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Song Xing, María Martinón-Torres, José María Bermúdez de Castro
This study provides new original data, including the endostructure of most Zhoukoudian H. erectus teeth preserved to date, since the publication of Black in 1927 and Weidenreich in 1937. The new evidence ratifies the similarities of Zhoukoudian with other East Asian mid-Middle Pleistocene hominins such as Hexian and Yiyuan, and allows defining a dental pattern potentially characteristic of this population commonly referred to as classic H. erectus. Given the possible chronological overlaps of classic H. erectus with other archaic Homo, the characterization of this group becomes a key issue when deciphering the taxonomy and evolutionary scenario of the Middle Pleistocene hominins in East Asia...
February 1, 2018: Scientific Reports
Patricia Kahle, Carsten Witzel, Uwe Kierdorf, Kai Frölich, Horst Kierdorf
We studied the spatio-temporal variation of mineral apposition rate (MAR) in postnatally formed coronal dentine of mandibular first molars from Soay sheep repeatedly injected with different fluorochromes. MAR declined along the cuspal to cervical crown axis, and from early to late formed dentine, that is, from the dentine at the enamel-dentine-junction (EDJ) to the dentine adjacent to the dentine-pulp-interface (DPI). Highest mean MARs (about 21 µm/day) were recorded in cuspal dentine formed in the period of 28-42 days after birth...
December 15, 2017: Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology
Debbie Guatelli-Steinberg, James D Pampush, Mackie C O'Hara, Song Xing, W Scott McGraw, Rebecca J Ferrell
Enamel formation front (EFF) angles represent the leading edge of enamel matrix secretion at particular points in time. These angles are influenced by rates of enamel extension (the rates at which tooth crowns grow in height), rates of enamel matrix secretion and the angles that prisms make with the enamel-dentine junction. Previous research suggests, but has not yet established, that these angles reflect aspects of primate biology related to their pace of growth and development, most notably brain and body size...
January 2018: Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology
Alejandra Ortiz, Shara E Bailey, Jean-Jacques Hublin, Matthew M Skinner
Evolutionary studies of mammalian teeth have generally concentrated on the adaptive and functional significance of dental features, whereas the role of development on phenotypic generation and as a source of variation has received comparatively little attention. The present study combines an evolutionary biological framework with state-of-the-art imaging techniques to examine the developmental basis of variation of accessory cusps. Scholars have long used the position and relatedness of cusps to other crown structures as a criterion for differentiating between developmentally homologous and homoplastic features, which can be evaluated with greater accuracy at the enamel-dentine junction (EDJ)...
July 18, 2017: Journal of Anatomy
Lei Pan, John Francis Thackeray, Jean Dumoncel, Clément Zanolli, Anna Oettlé, Frikkie de Beer, Jakobus Hoffman, Benjamin Duployer, Christophe Tenailleau, José Braga
OBJECTIVES: The aim of this study is to compare the degree and patterning of inter- and intra-individual metameric variation in South African australopiths, early Homo and modern humans. Metameric variation likely reflects developmental and taxonomical issues, and could also be used to infer ecological and functional adaptations. However, its patterning along the early hominin postcanine dentition, particularly among South African fossil hominins, remains unexplored. MATERIALS AND METHODS: Using microfocus X-ray computed tomography (µXCT) and geometric morphometric tools, we studied the enamel-dentine junction (EDJ) morphology and we investigated the intra- and inter-individual EDJ metameric variation among eight australopiths and two early Homo specimens from South Africa, as well as 32 modern humans...
August 2017: American Journal of Physical Anthropology
Anna Kallistová, Ivan Horáček, Miroslav Šlouf, Roman Skála, Michaela Fridrichová
Using the distal molar of a minipig as a model, we studied changes in the microstructural characteristics of apatite crystallites during enamel maturation (16-23 months of postnatal age), and their effects upon the mechanical properties of the enamel coat. The slow rate of tooth development in a pig model enabled us to reveal essential heterochronies in particular components of the maturation process. The maturation changes began along the enamel-dentine junction (EDJ) of the trigonid, spreading subsequently to the outer layers of the enamel coat to appear at the surface zone with a 2-month delay...
2017: PloS One
Robert M G Martin, Jean-Jacques Hublin, Philipp Gunz, Matthew M Skinner
This study explores the morphological differences between the enamel-dentine junction (EDJ) of maxillary and mandibular molars of Neanderthals (n = 150) and recent modern humans (n = 106), and between an earlier Neanderthal sample (consisting of Pre-Eemian and Eemian Neanderthals dating to before 115 ka) and a later Neanderthal sample (consisting of Post-Eemian Neanderthals dating to after 115 ka). The EDJ was visualised by segmenting microtomographic scans of each molar. A geometric morphometric methodology compared the positioning of the dentine horns, the shape of the marginal ridge between the dentine horns, and the shape of the cervix...
