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Tooth enamel is the outer covering of tooth crowns, the hardest material in the mammalian body, yet fracture resistant. The extremely high content of 95 wt% calcium phosphate in healthy adult teeth is achieved through mineralization of a proteinaceous matrix that changes in abundance and composition. Enamel-specific proteins and proteases are known to be critical for proper enamel formation. Recent proteomics analyses revealed many other proteins with their roles in enamel formation yet to be unraveled. Although the exact protein composition of healthy tooth enamel is still unknown, it is apparent that compromised enamel deviates in amount and composition of its organic material. Why these differences affect both the mineralization process before tooth eruption and the properties of erupted teeth will become apparent as proteomics protocols are adjusted to the variability between species, tooth size, sample size and ephemeral organic content of forming teeth. This review summarizes the current knowledge and published proteomics data of healthy and diseased tooth enamel, including advancements in forensic applications and disease models in animals. A summary and discussion of the status quo highlights how recent proteomics findings advance our understating of the complexity and temporal changes of extracellular matrix composition during tooth enamel formation., Competing Interests: The authors declare no conflict of interest.

Objectives: To examine the correspondence between histology of defective enamel and documented developmental stressors using a pig proxy; with the ultimate goal of differentiating, within enamel, stressor types including birth, weaning, surgery, and social disruption., Materials and Methods: Lower first molars were removed from five female and four male domestic pigs, thin-sectioned and examined with phase-contrast microscopy for daily and accentuated laminations. Known stressor events include birth; processing (nonanesthetized clipping of needle teeth, tail docking, and castration) within 5 days of birth; weaning in nursery; penned vaccination 2-4 days later; transfer to grower barn; additional vaccination. Timing of accentuated laminations was derived from counts of daily laminations from birth and between accentuated laminations; or, more commonly, from measurements between accentuated laminations divided by average daily lamination width., Results: Acknowledging our small sample, we confirm daily periodicity of laminations in pig enamel. Lamination width varies among sexes (males wider), cusps, crown decile, and enamel depth (wider toward surface). Accentuated laminations occurred at reconstructed median ages of 3.7 days after birth (cf. up to 5 days for "processing"), 19.7 days (cf. 18-25 days for weaning), 4.5 days (cf. 2-4 days for vaccination) and ~39.5 days (cf. 63 days for transfer)., Discussion: Encouragingly, the timing of known stressors (birth, surgical processing, weaning, and vaccination) can be determined with high precision, in good thin sections, from accentuated laminations in pig enamel. Timing of transfer was poorly estimated, likely reflecting lesser severity and the occurrence of undocumented stress events in the nursery., (© 2019 Wiley Periodicals, Inc.)

Linear enamel hypoplasia (LEH), the presence of linear defects of dental enamel formed during periods of growth disruption, is frequently analyzed in physical anthropology as evidence for childhood health in the past. However, a wide variety of methods for identifying and interpreting these defects in archaeological remains exists, preventing easy cross-comparison of results from disparate studies. This article compares a standard approach to identifying LEH using the naked eye to the evidence of growth disruption observed microscopically from the enamel surface. This comparison demonstrates that what is interpreted as evidence of growth disruption microscopically is not uniformly identified with the naked eye, and provides a reference for the level of consistency between the number and timing of defects identified using microscopic versus macroscopic approaches. This is done for different tooth types using a large sample of unworn permanent teeth drawn from several post-medieval London burial assemblages. The resulting schematic diagrams showing where macroscopic methods achieve more or less similar results to microscopic methods are presented here and clearly demonstrate that "naked-eye" methods of identifying growth disruptions do not identify LEH as often as microscopic methods in areas where perikymata are more densely packed., (Copyright © 2013 Wiley Periodicals, Inc.)

This study continues the series of works aimed to evaluate non-metric dental characters in medieval and postmedieval human populations from eastern Romania. In this paper, the frequency and degree of expression of some non-metric traits was analysed in a sample of 115 permanent molars belonging to skeletons of 16th-17th centuries recovered from the archaeological site of Vovidenia Church, in Iasi city, Romania. 14 non-metric traits were followed, but only nine of them were identified and analysed. The lack of the y groove pattern and cusp 5 at the lower second molar were noticed. Also, deflecting wrinkle and enamel extensions represent new traits identified medieval dental materials from the studied area. [ABSTRACT FROM AUTHOR]

Description of morphological dental traits is an important concept within dental anthropology. The aim of this paper is to describe the case of occurrence of the enamel extensions in deciduous teeth in archaeological sample. The case of occurrence of enamel extensions on deciduous teeth from late medieval child's skeletal remains is reported, along with other relevant data. Conclusion is that this might be the first such case described in medieval Bosnian archaeological population. [ABSTRACT FROM AUTHOR]

