Enamel microstructure and molar wear in the greater galago,Otolemur crassicaudatus (mammalia,primates)

This study describes the molar enamel microstructure of the greater galago, based on SEM study of four individuals. Galago molar enamel consists primarily of radially oriented Pattern 1 prisms. However, the most superficial enamel is characterized by regions of poorly developed prisms or nonprismatic enamel, and Pattern 3 prisms can be found at depths intermediate and deep to the enamel surface. Orientations of prism long axes relative to wear surfaces differ among functionally distinct regions (cuspal facets, Phase I/II facets, and crushing basins). Consequently, orientations of enamel crystallites relative to these surfaces also differ. Because crystallites are the structural unit involved in enamel abrasion, these differences in orientation may have important effects on molar wear patterns. Crystallite orientations differ most between cuspal facets and Phase I/II facet surfaces. Cuspal facets are characterized by near surface-parallel interprismatic and surface-oblique prismatic crystallites. Previous experimental studies suggest that this arrangement is most resistant to wear when surface-normal (compressive) loads predominate. In contrast, prismatic and interprismatic crystallites intercept Phase I/II facet surfaces obliquely, an arrangement expected to resist abrasion when surface-parallel (shearing) loads predominate. Superficial enamel is preserved at most basin surfaces, indicating that these regions are subject to comparatively little abrasive wear. These results support the hypothesis that galago occlusal enamel is organized so as to resist abrasion of different functional regions, a property that may prove important in maintaining functional efficiency. However, this largely reflects constraints of occlusal topography on a microstructure typical of many mammals and thus does not appear to represent a structural innovation. © 1993 Wiley-Liss, Inc.     

Enamel ultrastructure and masticatory function in molars of the American opossum, Didelphis virginiana

Maxillary and mandibular molars of the American opossum, Didelphis virginiana L., were viewed in the scanning electron microscope (SEM) after acid-etching or after cutting and acid-etching. Observations were made on enamel prism patterns as they relate to functional properties of the tooth at a particular site. Molars at different stages of wear were also observed under a dissecting microscope; worn surfaces were correlated with function and enamel ultrastructure. Pounding surfaces of molar cusps wear more rapidly than near-vertical shearing surfaces or crushing basins (i.e. the trigon and talonid basin). Pounding surfaces are subjected to abrasion by food and arc not normally involved in tooth-tooth contact. Near-vertical shearing surfaces and basins used for crushing do experience tooth-tooth contact, but are surprisingly more resistant to wear. Prisms at pounding sites approach the occlusal surface at a near 90° angle and are surrounded with very thick interprismatic (IP) enamel parallel to the occlusal surface of the tooth. The pounding pattern is present at tips of cusps and at occlusal surfaces of ridges of the tooth. At near-vertical shearing surfaces, the prisms approach the outer surface obliquely and are surrounded with IP crystals which are perpendicular to the vertical surface. The angle between prismatic and IP enamel in these patterns is 60–90° in a cervical to occlusal direction. In basins of the tooth used principally for crushing and some shearing, IP enamel is perpendicular to the changing slope of the basin and the prisms are usually at a 55–65° angle to the IP enamel. When the pounding and shearing-crushing patterns meet at a ridge, a distinct seam is observed. Pounding forces occur parallel to the long axis of the prisms and perpendicular to the thick IP enamel (i.e. perpendicular to the long axis of the IP crystals) lying on either side of the prisms. Shearing and crushing forces occur at an oblique angle to the prism, and interprismatic enamel is more evenly distributed about the prism. A spiral pattern is found at the bottoms of the trigon and talonid basins, but not at the bottom of the trigonid which is a non-occluding basin. It is concluded that the differential rates of wear of the enamel surfaces are necessary in maintaining the sharp cutting edges and effective crushing basins of the tribosphenic molar, and the ultrastructural arrangements of the enamel prisms are of functional significance.     

Taxonomie du grand canidé de la grotte du Vallonnet (Roquebrune-Cap-Martin, Alpes-Maritimes, France)

The large canid of Vallonnet cave belongs to Xenocyon lycaonoides. Its remains are similar to the Xenocyon from Untermassfeld in Germany. X. Lycaonoides, and evoluated form of the Xenocyon genus, is characteristic of the second half of the Lower Pleistocene. The genus Xenocyon may be the ancestor of both Cuon and Lycaon.     

