The chronological distribution of enamel hypoplasias from prehistoric Dickson Mounds populations

The chronological distributions of enamel hypoplasias (indicators of nonspecific stress) are assessed for 111 individuals from two prehistoric populations from Dickson Mounds, Lewiston, Illinois. The earlier population (circa A.D. 950-1150) involves a transition from an indigenous gathering-hunting tradition to increasing adoption of Mississippian lifeways. The later population (circa A.D. 1150-1300) is fully Mississippian (MM). Based on the occurrence of hypoplasias on all permanent teeth except third molars, 14 half-year periods from birth to 7.0 years are graded for evidence of hypoplasia-stress. Both populations have a low frequency of hypoplasia which occur before 2 years of age and after 4 years of age. A common peak frequency of hypoplasias between 2.0 and 4.0 years is suggestive of an elevated degree of stress at weaning. The peak frequency of hypoplasias is earlier in the MM (2.5-3.0 years versus 3.0-3.5 years in the pre-Mississippian population). In addition, the rise to and decline from peak frequency occurs approximately 0.5 years earlier in the MM. The earlier and sharper rise to peak frequency suggests earlier and more severe weanling-related stress. Hypoplasias chronologies are undoubtedly influenced by age-related host resistance factors (Sarnat and Schour, 1941). Nevertheless, these data demonstrate that populations may vary in their chronological distribution of hypoplasias and that these variations may provide useful information on age-related patterns of exposure to environmental stressors.     

Frequency and distribution of enamel hypoplasias in a historic skeletal sample

A skeletal sample of 296 individuals from a 19th century American poorhouse cemetery is examined for the frequency and chronological distribution of linear enamel hypoplasias on the mandibular canines and maxillary central incisors. Dental enamel hypoplasias may be considered to be indicators of increased exposure to health risk at the time of weaning. The purpose of this study is to examine childhood stress and provide a relative measure of that stress, as evidenced by hypoplasias, in a historic sample that represents an industrializing population. The frequency of enamel hypoplasias per individual by tooth ranged from 70 to 73%, with a peak age at stress of 2.5 to 3 years for the maxillary central incisor and 3.5 to 4 years for the mandibular canine. There were no significant differences in the presence of hypoplasias between males and females. The peak age at stress between 2.5 and 4 years in this 19th century sample transects the ranges reported for prehistoric populations (2-6 years) and for modern groups (0-3 years). These results indicate that the stress associated with weaning probably occurred earlier in incipient industrial societies than in prehistoric hunter/gatherers and agriculturalists, yet not as early as in modern industrial groups. The high level of childhood stress in this skeletal sample compared with that of other samples may indicate a change in health, at least among the lowest class, associated with the cultural transition from an agricultural to an industrial society.     

Frequency and chronological distribution of dental enamel hypoplasia in enslaved African Americans: A test of the weaning hypothesis

The dentition of 27 enslaved African Americans from archaeological sites in Maryland and Virginia were examined. All 17 males and 7 of the 10 females in this study exhibited enamel hypoplastic defects indicative of systemic nutritional and disease stresses interfering with amelogenesis. Estimates of the ages of occurrence of these defects show that most occur between 1.5 and 4.5 years of age, 0.5–3.75 years later than historically documented weaning age (9–12 months of age) in similar plantation populations. Comparisons are made with studies of dental enamel hypoplasia in contemporaneous enslaved and free African American populations, including our data on 75 individuals from the First African Baptist Church cemetery in Philadelphia. These populations were highly stressed. While there appears to be a modest effect of early weaning stress, no direct relationship of peak frequencies to weaning age can be shown. These data raise questions about the attribution of peak hypoplasia frequencies to age at weaning or “post-weaning” stresses in previous paleopathological studies. High hypoplasia frequencies during the middle years of enamel development are more likely the result of a combination of 1) multiple environmental stresses, 2) differences in hypoplastic susceptibility in enamel, and 3) random factors. © 1994 Wiley-Liss, Inc.     

Prevalence and etiology of linear enamel hypoplasia in monkeys and apes from Asia and Africa

Ninety-seven specimens of sympatric monkeys and apes from East Malaysia and 115 monkeys and apes from West Africa are examined in order to evaluate the magnitude and nature of the great ape-monkey linear enamel hypoplasia (LEH) 'dichotomy'. This study demonstrates that great apes from both regions have a higher incidence of LEH and repetitive LEH than do gibbons and monkeys. However, the authors find that the dichotomy is not as clear-cut as previous research suggests, since some monkey samples exhibit high LEH frequencies. The authors evaluate the potential influence of great ape-monkey differences in crown height on this dichotomy. They show that canine crown height variation is weakly associated with LEH variation. Differences between monkeys and great apes in their crown formation spans and in their experience of environmental stress may be more likely causes of the dichotomy.     