February 2017: Journal of Human Evolution
Wu Liu, María Martinón-Torres, Yousuke Kaifu, Xiujie Wu, Reiko T Kono, Chun-Hsiang Chang, Pianpian Wei, Song Xing, Wanbo Huang, José María Bermúdez de Castro
OBJECTIVES: This study presents the first detailed morphological description and comparison of a Middle Pleistocene hominin mandibular fragment (PA 831) and associated teeth from the Hexian site in Eastern China. We aim to investigate where the Hexian mandible fits within the genus Homo variability in the light of an increased and better characterized Asian fossils record. METHODS: Comparative samples include Pleistocene Homo mandibles and teeth from Africa, Asia, and Europe, as well as earlier African hominins (Australopithecus and early Homo) and Holocene recent humans...
April 2017: American Journal of Physical Anthropology
Mona Le Luyer, Michael Coquerelle, Stéphane Rottier, Priscilla Bayle
Variations in the dental crown form are widely studied to interpret evolutionary changes in primates as well as to assess affinities among human archeological populations. Compared to external metrics of dental crown size and shape, variables including the internal structures such as enamel thickness, tissue proportions, and the three-dimensional shape of enamel-dentin junction (EDJ), have been described as powerful measurements to study taxonomy, phylogenetic relationships, dietary, and/or developmental patterns...
2016: PloS One
Lei Pan, Jean Dumoncel, Frikkie de Beer, Jakobus Hoffman, John Francis Thackeray, Benjamin Duployer, Christophe Tenailleau, José Braga
The appearance of the earliest members of the genus Homo in South Africa represents a key event in human evolution. Although enamel thickness and enamel dentine junction (EDJ) morphology preserve important information about hominin systematics and dietary adaptation, these features have not been sufficiently studied with regard to early Homo. We used micro-CT to compare enamel thickness and EDJ morphology among the mandibular postcanine dentitions of South African early hominins (N = 30) and extant Homo sapiens (N = 26), with special reference to early members of the genus Homo...
July 2016: Journal of Human Evolution
Carolina Loch, Robert W Boessenecker, Morgan Churchill, Jules Kieser
This study aimed to assess the enamel ultrastructure in modern otariid pinnipeds and in the extinct walrus Pelagiarctos. Teeth of the New Zealand fur seal (Arctocephalus forsteri), sea lion (Phocarctos hookeri), and fossil walrus Pelagiarctos thomasi were embedded, sectioned, etched, and analyzed via scanning electron microscopy. The enamel of NZ otariids and Pelagiarctos was prismatic and moderately thick, measuring 150-450 μm on average. It consisted of transversely oriented Hunter-Schreger bands (HSBs) from the enamel-dentine junction (EDJ) to near the outer surface, where it faded into prismless enamel less than 10 μm thick...
June 2016: Die Naturwissenschaften
Matthew M Skinner, Dorien de Vries, Philipp Gunz, Kornelius Kupczik, R Paul Klassen, Jean-Jacques Hublin, Mirjana Roksandic
The Middle Pleistocene represents a period of critical importance in human evolution, marked by encephalisation and dental reduction, and increasing diversification of temporally and spatially distributed hominin lineages in Africa, Asia and Europe. New specimens, especially from areas less well represented in the fossil record, can inform the debate on morphological changes to the skeleton and teeth and the phylogenetic course of human evolution during this period. The mandible from the cave of Mala Balanica, Serbia has recently been re-dated to at least 400 ka, and its well-preserved dentition presents an excellent opportunity to characterize molar crown morphology at this time period, and re-examine claims for a lack of Neandertal affinities in the specimen...
April 2016: Journal of Human Evolution
Sitthichai Wanachantararak, Orapin Ajcharanukul, Noppakun Vongsavan, Bruce Matthews
OBJECTIVE: To determine if dentine at the enamel-dentine junction (EDJ) in man is more sensitive to hydrostatic pressure stimuli then deeper dentine. DESIGN: Cavities (1mm diam.) were cut at the tips of the buccal and lingual cusps of 8 premolars in 3 subjects (ages: 22-25 years). Both cavities were initially deepened to expose the EDJ then one (the test cavity) was deepened in steps of 0.5mm to a maximum of 2.0 mm below the EDJ. The cavities were tested at each stage, before and after etching, with 5s, hydrostatic pressure stimuli between 400 mm above, and 400 mm below atmospheric...