L'Aurignacien et le Gravettien ancien de la grotte Paglicci au Mont Gargano

The author illustrates, in a very synthetical way, Aurignacian and early Gravettian lithic industry from Paglicci Cave (Mount Gargano, South Italy), found during excavations carried out by University of Siena in the Eighties-Nineties. Layer 24 contains Aurignacian industries and is constituted by a fine silty-sandy sediment. The faunal remains from layer 24, dominated by Equus asinus, indicate a dry-temperate phase which on the basis of ¹⁴C dates, would be identified with the Arcy. Lithic industry contains numerous marginally backed bladelets and microbladelets Dufour like that, in the higher level evolve into a special type (denominated “PA 24 A1”). The early Gravettian occupies the overlying layers 23 and 22 that are rich in rough stones and blocks and contain more or less cold faunal remains (at first dominated by Capra ibex, subsequently Bos primigenius becomes abundant): the ¹⁴C dating insert them in a phase between Arcy and Tursac. Lithic industry includes a great number of La Gravette backed points and especially microgravette backed points. Some probable fléchettes are also present but unfortunately they are fragmented.     

Aux origines de la Spiritualité : la notion de transcendance au Paléolithique

In a previous note we presented the expression of the late paleolithic spirituality (Welté and Lambert, 2004). A special analytic grid was used as a possible tool for a demonstration. We separeted rationality from metaphysic; notions which are linked with dialectic relations between necessity (daily constraints), thought, action and evolution in the paleolithic period. Starting from the no direct material activities like burials, funeral materials and art, we purpose now that such notions existed before the upper Paleolithic. We infer that a privilegious set of interactions between the animal and the human appeared early in the thought of the people, before the upper Paleolithic. A metaphysic univers forced itself upon them as an evident “anti-world” which is the symmetric shape of the real and tangible world. In such a context, the social system(s) could not discard these duality.     

Apport des grands mammifères de la grotte du Vallonnet (Roquebrune-Cap-Martin, Alpes-Maritimes, France) à la connaissance du cadre biochronologique de la seconde moitié du Pléistocène inférieur d'Europe

The large mammals of Vallonnet cave, found into a level contemporary of Jaramillo event, are characteristics of the second half of the Lower Pleistocene. Some differences with the faunas of Fuente Nueva 3 and Barranco Leon, in Spain, which datation is the middle of the Lower Pleistocene, show that Vallonnet is younger. On the other hand, the differences are clear with Soleilhac faunas, which datation is the beginning of the middle Pleistocene.     

Inhibition de l'adhérence de Porphyromonas gingivalis sur la surface de titane greffé de poly(styrène sulfonate de sodium)

Dental implant-associated infections as peri-implantitis represent one of the major causes of osteointegration failures of oral implants. Adhesion of Porphyromonas gingivalis, one of the bacterial strains mainly involved in such infections, is tightly dependent on the topographical and/or physico-chemical properties of the implant surfaces. As a matter of fact, we showed that the grafting of one bioactive polymer such as poly(sodium styrene sulfonate) onto titanium implant surfaces allowed a sensitive decrease of Staphylococcus aureus adhesion (> 40%). The aim of the study consists in evaluating the adhesion of P. gingivalis onto titanium surfaces grafted with poly(sodium stryrene sulfonate) in order to elaborate implants exhibiting appropriate inhibiting properties towards the adhesion of periodontal pathogens. The grafting of poly(sodium stryrene sulfonate) onto titanium surfaces is carried out in two steps: chemical oxydation of titanium to initiate radical species then grafting of poly(sodium stryrene sulfonate) by radical polymerization. Chemical characterization of the surfaces is achieved by Fourier transformed infrared spectroscopy (FTIR). Bacterial adhesion was studied on grafted and non grafted (control) titanium surfaces, preadsorbed or not by plasmatic proteins. Protein adsorption as well as bacteria adhesion is followed by fluorescence spectroscopy by using proteins or bacteria previously labelled with fluorescence probes; the quantification of adsorption and bacteria adhesion are performed by image analysis. Results showed that protein adsorption is more important (~3 times) and that P. gingivalis adhesion is strongly inhibited (~73%) onto poly(sodium styrene sulfonate) grafted surfaces when compared to titanium control. Moreover, the inhibition of bacterial adhesion on grafted surfaces preadsorbed with plasma proteins is comparable to that observed on grafted surfaces preadsorbed with fibronectin. In conclusion, the obtained results evidenced that the grafting of titanium surface by poly(sodium styrene sulfonate) led to significant inhibition of P. gingivalis adhesion and that this inhibitory activity involved adsorbed proteins. Poly(sodium styrene sulfonate) grafted titanium surfaces present a high interest for the elaboration of oral implants in various clinical dental applications.     