In 2009, a salvage archaeological excavation in Valle da Gafaria (Lagos, Portugal) brought to light the skeletal remains of 158 African enslaved individuals (15th–17th centuries), from which several presented intentional dental modifications on their anterior dentition. Although this cultural practice may be related to rites of passage, differential status, group identification, mourning, or embellishment, it is not exempt from risk. Among the possible consequences are pulp necrosis, dental caries in the modified surface, loss of masticatory function, and dental enamel hypoplasia in the permanent teeth. A previous study in the Lagos collection already confirmed that anterior modified teeth were significantly more affected by periapical lesions (9.3%) than unmodified teeth (0.4%). Therefore, the aim of this investigation is to analyse the relationship between dental caries and intentional dental modification in the Lagos sample. Eighty‐one individuals were analysed, making a total of 2,285 alveoli and 2,063 teeth (757 anterior and 1,306 posterior). Dental caries was recorded if there was a discernible, even if small, white or brown lesion in the otherwise translucent enamel, or if there was a cavity. Intentional dental modifications were recorded according to their presence and incisal angles removed. Dental caries affected 78 individuals (96.3%) and 1,072 teeth (52.0%). In all, intentional dental modifications were observed in 50 (61.7%) individuals and 203 (27.1%) anterior teeth. Modified teeth were significantly more affected by caries (84.2%) than nonmodified teeth (31.7%). Given that all modifications involved the removal of the mesial and/or distal angles of the teeth, the relationship between these alterations and the presence of caries was investigated. In fact, when modified, mesial and distal contact areas were significantly more affected by caries, although mostly noncavitated, supporting the hypothesis that this cultural practice turns teeth more prone to dental caries. [ABSTRACT FROM AUTHOR]

Within the last two decades, the fields of dental anthropology and bioarchaeology have seen a drastic increase in the number of studies investigating the internal structures of human enamel in archaeological populations. Due to its relatively low cost and preparation time, combined with a high degree of accuracy, destructive histological analysis has become a common methodology in enamel research. However, despite its accuracy and presence within academic literature, institutions often reject applications to perform histological analysis as standard procedure. Most frequently this is justified because destructive analysis negatively impacts future research. As a result, many studies are forced to utilise published data or attempt to access the small number of dental histological slides already in existence. This paper details the processes and procedures followed during histological sampling, with the aim to provide an easily accessible reference for curators allowing them to make more informed decisions regarding requests to conduct histology on samples within their care. Moreover, this paper highlights the preservative methods available to researchers which, when employed, both limit the negative impact to future research and expand the type of material which institutions can provide access to. Access to these new materials provides curators with alternative responses to applications rather than rejecting proposals entirely. Methods include high quality resin casting, which allows for future metric and micro-wear analysis, and digital stitching methods for producing dental cross section databases which institutions can offer access to instead of further destructive sampling. [ABSTRACT FROM AUTHOR]

Enamel hypoplasia is a dental pathology that forms when an individual is exposed to physiological stress in early life while tooth crowns are developing. Biological anthropologists utilize these enamel defects as indicators of growth interruption and interpret them as reflective of factors pertaining to health status and cultural practices that influence health. Over decades of research, numerous studies have noted a pattern in the distribution of linear enamel hypoplasia across the dentition. It is suggested that the anterior dentition presents the highest frequency of defects, followed by the premolars, with molars most rarely exhibiting hypoplasia. This apparent differential susceptibility pattern has resulted in the preferential study of the anterior dentition in anthropology, however little research has been conducted into the validity or cause of this developmental phenomenon. Through examination of the literature, the observed higher frequency of enamel hypoplasia in the anterior dentition substantiates the existence of this differential distribution pattern. Further investigation reveals that the cause of this varying susceptibility has not been sufficiently explored, leading to a number of inconclusive explanations. Examination of these theories - ranging from the chronology of tooth development, specifics of crown morphology, and variations in genetic control - indicate that there is no single causal variable, but that a multitude of factors are responsible. From this research it is apparent that further study is necessary to fully understand why the anterior teeth appear to be more susceptible to hypoplastic defects than their posterior counterparts. [ABSTRACT FROM AUTHOR]

Perikymata, incremental growth lines visible on tooth enamel surfaces, differ in their distribution and number among hominin species, although with overlapping patterns. This study asks: (1) How does the distribution of perikymata along the lateral enamel surface of Homo naledi anterior teeth compare to that of other hominins? (2) When both perikymata distribution and number are analyzed together, how distinct is H. naledi from other hominins? A total of 19 permanent anterior teeth (incisors and canines) of H. naledi were compared, by tooth type, to permanent anterior teeth of other hominins: Australopithecus afarensis , Australopithecus africanus , Paranthropus robustus , Paranthropus boisei , Homo ergaster / Homo erectus , other early Homo , Neandertals, and modern humans, with varying sample sizes. Repeated measures analyses of the percentage of perikymata per decile of reconstructed crown height yielded several statistically significant differences between H. naledi and other hominins. Canonical variates analysis of percentage of perikymata in the cervical half of the crown together with perikymata number revealed that, in 8 of 19 cases, H. naledi teeth were significantly unlikely to be classified as other hominins, while exhibiting least difference from modern humans (especially southern Africans). In a cross-validated analysis, 68% of the H. naledi teeth were classified as such, while 32% were classified as modern human (most often southern African). Of 313 comparative teeth use for this analysis, only 1.9% were classified as H. naledi . What tends to differentiate H. naledi anterior tooth crowns from those of most other hominins, including some modern humans, is strongly skewed perikymata distributions combined with perikymata numbers that fall in the middle to lower ranges of hominin values. H. naledi therefore tends toward a particular combination of these features that is less often seen in other hominins. Implications of these data for the growth and development of H. naledi anterior teeth are considered. [ABSTRACT FROM AUTHOR]