June 2016: Archives of Oral Biology
S Siddiqui, M Al-Jawad
Enamel is an acellular material formed by the intricate process of amelogenesis. Disruption caused at the initial stages of development, by means of mutations in the ENAM gene encoding the enamelin protein, results in enamel hypoplasia. Little is known about the consequence of ENAM mutation on the enamel structure at a crystallographic level. The aim of this study was to characterize the structure of ENAM-mutated enamel to develop a deeper understanding of the role of enamelin protein during formation with regard to crystal organization...
May 2016: Journal of Dental Research
Jan Kühnisch, Friederike Söchtig, Vinay Pitchika, Rüdiger Laubender, Klaus W Neuhaus, Adrian Lussi, Reinhard Hickel
OBJECTIVES: The aims of this clinical study were to investigate the diagnostic accuracy of near-infrared light transillumination (NILT) as a novel X-ray-free method for proximal dentin caries detection and to compare this method to established diagnostic methods. MATERIALS AND METHODS: A total of 127 interproximal dentin caries lesions without any cavity within visible dentin in posterior teeth from 85 consecutively selected patients were included. Visual and radiographic diagnoses and laser fluorescence measurements were available...
May 2016: Clinical Oral Investigations
Adeline Le Cabec, Nancy Tang, Paul Tafforeau
Quantification of dental long-period growth lines (Retzius lines in enamel and Andresen lines in dentine) and matching of stress patterns (internal accentuated lines and hypoplasias) are used in determining crown formation time and age at death in juvenile fossil hominins. They yield the chronology employed for inferences of life history. Synchrotron virtual histology has been demonstrated as a non-destructive alternative to conventional invasive approaches. Nevertheless, fossil teeth are sometimes poorly preserved or physically inaccessible, preventing observation of the external expression of incremental lines (perikymata and periradicular bands)...
2015: PloS One
Philippe Mondon, Mélanie Hillion, Olivier Peschard, Nada Andre, Thibault Marchand, Emmanuel Doridot, Marc Gj Feuilloley, Cédric Pionneau, Solenne Chardonnet
This study was conducted to establish a new methodology for evaluating elements of dermal extracellular matrix (ECM), of epidermal-dermal junction (EDJ), and effects of molecules which can modulate their synthesis. This methodology is based on matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI). In vivo reflectance confocal microscopy (in vivo RCM) and echography were also used. Using immunohistochemistry methods on explants, age-related modification data were obtained for selected dermal ECM and EDJ proteins (collagen I, collagen IV, collagen VII, collagen XVII, nidogen I, decorin/decorunt) and used as reference for MALDI-MSI studies...
June 2015: Journal of Cosmetic Dermatology
A Y Dagnra, S Dossim, M Salou, T Nyasenu, K Ali-Edje, A Ouro-Médeli, M Doufan, A Ehlan, M Prince-David
PURPOSE: HIV rapid diagnostic tests (RDT) could be greatly contributive for a universal access to HIV diagnosis. However, according to the WHO, these tests need to be assessed before they can be used in routine. METHOD AND RESULTS: We assessed 9 RDT in routine clinical use between 2009 and 2013. The sensitivity and specificity observed for 7 tests were≥99% and≥98%, respectively: FIRST RESPONSE HIV1-2-O PMC Medical, India, GENIE Fast HIV 1-2 and GENIE™ III HIV(1/2) Bio-Rad, France, HIV TRI-DOT+Ag;J...
December 2014: Médecine et Maladies Infectieuses
Clément Zanolli
This contribution investigates the inner organizational pattern (tooth tissue proportions and enamel-dentine junction morphology) of seven Homo erectus permanent molar crowns from the late Lower-early Middle Pleistocene Kabuh Formation of the Sangiran Dome (Central Java, Indonesia). The previous study of their external characteristics confirmed the degree of time-related structural reduction occurred in Javanese H. erectus, and also revealed a combination of nonmetric features which are rare in the Lower and early Middle Pleistocene dental record, but more frequently found in recent humans...
January 2015: American Journal of Physical Anthropology
M Christopher Dean, Helen M Liversidge, Fadil Elamin
BACKGROUND: Being able to estimate the age at death of fossil hominins enables meaningful comparisons of both dental and general growth, past and present. AIM: The aim of this study was to use data for modern permanent canine formation derived from separate histological and radiographic studies to estimate the age at death of an early African Homo erectus specimen (KNM-WT 15 000) with a developing permanent maxillary canine. METHODS: Ground sections of 18 sexed modern human canines were used to reconstruct growth in tooth height along the enamel-dentine junction (EDJ) and onwards into root formation along the cement-dentine junction (CDJ)...
July 2014: Annals of Human Biology
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