Development, structure and function of rhinoceros enamel

Vertical enamel prism decussation in the inner-layer enamel of rhinoceroses occurs as the result of vertical translation, in opposite senses, of zones of ameloblasts, which begins very shortly after amelogenesis commences at the enamel-dentine junction. Prisms in the centre of the decussating zones are stacked in the Pattern 3 arrangement. Zone boundary prisms adopt intermediate orientations, are locally nearly perpendicular to the enamel surface, and have a cylindrical, Pattern 1 cross-section. Decussation also continues in the outer-layer enamel, but the prisms all have occlusal-going courses: the occlusal-going zones of the inner enamel continue as the more occlusally oriented zones of the outer layer. Abrasion resistance to diamond polishing and soft abrasive projectile erosion (air-polishing with NaHCOs) and resistance to ion beam erosion is greater with distance from the nearest prism boundary discontinuity. Polished surface areas containing longitudinally sectioned prisms are more prone to 'air-polishing' and 'airbrading' erosion than areas with transversely sectioned prisms. These observed relationships fully explain the relief developed at natural wear surfaces.     

Small and large mammals from the Ciota Ciara cave (Borgosesia,Vercelli, Italy): An Isotope Stage 5 assemblage

The Ciota Ciara cave is located within the Monte Fenera karst system (Borgosesia, Vercelli, Italy) at 670 m a.s.l. The cave entrance presents a deposit with Mousterian quartz and flint industry. The faunal remains from Stratigraphic Units 13, 14 and 103 are the subject of this work and are presented here as a whole for the first time. The large mammal assemblage is dominated by Ursus spelaeus. In addition, a few remains of carnivores such as Panthera leo spelaea, Panthera pardus, Meles meles have been found together with ungulates such as Cervus elaphus and Rupicapra rupicapra. The small mammal assemblage is characterized by a high biodiversity, especially in bats, by the dominance of Clethrionomys glareolus and by a relatively large number of Pliomys coronensis, a species that seems to disappear from the Italian Peninsula at the end of Marine Isotope Stage 5 or during the beginning of MIS 4. The changes in frequency of the small and large mammals between the two S.U. suggest a change from a relatively cold-humid (S.U. 14) to a warmer-still humid climate (S.U. 13). Although no radiometric dates are available yet, the small and large mammal assemblages, the presence of Pliomys coronensis and the climate change inferred by the variation of the small mammal frequencies allow us to correlate these two units of the Ciota Ciara cave to a relatively warm moment of Marine Isotope Stage 5.     

The epithelial genotype controls the pattern of extracellular enamel prism formation

Abstract. Enamel formation in the developing tooth organ is the product of epithelial-mesenchymal interactions which result in the differentiation of ameloblasts, the secretion of enamel proteins, and the production of a highly organized extracellular matrix. The three-dimensional organization of enamel prisms is species-specific: irregular polygonshaped in rabbit and rectangular-shaped in mouse. We designed experiments to test the hypothesis that three-dimensional organization of enamel prism formation is genetically determined by epithelium; the prediction being that speciesspecific enamel prism pattern formation is expressed independent of mesenchymal instructions. Our strategy employs scanning electron microscopy to examine enamel prism patterns formed during rabbit and mouse tooth morphogenesis in situ and in vitro, and to then determine the specific tissue type required for regulating these patterns using heterotypic tissue recombinations. Morphometric analyses demonstrated that cap stage tooth organs cultured on the chick chorioallantoic membrane (CAM) formed enamel prisms equivalent to prism patterns observed for in situ controls. Heterotypic tissue recombinations, using cap stage molar organs, formed rabbit-like prisms with rabbit epithelium/mouse mesenchyme, and mouse-like prisms with mouse epithelium/rabbit mesenchyme. These results indicate that dental papilla mesenchyme has no apparent influence on enamel prism pattern formation. Enamel prism pattern appears to be genetically regulated by the inner enamel epithelium.     

On the nature of the opaque and translucent enamel regions of some macropodinae (Macropus giganteus,Wallabia bicolor and Peradorcas concinna)

Summary Teeth of three macropod species, M. giganteus, W. bicolor and P. concinna, have been studied using the techniques of light microscopy, scanning- and transmission-electron microscopy and hardness measurement. Light microscope observations showed that the teeth of these species had a translucent enamel region close to the dentine and an outer opaque enamel region at the tooth's surface. These regions were not related to the presence or absence of tubules which are a characteristic feature of marsupial enamel. Hardness tests showed that the opaque enamel was softer than the translucent enamel. Scanning electron microscope observations revealed that there was no correlation between any particular prism packing or orientation and the opaque and translucent enamel regions. Transmission electron microscope observations showed that the translucent enamel region consisted of well defined prisms and well packed, lath-like crystals, whereas the opaque enamel was disrupted by voids (which ranged in size from enlarged micropores to about 2 m in diameter in extreme cases) between crystals and some randomly oriented, loosely packed crystals. This disruption within the opaque enamel region was more common at prism boundaries but pockets of disrupted enamel were also found within prisms and interprismatic regions. The opacity of the enamel was caused by scattering of light from the voids. The ultrastructure of the opaque enamel region indicated that this region was hypomineralized; hardness tests and polarized light microscope observations were consistent with these results.     