Introduction: Dental morphology is a highly heritable characteristic which is stable with time and has a fairly high state of preservation. Nonmetric dental traits have crucial role in ethnic classifications of a population that helps in forensic racial identification purposes. Aims and Objectives: To determine the frequency and variability of possible nonmetric tooth traits using extracted permanent posterior teeth from Kerala population for discerning racial ethnicity. Materials and Methods: This qualitative, cross-sectional study was carried out using 1743 extracted intact permanent posterior teeth collected from different dental clinics situated all over Kerala. Results: The more common features on premolars were multiple lingual cusps (31.21%), distal accessary ridges (16.28%) and Tom's root (17.9%). In upper first molars, Carabelli trait expression was 17.78% and other common features included metaconulo, cusp 5 and enamel extensions. Conclusion: Posterior tooth traits had variable expression in the study population. Low prevalence rate of Carabelli trait in this study is characteristic of Asian population. This research explored new elements of invaluable tooth traits values to understand racial ethnicity of Kerala population. [ABSTRACT FROM AUTHOR]

Objectives The investigation of the record of growth locked in dental enamel provides a unique opportunity to build a comprehensive picture of growth disruption episodes during childhood. This study presents a new methodological basis for the analysis of enamel growth disruptions (enamel hypoplasia) using incremental microstructures of enamel. Methods A three-dimensional technique based upon use of an Alicona 3D Infinite Focus imaging microscope and software is used to record developmental features in the enamel of human permanent mandibular lateral incisors of one individual from the Neolithic site of Çatalhöyük (Turkey). Using this new technique, perikymata are measured down the longitudinal axis of the crown from the incisal margin to the cervix and perikyma spacing profiles are constructed with this new technique. A mathematical basis for the detection of spacing anomalies, which serve as indicators of enamel hypoplasia is presented based upon these profiles. Results Three clearly delineated defects were identified visually, then matched and confirmed metrically using the enamel surface and perikyma spacing profiles. Discussion Human growth has often been used as an indicator of health in past societies because of developmental sensitivity to fluctuations in nutritional status and disease load. Hence, standardization of furrow-form defect identification is of crucial importance for reducing the amount of current subjectivity in the determination of a threshold for the identification of defects among individuals of past populations. The method presented here, which is based on microscopic images of the tooth crown as well as recorded measurements of incremental structures, represents a combined visual-metric approach using LOWESS residuals, and as such provides a substantial advancement to previous methods. It is therefore recommended that additional studies be carried out with this methodology to determine whether this method improves the reliability of enamel defect identification among individuals recovered from bioarchaeological contexts. [ABSTRACT FROM AUTHOR]

ABSTRACT Objective: Archaeological remains strongly suggest that the Holocene Japanese hunter-gatherers, the Jomon people, utilized terrestrial plants as their primary food source. However, carbon and nitrogen isotope analysis of bone collagen indicates that they primarily exploited marine resources. We hypothesize that this inconsistency stems from the route of protein synthesis and the different proportions of protein-derived carbon in tooth enamel versus bone collagen. Carbon isotope ratios from bone collagen reflect that of dietary protein and may provide a biased signal of diet, whereas isotope ratios from tooth enamel reflect the integrated diet from all macronutrients (carbohydrates, lipids, and proteins). Methods: In order to evaluate the differences in inferred diet between the archaeological evidence and bone collagen isotope data, this study investigated carbon isotopes in Jomon tooth enamel from four coastal sites of the Middle to Late-Final Jomon period (5,000-2,300 years BP). Results: Carbon isotope ratios of human teeth are as depleted as coeval terrestrial mammals, suggesting that C3 plants and terrestrial mammals were major dietary resources for the Jomon people. Dietary dependence on marine resources calculated from enamel was significantly lower than that calculated from bone collagen. The discrepancy in isotopic ratios between enamel and collagen and the nitrogen isotope ratio in collagen shows a negative correlation on individual and population levels, suggesting diets with variable proportions of terrestrial and marine resources. Conclusion: This study highlights the usefulness of coupling tooth enamel and bone collagen in carbon isotopic studies to reconstruct prehistoric human diet. Am J Phys Anthropol 158:300-311, 2015. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

