ Punjabi twin pairs and 32 MZ and 43 DZ U.S. pairs. None of the t' tests indicates differences between MZ and DZ mean dental dimensions in either sample. Mean tooth dimensions of Punjabi twins are in general greater than those of U.S. twins with significant differences for about 25% of the traits. Coefficient of variation is highest in lateral incisors and canines and lowest in first molars in both samples. The two samples differ more in their variances than in their means. The results indicate that buccolingual dimensions of mandibular traits are under relatively greater selection pressure.