Enamel microstructure in lemuridae (mammalia,primates): Assessment of variability

This study describes the molar enamel microstructure of seven lemurid primates: Hapalemur griseus, Varecia variegata, Lemur catta, Lemur macaco, Lemur fulvus rufus, Lemur fulvus fulvus, and Lemur fulvus albifrons. Contrary to earlier accounts, which reported little or no prism decussation in lemurid enamel, both Lemur and Varecia molars contain a prominent inner layer of decussating prisms (Hunter-Schreger bands), in addition to an outer radial prism layer, and a thin, nonprismatic enamel surface layer. In contrast, Hapalemur enamel consists entirely of radial and, near the surface, nonprismatic enamel. In addition, for all species, prism packing patterns differ according to depth from the tooth surface, and for all species but Varecia (which also has the thinnest enamel of any lemurid), average prism area increases from the enamel-dentine junction to the surface; this may be a developmental solution to the problem of accommodating a larger outer surface area with enamel deposited from a fixed number of cells. Finally, contradicting some previous reports, Pattern 1 prisms predominate only in the most superficial prismatic enamel. In the deeper enamel, prism cross-sections include both closed (Pattern 1) and arc-shaped (Pattern 2 or, most commonly, Pattern 3). This sequence of depth-related pattern change is repeated in all taxa. It should also be emphasized that all taxa can exhibit all three prism patterns in their mature enamel. The high degree of quantitative and qualitative variation in prism size, shape, and packing suggests that these features should be used cautiously in phylogenetic studies. Hapalemur is distinguished from the other lemurids by unique, medially constricted or rectangular prism cross-sections at an intermediate depth and the absence of prism decussation, but, without further assessment of character polarity, these differences do not clarify lemurid phylogenetic relations. Some characters of enamel microstructure may represent synapomorphies of Lemuridae, or of clades within Lemuridae, but homoplasy is likely to be common. Homoplasy of enamel characters may reflect functional constraints. © 1994 Wiley-Liss, Inc.     

Fibrils in marsupial enamel tubules

Summary Serial etching of cross-sectioned prisms in undecalcified adult marsupial enamel from different species, revealed distinct cylindrical acid-resistant fibrils that were demonstrable by light microscopy and by scanning electron microscopy. No fibrils were found in the enamel of Vombatus.The fibrils and the organic matrix in the remainder of the enamel stain differently. The fibrils project from the center of prisms or the borderline between prisms and interprismatic substance.It is concluded that the fibrils are chemically different from the organic matrix in the enamel, that they constitute the compact, homogenous, and morphologically well defined organic contents of the tubules in adult marsupial enamel.Since most of the material was obtained from dry museum crania, it is concluded that the fibrils are not destroyed by prolonged drying.The scanning electron micrographs were taken at the Electron Microscopical Unit for Biological Sciences, Oslo, Norway.     

Enamel Structure of Cuvieronius hyodon (Proboscidea, Gomphotheriidae) with a Discussion on Enamel Evolution in Elephantoids

Dental material of the South American elephantoid Cuvieronius hyodon from the Late Pleistocene of the Tarija Basin, Bolivia was sampled for a comprehensive analysis of the microstructure of the enamel. To examine variability at the dentition level, enamel samples of the upper incisor, second deciduous premolar, and molars were sectioned. The incisor and cheek teeth enamel is compared to that of other proboscideans in order to reveal phylogenetically and functional informative features useful to reconstruct the evolution of elephantoid enamel. Studies of the adaptations and evolution of proboscidean enamel have focused so far on molars. Nevertheless, given the possibility of an independent evolution of the enamel at different tooth positions, the variation of the enamel throughout the dentition needs to be taken into consideration when using enamel microstructural characters to infer proboscidean diversity and phylogeny. The results obtained from this study demonstrate the generality, among elephantoids, of the basic microstructural features of Cuvieronius hyodon enamel, allowing the characterization of the Elephantoid Enamel (EE). The differentiation between incisor and molar enamel seen in elephantoids is shown to represent a primitive elephantiform trait, as it also occurs in Phiomia. The three-layered enamel of the cheek teeth appears as the sole synapomorphy of the Elephantoidea, though the character might be homoplastic within the Proboscidea. Characters of the prisms cross-section might be used, on the other hand, to define less inclusive clades within the Elephantoidea.     