ABSTRACT The frequency and chronological distribution of enamel hypoplasias were assessed in a Roman Period population of the Wielbark culture from Rogowo, northern Poland, dated to the 2nd century ad. Hypoplasias were recorded on permanent incisors, canines, and premolars of 52 skeletons. The position of linear defects on the crown surface was measured and then converted to the age of occurrence using two methods: a conventional method that employs the chart of enamel development for the permanent teeth, constructed by Massler et al. (1941) in Swärdstedt's (1966) modification, and the method by Goodman & Song (1999), which corrects for hidden cuspal enamel. Hypoplastic defects were found in 48.1% of examined cases. Linear defects [linear enamel hypoplasias (LEH)] were observed in 38.5% of individuals and in 22% of investigated teeth. The chronological distribution of LEH according to the conventional method revealed two peaks of defects: one at 2.6-3.0 years of age and the other at 4.1-4.5 years of age. The method that accounts for hidden cuspal enamel also provided two peaks, but they occurred at later ages: 3.0-4.0 and 4.6-5.0 years of age. The prevalence of hypoplasia in the Rogowo population in comparison with other European populations of the Roman Period seems to be rather low for both individuals and teeth affected. This may indicate advantageous living conditions, which are supported by archaeological data that suggest general well-being of the Wielbark people. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The extant mammals have evolved highly diversified diets associated with many specialized morphologies. Two rare diets, termitophagy and vermivory, are characterized by unusual morphological and dental adaptations that have evolved independently in several clades. Termitophagy is known to be associated with increases in tooth number, crown simplification, enamel loss, and the appearance of intermolar diastemata. We observed similar modifications at the species level in vermivorous clades, although interestingly the vermivorous mammals lack secondarily derived tools that compensate for the dentition's reduced function. We argue that the parallel dental changes in these specialists are the result of relaxed selection on occlusal functions of the dentition, which allow a parallel cascade of changes to occur independently in each clade. Comparison of the phenotypes of Rhynchomys, a vermivorous rat, and strains of mice whose ectodysplasin (EDA) pathway has been mutated revealed several shared dental features. Our results point to the likely involvement of this genetic pathway in the rapid, parallel morphological specializations in termitophagous and vermivorous species. We show that diets or feeding mechanisms in other mammals that are linked to decreased reliance on complex can lead to similar cascades of change. [ABSTRACT FROM AUTHOR]

Abstract: The early Middle Pleistocene human fossil assemblage from Tighenif, Algeria, likely samples some among the earliest representatives of the Homo heidelbergensis morph. A previous study of three deciduous molars from this assemblage revealed an inner structural signature (crown tissue proportions and enamel thickness topography) roughly approximating the modern human figures. By using advanced techniques of microtomographic-based 3D virtual imaging and quantitative analysis, we significantly extend here the currently available record to 22 permanent teeth, mostly from the mandibular dentition, and provide the first detailed description of the structural condition characterizing this North African deme near the Lower-Middle Pleistocene boundary. Together with a certain degree of individual variation, the teeth of Tighenif exhibit a structural pattern combining primitive, derived, and unique features. The lower molars display a set of enamel-dentine junction nonmetric traits more frequently found in recent humans than in Neanderthals, but also a blend of Neanderthal- and modern-like characteristics in terms of structural conformation and crown tissue proportions. They also exhibit relatively large pulp cavities, with a rather high root bifurcation and well-separated pulp canals, a pattern more closely approximating the condition reported for Late Pleistocene Aterians. [Copyright &y& Elsevier]

Developmental enamel defects are often used as indicators of general health in past archaeological populations. However, it can be difficult to macroscopically distinguish subtle hypomineralised opacities from post-mortem staining, unrelated to developmental defects. To overcome this difficulty, we have used non-destructive x-ray microtomography to estimate the mineral density of enamel. Using a sample of deciduous teeth from a prehistoric burial site in Northeast Thailand, we demonstrate that it is possible to determine whether observed enamel discolourations were more likely to be true hypomineralised lesions or artefacts occurring as the result of taphonomic effects. The analyses of our sample showed no evidence of hypomineralised areas in teeth with macroscopic discolouration, which had previously been thought, on the basis of macroscopic observation, to be hypomineralisations indicative of growth disruption. Our results demonstrate that x-ray microtomography can be a powerful, non-destructive method for the investigation of the presence and severity of hypomineralisation, and that diagnosis of enamel hypomineralisation based on macroscopic observation of buried teeth should be made with caution. This method makes it possible to identify true dental defects that are indicative of growth disruptions. [ABSTRACT FROM AUTHOR]

Stable carbon and oxygen isotope ratios of tooth enamel provide a means to examine nutritional changes during childhood. To date, such studies have used large enamel samples, often spanning the developmental period of the tooth. This paper reports the results of small samples drilled from first molars and premolars of human teeth from Kaminaljuyu, a Classic period city in highland Guatemala. Carbon isotopes show considerable increase between cuspal and cervical enamel for both teeth, indicating an increase in maize consumption during childhood. Oxygen isotope trends are more variable, and suggest some seasonal fluctuation. While the oxygen isotope data confirm the identification of foreign skeletons among the samples, they illustrate a need for caution when sampling teeth due to variable δ18O composition of enamel within a tooth. [ABSTRACT FROM AUTHOR]