Prevalence and the duration of linear enamel hypoplasia: a comparative study of Neandertals and Inuit foragers

As a dental indicator of generalized physiological stress, enamel hypoplasia has been the subject of several Neandertal studies. While previous studies generally have found high frequencies of enamel hypoplasia in Neandertals, the significance of this finding varies with frequencies of enamel hypoplasia in comparative samples. The present investigation was undertaken to ascertain if the enamel hypoplasia evidence in Neandertals suggests a high level of physiological stress relative to a modern human foraging group, represented here by an archaeological sample of Inuit from Point Hope, Alaska. Unlike previous studies, this study focused specifically on linear enamel hypoplasia (LEH), emphasizing systemic over localized causes of this defect by considering LEH to be present in an individual only if LEH defects occur on two anterior teeth with overlapping crown formation periods. Moreover, this study is the first to evaluate the average growth disruption duration represented by these defects in Neandertals and a comparative foraging group. In the prevalence analysis, 7/18 Neandertal individuals (from Krapina and southern France) and 21/56 Neandertal anterior teeth were affected by LEH, or 38.9% and 37.5% respectively. These values do not differ significantly from those of the Inuit sample in which 8/21, or 38.1% of individuals, and 32/111, or 28.8% of anterior teeth were affected. For the growth disruption duration analysis, 22 defects representing separate episodes of growth disruption in Neandertals were compared with 22 defects in the Inuit group using three indicators of duration: the number of perikymata (growth increments) in the occlusal walls of LEH defects, the total number of perikymata within them, and defect width. Only one indicator, the total number of perikymata within defects, differed significantly between the Inuit and Neandertal groups (an average of 13.4 vs. 7.3 perikymata), suggesting that if there is any difference between them, the Inuit defects may actually represent longer growth disruptions than the Neandertal defects. Thus, while stress indicators other than linear enamel hypoplasia may eventually show that Neandertal populations were more stressed than those of modern foragers, the evidence from linear enamel hypoplasia does not lend support to this idea.     

Finite element analysis of stress distribution in intact and porcelain veneer restored teeth

The aim of this study was to investigate the stress distribution generated in a veneer restoration of an upper central incisor compared to intact teeth using the finite element analysis after applying a lingual buccal loading at the incisal edge. Methods: Two models were developed: one model contained enamel, dentine, cementum, periodontal ligament, cortical and trabecullar bones, and the other model was a veneer restoration; both models were developed using MSC/Nastran software (MacNeal-Schwendler Corporation, Los Angeles, CA, USA) as the pre- and post-processor. A 10-N load was applied at the incisal edge from the lingual to the buccal side to simulate oral conditions in this area (protrusion). Results: Von Mises stresses were then analysed for three different regions: A-B (enamel elements under the veneer or second enamel layer), A′-B′ (buccal enamel and/or veneer element layer) and C-D (lingual enamel elements layer). A higher stress mode was observed for both models at the lingual cervical region. Conclusions: The presence of a veneer restoration on the incisors is a good alternative to mimic the behaviour of enamel under protrusion loading conditions. The use of veneers to replace enamel during rehabilitations is recommended.     

Basics in paleodemography: a comparison of age indicators applied to the early medieval skeletal sample of Lauchheim

Recent advances in the methods of skeletal age estimation have rekindled interest in their applicability to paleodemography. The current study contributes to the discussion by applying several long established as well as recently developed or refined aging methods to a subsample of 121 adult skeletons from the early medieval cemetery of Lauchheim. The skeletal remains were analyzed by 13 independent observers using a variety of aging techniques (complex method and other multimethod approaches, Transition Analysis, cranial suture closure, auricular surface method, osteon density method, tooth root translucency measurement, and tooth cementum annulation counting). The age ranges and mean age estimations were compared and results indicate that all methods showed smaller age ranges for the younger individuals, but broader age ranges for the older age groups.     

Quantitative trait locus effects and environmental interaction in a sample of North American barley germ plasm

Quantitative trait locus (QTL) and QTL x environment (E) interaction effects for agronomic and malting quality traits were measured using a 123-point linkage map and multi-environment phenotype data from an F₁-derived doubled haploid population of barley (Hordeum vulgare). The QTL × E interactions were due to differences in magnitude of QTL effects. Highly significant QTL effects were found for all traits at multiple sites in the genome. Yield QTL peaks and support intervals often coincided with plant height and lodging QTL peaks and support intervals. QTL were detected in the vicinity of a previously mapped Mendelian maturity locus and known function probes for- and-amylase genes. The average map density (9.6 cM) should be adequate for molecular marker-assisted selection, particularly since there were few cases of alternative favorable alleles for different traits mapping to the same or adjacent intervals.Oreg Agric Exp Stn J No. 10150     