DNA methylation is one of the most studied epigenetic marks in the human genome, with the result that the desire to map the human methylome has driven the development of several methods to map DNA methylation on a genomic scale. Our study presents the first comparison of two of these techniques - the targeted approach of the Infinium HumanMethylation450 BeadChip® with the immunoprecipitation and sequencing-based method, MeDIP-seq. Both methods were initially validated with respect to bisulfite sequencing as the gold standard and then assessed in terms of coverage, resolution and accuracy. The regions of the methylome that can be assayed by both methods and those that can only be assayed by one method were determined and the discovery of differentially methylated regions (DMRs) by both techniques was examined. Our results show that the Infinium HumanMethylation450 BeadChip® and MeDIP-seq show a good positive correlation (Spearman correlation of 0.68) on a genome-wide scale and can both be used successfully to determine differentially methylated loci in RefSeq genes, CpG islands, shores and shelves. MeDIP-seq however, allows a wider interrogation of methylated regions of the human genome, including thousands of non-RefSeq genes and repetitive elements, all of which may be of importance in disease. In our study MeDIP-seq allowed the detection of 15,709 differentially methylated regions, nearly twice as many as the array-based method (8070), which may result in a more comprehensive study of the methylome. [ABSTRACT FROM AUTHOR]

Dental enamel hypoplasia is a developmental defect in enamel caused by physiological stress during dental development. Previous analysis of enamel hypoplasia in sheep has demonstrated that variation in its frequency can be linked to nutrition levels, with animals suffering from malnutrition more susceptible to enamel hypoplasia formation. Variation in enamel hypoplasia frequency has also been linked to climatic and ecological factors, leading to variation in the availability of fodder supplies and, consequently, variation in nutritional intake. In this paper, the occurrence of enamel hypoplasia in two modern sheep populations is, for the first time, correlated with known seasonal physiological and nutritional stress events. Using known age-at-death data, the dental development rates for sheep are reconstructed, allowing the position of enamel hypoplasia on the tooth crown to be linked to known periods of malnutrition and physiological stress. Both populations live under identical climatic conditions but with very different diets. Clear differences are observed between the two populations, with peaks of enamel hypoplasia correlating with different seasonal periods of malnutrition as well as common physiological stressors linked to birth and weaning. This is the first time that a clear correlation has been made between seasonal variation in nutrition and the occurrence of hypoplastic enamel defects in caprine populations. As such, this study provides a baseline from which the nutritional impact of caprine foddering and husbandry practices can be determined in future archaeological studies. [ABSTRACT FROM AUTHOR]

Dental enamel thickness has received considerable attention in ecological models of the adaptive significance of primate morphology. Several authors have theorized that the degree of enamel thickness may reflect selective pressures related to the consumption of fallback foods (dietary items that may require complex processing and/or have low nutritional value) during times of preferred food scarcity. Others have speculated that enamel thickness reflects selection during mastication of foods with particular material properties (i.e., toughness and hardness). Orangutans prefer ripe fruit when available, but show interspecific and sex differences in the consumption of fallback foods (bark, leaves, and figs) and other preferred foods (certain seeds). Bornean orangutans ( Pongo pygmaeus) have also been reported to masticate more mechanically demanding foods than Sumatran orangutans ( Pongo abelii). To test these ecological models, we assessed two-dimensional enamel thickness in orangutan full dentitions using established histological and virtual quantification methods. No significant differences in average enamel thickness (AET) were found between species. We found significant differences in the components of enamel thickness indices between sexes, with males showing greater enamel-dentine junction lengths and dentine core areas, and thus relatively thinner enamel than females. Comparisons of individuals of known sex and species revealed a dentition-wide trend for Bornean females to show greater AET than Sumatran females. Differences between small samples of males were less evident. These data provide only limited support for ecological explanations of enamel thickness patterns within great ape genera. Future studies of dietary ecology and enamel thickness should consider sex differences more systematically. Am J Phys Anthropol, 2012. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Stable isotope analysis of skeletal tissues is widely used in archeology and paleoanthropology to reconstruct diet. In material that is poorly preserved or very old, the tissue of choice is frequently tooth enamel, since this is less susceptible to diagenesis. The relationships between carbon isotope ratios in tooth enamel (δ13Cenamel), bone collagen (δ13Ccollagen), and bone apatite (δ13Cbone apatite) are, however, not well understood. To elucidate these, we have measured all three indicators in archeological humans from the western and southern Cape coastal regions of South Africa. The correlation between δ13Cenamel and δ13Ccollagen is good ( R2 = 0.71 if two outliers are excluded, n = 79). The correlation between δ13Cenamel and δ13Cbone apatite is weaker ( R2= 0.37, n = 33) possibly due to bone diagenesis. No systematic offset between δ13Cbone apatite and δ13Cenamel was observed in this sample of archeological humans. Intertooth comparisons of δ13Cenamel in three individuals showed little variation, despite the different ages of crown formation. Carbon isotope ratios in both enamel and bone collagen are good proxies for δ13Cdiet. Am J Phys Anthropol, 2012. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The documentation of enamel thickness variation across primates is important because enamel thickness has both taxonomic and functional relevance. The Old World monkeys commonly referred to as mangabeys have figured prominently in investigations of feeding ecology and enamel thickness. In this article, we report enamel thickness values for four mangabey taxa ( Cercocebus atys, Cercocebus torquatus, Lophocebus aterrimus, and Lophocebus albigena), offer revised interpretation of the significance of thick enamel in papionin evolution, and place our new data in a broader comparative framework. Our data indicate that all mangabeys have thick enamel and that the values obtained for Cercocebus and Lophocebus equal or exceed those published for most extant non-human primates. In addition, new field data combined with a current reading of the dietary literature indicate that hard foods make up a portion of the diet of every mangabey species sampled to date. Clarification on the relationship between diet and enamel thickness among mangabeys is important not only because of recognition that mangabeys are not a natural group but also because of recent arguments that explain thick enamel as an evolved response to the seasonal consumption of hard foods. Am J Phys Anthropol 147:326-333, 2012. © 2011 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Abstract: The Middle Paleolithic fossil human teeth from Taddeo cave in southwestern Italy were discovered in 1967, but to date only scanty and partially incorrect information has been published about them. The teeth were recovered in a reddish sandy layer from the cave’s floor, which is attributed either to an early phase of Würm I (OIS 5c or 5d) or a transition phase between Würm I and Würm II (OIS 5a). In this paper, we present a revised morphological description and morphometric comparisons of the four dental remains discovered. Apart from a classic morphometric comparison, we also provide a qualitative and quantitative assessment of the internal morphology with the aid of micro-CT imaging. In addition, virtual restoration and matching of adjacent teeth were performed with 3D digital modeling and Computer-Aided Design techniques. Occlusal Fingerprint Analysis was also employed to help correctly identify each tooth. While in the previous studies, Taddeo 1 was considered either an upper right canine or a lower right canine, in the present work it has been definitely identified as lower left canine. Taddeo 2 has been reclassified as a right P4 instead of a right P3. Based on the occlusal and interproximal wear, we have also shown that Taddeo 2 and Taddeo 3 (right M1) belong to the same individual. All of the teeth show characteristic Neanderthal features in crown morphology and fissure pattern. However, although Taddeo 4 shows morphological features typical of Neanderthal M1s, some morphometric results (large enamel thickness, low dentine volume) recall more modern humans than Neanderthals. This result might suggest that, at least for lower first molars, the Neanderthal range of variation is large and still not clearly understood. [Copyright &y& Elsevier]

Dental microwear analysts have demonstrated that hard diets leave numerous microscopic pits on occlusal surfaces. The relationship between occlusal pitting and gross macrowear, however, is not well known. The current study seeks to elucidate the relationship between dental microwear and macrowear by determin ing if microscopically pitted teeth are associated with greater expressions of macrowear. This study examined microwear and macrowear on mandibular second molars from 60 prehistoric adult Native Americans representing three dietary regimes (foraging, mixed economy, and agriculture). Initially, two dental microwear feature variables were studied: percentage of pits and mean scratch width. Standard macrowenr scores ranged from 4 to 40. ANOVAs suggested that neither of the microwear variables was affected by age or sex, but age affected macrowear scores. Because of this, the sample had a balanced number of young and old adults (i.e., those below and above skeletal age 35). A Pearson's correlation showed no covariatioa between scratch width and the percentage of pits. Regression analysis indicated that macrowear was not a function of the percentage of pits. However, a significant positive relationship was found between dental macrowear and scratch width. A post priori test found a significant negative relationship between macrowear and the total number of scratches. It is concluded, then, that wide scratches remove more enamel and dentin than do numerous pits, although both cause dental wear. It is suggested here that the term "abrasive" be used to describe those microwear profiles that lead to heavy macrowear and have relatively wide scratches. [ABSTRACT FROM AUTHOR]

Abstract: Amygdalodon patagonicus is the oldest record of Sauropoda from South America and is known from several teeth and fragmentary postcranial remains. Here we describe in detail its dental morphology, characterized by the presence of broad spatulated teeth (with low SI values) and the absence of denticles in their crowns. The enamel bears a particular wrinkling pattern composed only of apicobasally-aligned pits, which are frequently joined to each other by a continuous sulcus. Some worn teeth have large wear-facets that extend over only one of the crown''s edges. This unique combination of characters provides a proper diagnosis for Amygdalodon. Despite the fragmentary available material, Amygdalodon is here interpreted as a non-eusauropod sauropod based on the results of a phylogenetic analysis. The presence of derived dental characters in Amygdalodon, such as the presence of tooth-tooth occlusion, shows several features previously thought to diagnose Eusauropoda or Gravisauria appeared earlier during the early evolution of sauropods. [Copyright &y& Elsevier]

Recent studies have suggested that Neandertals and modern humans differ in the distribution of perikymata (enamel growth increments) over their permanent anterior tooth crowns. In modern humans, perikymata become increasingly more compact toward the cervix than they do in Neandertals. Previous studies have suggested that a more homogeneous distribution of perikymata, like that of Neandertals, characterizes the anterior teeth of Homo heidelbergensis and Homo erectus as well. Here, we investigated whether Qafzeh anterior teeth (N = 14) differ from those of modern southern Africans, northern Europeans, and Alaskans (N = 47-74 depending on tooth type) in the percentage of perikymata present in their cervical halves. Using the normally distributed modern human values for each tooth type, we calculated Z-scores for the 14 Qafzeh teeth. All but two of the 14 Qafzeh teeth had negative Z-scores, meaning that values equal to these would be found in the bottom 50% of the modern human samples. Seven of the 14 would be found in the lowest 5% of the modern human distribution. Qafzeh teeth therefore appear to differ from those of modern humans in the same direction that Neandertals do: with generally lower percentages of perikymata in their cervical regions. The similarity between them appears to represent the retention of a perikymata distribution pattern present in earlier members of the genus Homo, but not generally characteristic of modern humans from diverse regions of the world. [ABSTRACT FROM AUTHOR]

The article compares two methods for estimating chronological age at linear enamel formation on anterior dentition. The conventional approach uses regression equations based on a linear model of tooth growth. The other method is based upon a histologically derived curvilinear model of enamel development.