Exploration of sample size and diatom-based indicator performance in three North American phosphorus training sets

Three large training sets were investigated to determine optimal sample sizes for diatom-based inference models. The sample sets represented (1) assemblages from Great Lakes coastlines, (2) phytoplankton from the pelagic Great Lakes and (3) surface sediment assemblages from Minnesota lakes. Diatom-based weighted average models to infer nutrient concentrations were developed for each training set. Training set sample sizes ranging from 10 to the maximum number of samples were created through random sample selection, and performance of each model was evaluated. For each model iteration, diatom-inferred (DI) nutrient data were related to stressor data (e.g., adjacent agricultural or urban development) to characterize the ability of each model to track human activities. The relationships between model performance parameters (DI-stressor correlations and model r ², error and bias) and sample size were used to determine the minimum sample size needed to optimize models for each region. Depending on the training set, at least 40–70 samples were needed to capture the variation in diatom assemblages and environmental conditions to such a degree that non-analog situations should be rare and so should provide an unambiguous result if the model was applied to any sample assemblage from the region. It is recommended that one exercises caution when dealing with smaller training sets unless there is certainty that the selected samples reflect the regional variability in diatom assemblages and environmental conditions.     

Experiences and perceptions of oral health and oral health care among a sample of older New Zealanders

doi: 10.1111/j.1741‐2358.2010.00402.x Experiences and perceptions of oral health and oral health care among a sample of older New Zealanders Background: Most research on older people’s oral health has been quantitative. A need for more in‐depth understanding of the oral health of that age group has pointed to a need for more qualitative investigations. Objective: To explore experiences and perceptions of oral health and oral health care among an ethnically‐mixed sample of older New Zealanders. Methods: In‐depth interviews were conducted with 24 older people in two communities in New Zealand’s South Island. Thematic analysis of transcribed data was undertaken. Results: Three main themes that emerged were: (1) the processes of negotiating a tension between cost and convenience of access; (2) the experiential constraining of oral health maintenance; and (3) trusting in dental professionals. These serve to organise processes such as normalising, justifying and social comparisons that create an equilibrium or tolerance and acceptance of what might otherwise be considered to be relatively poor oral health. Conclusions: We identified a number of shared experiences which affect older people’s ability to maintain their oral health in the face of material and social barriers to oral health care. Because expectations were generally lower, there was greater concordance between experience and expectation, and people tended to be fairly satisfied with their oral health and the care they had received.     

Isolation‐driven divergence: speciation in a widespread North American songbird (Aves: Certhiidae)

Lineage, or true ‘species’, trees may differ from gene trees because of stochastic processes in molecular evolution leading to gene‐tree heterogeneity. Problems with inferring species trees because of excessive incomplete lineage sorting may be exacerbated in lineages with rapid diversification or recent divergences necessitating the use of multiple loci and individuals. Many recent multilocus studies that investigate divergence times identify lineage splitting to be more recent than single‐locus studies, forcing the revision of biogeographic scenarios driving divergence. Here, we use 21 nuclear loci from regional populations to re‐evaluate hypotheses identified in an mtDNA phylogeographic study of the Brown Creeper (Certhia americana), as well as identify processes driving divergence. Nuclear phylogeographic analyses identified hierarchical genetic structure, supporting a basal split at approximately 32°N latitude, splitting northern and southern populations, with mixed patterns of genealogical concordance and discordance between data sets within the major lineages. Coalescent‐based analyses identify isolation, with little to no gene flow, as the primary driver of divergence between lineages. Recent isolation appears to have caused genetic bottlenecks in populations in the Sierra Madre Oriental and coastal mountain ranges of California, which may be targets for conservation concerns.     

Three-dimensional numerical simulation of stress induced by different lengths of osseointegrated implants in the anterior maxilla

Lower survival rates were observed for the implant placed in the anterior maxilla. The purpose of this study was to investigate the influence of different implant lengths on the stress distribution around osseointegrated implants under a static loading condition in the anterior maxilla using a three-dimensional finite element analysis. The diameter of 4.0 mm external type implants of different lengths (8.5 mm, 10.0 mm, 11.5 mm, 13.0 mm, 15.0 mm) was used in this study. The anterior maxilla was assumed to be D3 bone quality. All the material was assumed to be homogenous, isotropic and linearly elastic. The implant–bone interface was constructed using a rigid element for simulating the osseointegrated condition. Then, 176 N of static force was applied on the middle of the palatoincisal line angle of the abutment at a 120°angle to the long axis of abutment. The von Mises stress value was measured with an interval of 0.25 mm along the bone–implant interface. Incremental increase in implant length causes a gradual reduction of maximum and average von Mises stress at the labial portion within the implant. In the bone, higher stress was concentrated within cortical bone area and more distributed at the labial cortex, while cancellous bone showed relatively low stress concentration and even distribution. An increase in implant length reduced stress gradients at the cortical peri-implant region. Implant length affects the mechanisms of load transmission to the osseointegrated implant. On the basis of this study the biomechanical stress-based performance of implants placed in the anterior maxilla improves when using longer implants.     

Logging and Edaphic Factors in the Invasion of an Asian Woody Vine in a Mesic North American Forest

Factors contributing to an invasion of the Asian woody vine Celastrus orbiculatus in a mesic forested Massachusetts (USA) sanctuary were investigated. Planting germinated C. orbiculatus seeds in the field revealed that, although they tolerate a wide range of conditions, seedlings grow largest in moist circumneutral soil under high irradiance. A study of naturally occurring vines in a logged forest suggested that C. orbiculatus invaded two years after harvest, and invasion may have been triggered by logging disturbance. Vine stems were more abundant on former logging roads than in surrounding selectively logged areas. Former logging roads had a significantly higher soil pH than surrounding areas and, due to the direction of construction, a significantly more southerly aspect. Fourteen years after harvest, logging roads continued to provide this aggressive exotic with superior habitat for establishment and growth.     

Oculo-facio-cardio-dental syndrome in a girl and her mother

Congenital heart defects are known to be associated with facial dysmorphism and other congenital anomalies. Oculo-facio-cardio-dental (OFCD) syndrome is one such rare multiple congenital anomaly syndrome inherited as an X-linked dominant condition characterized by congenital cataracts, multiple minor facial dysmorphic features, congenital heart defects and dental anomalies. It is unrecognized by many medical and dental professionals. Only 21 cases have been reported so far. This syndrome is often misrecognized as rubella embryopathy because of association of congenital cataract with cardiac anomalies. It is usually the orthodontists who diagnose the syndrome based on typical findings on dental panoramic radiographs. But we suspected our patient to be having OFCD syndrome based on typical facial dysmorphism, ocular and cardiac defects, and finally it was confirmed after noticing typical dental radiographic findings.     

Disparate distribution patterns between canopy and subcanopy life-forms in two temperate North American forests

Quantitative vegetational data of canopy and woody subcanopy species (two life-forms adapted to occupy different strata at maturity) were compared with data collected in two temperate forest ecosystems to determine whether they exhibit a similar pattern of distribution. Tidal freshwater swamps (21 stands) and southern Appalachian forests (19 stands) were examined from data obtained using identical sampling methods. Separate structural analyses of the canopy, sapling, and subcanopy species were compared using the indirect ordination algorithm Detrended Correspondence Analysis. Environmental measurements collected in each stand were assessed for their relationship to the distribution of stands depicted by the ordination diagrams.Canopy trees and saplings showed a similar pattern of distribution, suggesting that the resource requirements of saplings and canopy-statured adults are similar. In contrast, the subcanopy species (species genetically adapted to an understory existence, i.e., shrubs and small understory trees) of neither ecosystem showed any discernable distributional relationship to the canopy or sapling layers (in tidal swamps, there was no clear way to even segregate subcanopy stands into communities). Environmental gradients associated with the subcanopy ordinations differed from those of the canopy and sapling strata in both forest systems, suggesting that subcanopy species partition different resources than do canopy species.If a lack of similarity in distribution patterns between canopy and subcanopy species is universal in temperate forests, then the common practice of combining sapling and subcanopy species in structural analyses may hinder our understanding of subcanopy structural patterns in forests.     

Pattern of dental eruption,skeletal maturation and stress in a Medieval Population from Sudanese Nubia

The present research represents a comparison of dental and skeletal development as a means for determining nutritional stress in a Medieval Christian population from Nubia’sBatn el Hajar. The sample consists of 21 individuals from an early Christian (c 550–750) and 23 individuals from a late Christian cemetery (c mid-16th century) excavated from the site of Kulubnarti, Sudan. Ages at death ranged from 12 to 23 years. For the combined sample, a large majority (70.5%) of individuals had skeletal ages younger than their dental ages. However, a comparison of those individuals that could be sexed revealed that the pattern was not consistent for males and females. Females showed no difference between skeletal and dental age while males showed significant skeletal retardation. This pattern of sex differences is consistent with that observed for modern living children and subadults experiencing nutritional stress. A comparison by cemetry also suggests a reduction in stress from early to late Christian times with later Christians showing a closer correspondence between skeletal and dental ages. While not statistically significant, this apparent reduction is consistent with previous research on the subadult remains.