Background: The ability to form teeth was lost in an ancestor of all modern birds, approximately 100-80 million years ago. However, experiments in chicken have revealed that the oral epithelium can respond to inductive signals from mouse mesenchyme, leading to reactivation of the odontogenic pathway. Recently, tooth germs similar to crocodile rudimentary teeth were found in a chicken mutant. These "chicken teeth" did not develop further, but the question remains whether functional teeth with enamel cap would have been obtained if the experiments had been carried out over a longer time period or if the chicken mutants had survived. The next odontogenetic step would have been tooth differentiation, involving deposition of dental proteins. Results: Using bioinformatics, we assessed the fate of the four dental proteins thought to be specific to enamel (amelogenin, AMEL; ameloblastin, AMBN; enamelin, ENAM) and to dentin (dentin sialophosphoprotein, DSPP) in the chicken genome. Conservation of gene synteny in amniotes allowed definition of target DNA regions in which we searched for sequence similarity. We found the full-length chicken AMEL and the only N-terminal region of DSPP, and both are invalidated genes. AMBN and ENAM disappeared after chromosomal rearrangements occurred in the candidate region in a bird ancestor. Conclusion: These findings not only imply that functional teeth with enamel covering, as present in ancestral Aves, will never be obtained in birds, but they also indicate that these four protein genes were dental specific, at least in the last toothed ancestor of modern birds, a specificity which has been questioned in recent years. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to examine the association between developmental defects in the enamel (DDE) of the primary teeth and low birth weight or prematurity. Methods: A case-control study was carried out in Itajaí, Southern Brazil, involving 3- to 5-year-old children. The case group was composed of 102 children presenting at least 1 dental surface with DDE. The control group comprised 113 children without DDE matched by sex and age and enrolled in the same day care centers. All teeth were clinically examined using the Modified Index of Developmental Defects of Enamel. The outcome variable of the study was DDE in at least 1 dental surface, and the independent variables were: (1) birth weight; (2) gestational age; and (3) breast-feeding. Maternal schooling and health problems of the mother during pregnancy and of the child during the first year of life were collected as potential confounding factors. Simple and conditional multiple logistic regression analyses were performed, providing crude and adjusted odds ratio and 95% confidence intervals. Results: Prematurity (OR=2.6; 95% CI=1.0–6.4) and children who did not breast-feed (OR=3.2; 95% CI=1.2–8.4) were associated with defects in tooth enamel after adjusting for possible confounding variables. Conclusions: In this study, premature children and those who did not breast-feed could be considered at risk for developing defects in tooth enamel. [ABSTRACT FROM AUTHOR]

This study presents an analysis of linear enamel hypoplasias (LEH) and plane-form defects (PFD) in the hominine dental sample from the Sima de los Huesos (SH) Middle Pleistocene site in Atapuerca (Spain). The SH sample comprises 475 teeth, 467 permanent and 8 deciduous, belonging to a minimum of 28 individuals. The method for recording PFD and LEH is discussed, as well as the definition of LEH. The prevalence of LEH and PFD in SH permanent dentition (unilateral total count) is 4.6% (13/280). Only one deciduous tooth (lower dc) showed an enamel disruption. Prevalence by individual ranges from 18.7-30%. The most likely explanation for the relatively low LEH and PFD prevalence in the SH sample suggests that the SH population exhibited a low level of develop- mental stress. The age at occurrence of LEH and PFD was determined by counting the number of perikymata between each lesion and the cervix of the tooth. Assuming a periodicity of nine days for the incremental lines, the majority of LEH in the SH sample occurred during the third year of life and may be related to the metabolic stress associated with weaning. [ABSTRACT FROM AUTHOR]

Repetitive linear enamel hypoplasia (rLEH) is often observed in recent large-bodied apes from Africa and Asia as well as Mid- to Late Miocene sites from Spain to China. The ubiquity and periodicity of rLEH are not understood. Its potential as an ontogenetic marker of developmental stress in threatened species (as well as their ancient relatives) makes rLEH an important if enigmatic problem. We report research designed to show the periodicity of rLEH among West African Pan troglodytes (12 male, 32 female), Gorilla gorilla (10 male, 10 female), and Bornean and Sumatran Pongo pygmaeus (11 male, 9 female, 9 unknown) from collections in Europe. Two methods were employed. In the common chimpanzees and gorillas, the space between adjacent, macroscopically visible LEH grooves on teeth with two or more episodes was expressed as an absolute measure and as a ratio of complete unworn crown height. In the orangutans, the number of perikymata between episode onsets, as well as duration of rLEH, was determined from scanning electron micrographs of casts of incisors and canines. We conclude that stress in the form of LEH commences as early as 2.5 years of age in all taxa and lasts for several years, and even longer in orangutans; the stress is not chronic but episodic; the stressor has a strong tendency to occur in pulses of two occurrences each; and large apes from both land masses exhibit rLEH with an average periodicity of 6 months (or multiples thereof; Sumatran orangutans seem to show only annual stress), but this needs further research. This is supported by evidence of spacing between rLEH as well as perikymata counts. Duration of stress in orangutans averages about 6 weeks. Finally, the semiannual stressor transcends geographic and temporal boundaries, and is attributed to regular moisture cycles associated with the intertropical convergence zone modified by the monsoon. While seasonal cycles can influence both disease and nutritional stress, it is likely the combination of seasonal variation in fruiting cycles with specific stressors (malaria and/or intestinal parasites, especially hookworm) that results in this widespread phenomenon. This seasonal stress is sufficiently common and of long duration (6 weeks on average in orangutans) that we think rLEH may reflect significant stress in recent and, inferentially, fossil apes. Increasing seasonality may have impinged negatively on later Miocene apes, especially if they lacked a clear birth peak or seasonality in their reproductive cycles. [ABSTRACT FROM AUTHOR]

Differentiates male and female and black and white American teeth sizes through the constituent decidous tooth crown components study. Enlarged dentine and pulp dimensions in men; Absence of sexual dimorphism in relation to enamel thickness; Isometrically enlarged dentine and pulp tissues in blacks; Disproportionate marginal enamel thickness among blacks.

This paper describes the hypoplastic defects commonly seen on the surface of ancient human tooth crowns, excavated from archaeological sites, and presents a new method for estimating the ages at which these defects were initiated during life. The method is based upon examination of microscopic incremental structures on the enamel surface and it is possible also to apply it to reconstruction of the sequence and timing of dental crown development. The method of examination is non-destructive and allows full use to be made of the large numbers of complete, unworn dentitions which are found amongst archaeological remains. [ABSTRACT FROM AUTHOR]

Since we have found that conventional methods of dentin apposition measurements are inaccurate, we have devised a three dimensional model. This model allows the investigator to measure dentin apposition volumetrically, and simultaneously consider odontoblast activity and the geometric relationships which influence the configuration of the dentin. [ABSTRACT FROM AUTHOR]

The frequency and form of the middle trigonid crest (MTC) in lower permanent molars is reported for 1,131 dental casts of Bushman (San), Bantu, Solomons, Hawaiians, Pima, Eskimo, Navajo, Chinese, and American whites. The MTC occurs most often on the first molar. We found very little intra-trait variation, so observations were scored on a present-absent basis. The MTC is most frequent in the African samples and rare in those of the other populations. Two reference plaques can be obtained to add to the existing series in the ASU dental anthropology system. © 1993 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

This paper is one in a series which explores the possibility of using the non-destructive CT technique to identify patterns in tooth enamel distribution and structure of hominid molars from Plio-Pleistocene sites in South Africa, notably Swartkrans, Sterkfontein, and Kromdraai. Whereas previous investigators have emphasised gross differences in absolute and relative or average enamel thickness between hominid taxa, the present study highlights differences in enamel thickness over functionally significant regions of the crown. Differences in the distribution of enamel in A. robustus, A. africanus, and Homo sp. are identified through the use of bivariate and multivariate analyses, and are interpreted in terms of dietary regimes. © 1992 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Citrate content was determined in the outer surface enamel of unerupted human teeth. The citrate content of the outer surface enamel of erupted teeth was higher than that of unerupted teeth, suggesting that citrate is absorbed from the oral environment after eruption of the teeth. No inverse correlation was found between the citrate and fluoride content of the surface enamel of erupted teeth. [ABSTRACT FROM AUTHOR]

The article presents abstracts on dental topics including the development of dental enamel, dental research on Tibetans, and the relationship between diet and dental caries incidence.

A conference paper on the dental enamel of ancient American Indians is presented. It discusses enamel defects and fissures found in the teeth of American Indians and examines the causes of these defects. The role of diet in the dental problems such as tooth decay experienced by Indians is also explored.

The surface enamel (∼4 µm) fluoride concentrations of different tooth types (11, 21, 22, 23, 24) were determined in 12-13-year-old children who were life-long residents in a naturally high (3.70 ppm) and in a near optimal (0.62 ppm) fluoride area. Enamel biopsies were taken by means of an acid-etch procedure, and the fluoride levels were measured with an adapted fluoride-ion-selective electrode. The enamel fluoride concentrations were related to the fluoride levels of the drinking water, and it appeared that the enamel fluoride concentrations of the different tooth types (except for the pre-molars) were associated with the length of the pre-eruptive period. In general, for both areas, the mean enamel fluoride concentrations increased from the central incisor to the lateral incisor and were found to be the highest in the canine, while the mean fluoride content of the first pre-molar nearly equaled that of the central incisor. No statistically significant differences (p>0.05) were found between the enamel fluoride concentrations of the different tooth types or the etching depths, from different sexes. [ABSTRACT FROM AUTHOR]