大熊猫臼齿釉质的超微结构和氨基酸组成

大熊猫臼齿釉质的超微结构特征主要是施氏明暗带的宽度一般由8—15条釉柱组成;釉柱的横切面一般呈六角形或四角形,由里向外,釉柱的直径逐渐增大。在靠近釉牙本质界处,釉柱数量逐渐减少,有时甚至完全缺失,形成无釉柱结构的釉质。大熊猫臼齿釉质的氨基酸组成主要以甘氨酸,丙氨酸,谷氨酸,天冬氨酸和亮氨酸的含量为最高,而蛋氨酸,胱氨酸和酪氨酸的含量为最低。另外,还含有少量的羟脯氨酸。这种组成模式一般与人类和其它哺乳动物牙齿釉质的氨基酸组成相类似。     

Electron microscopic investigation relating the occlusal morphology to the underlying enamel structure of molar teeth of the wombat (Vombatus ursinus)

This investigation relates the occlusal morphology of the continuously growing molars of common wombats (Vombatus ursinus) to the underlying enamel ultrastructure that was investigated using the techniques of light microscopy, scanning electron microscopy, and transmission electron microscopy. The main feature of the occlusal enamel was a prominent ridge, which followed the contour of the dentine-enamel junction (DEJ). It was found that the occlusal morphology depended upon the orientation of the dentinal and enamel tissues, variations in prism orientation, Hunter-Schreger bands (HSB), and presence or absence of cleavage. Cleavage of enamel promoted by sheets of parallel prisms occurred along the face between the DEJ and the ridge, whereas on the face between the ridge and the cementum-enamel junction (CEJ) cleavage was inhibited by HSB. The slope of the latter face was mainly due to a decrease in wear resistance going from the ridge, where prisms were intercepted transversely, toward the CEJ, where they were intercepted obliquely. Occasionally small surface undulations were observed on the face between the ridge and the CEJ. These undulations were found to correspond to gradually decussating enamel regions. The pronounced cleavage of enamel parallel to the face between the DEJ and the ridge played an important role in conferring on the continuously growing molars a distinct property to develop and maintain a self-sharpening ridge throughout the life of the tooth.     

Ultrastructure of enamel and dentine in extant dolphins (Cetacea: Delphinoidea and Inioidea)

Longitudinal and cross sections of teeth from 17 species of the Recent dolphins (Delphinoidea and Inioidea) were examined under scanning electron microscope to study the arrangement and ultrastructure of dental tissues with reference to phylogenetic and functional constraints. For most species, enamel had a simple bi-layered structure of radial enamel and an outer layer of prismless enamel. The outer prismless layer varied from 5 to 30 % of enamel thickness. The enamel of Burmeister’s porpoise (Phocoena spinipinnis) was entirely prismless. The prisms had an open sheath; tubules and tuft-like structures were common at the enamel-dentine junction. Cetacean dentine was characterized by irregularly distributed dentinal tubules in a relatively homogenous dentinal matrix. Radial enamel was observed in all Delphinoidea and in the franciscana (Pontoporia blainvillei), whereas the Amazon river dolphin (Inia geoffrensis) had prisms organized in Hunter–Schreger bands. HSB in enamel are regarded as a device for resisting propagation of cracks. These may occur due to increased functional demands, possibly related to the hardness of the species diet. Simplification in tooth shape and reduced biomechanical demands plausibly explain the primitive radial organization among delphinoids and Pontoporia. The HSB structure in the Amazon river dolphin, similar to those of extinct archaeocetes, seems to have secondary functional implications. However, the distribution of HSB in more-basal odontocetes is too poorly known to judge whether the HSB of Inia are a retained plesiomorphic feature or convergence.     

Enamel microarchitecture of a tribosphenic molar

The tribosphenic molar is a dental apomorphy of mammals and the molar type from which all derived types originated. Its enamel coat is expected to be ancestral: a thin, evenly distributed layer of radial prismatic enamel. In the bat Myotis myotis, we reinvestigated the 3D architecture of the dental enamel using serial sectioning combined with scanning electron microscopy analyses, biometrics of enamel prisms and crystallites, and X‐ray diffraction. We found distinct heterotopies in enamel thickness (thick enamel on the convex sides of the crests, thin on the concave ones), angularity of enamel prisms, and in distribution of particular enamel types (prismatic, interprismatic, aprismatic) and demonstrated structural relations of these heterotopies to the cusp and crest organization of the tribosphenic molar. X‐ray diffraction demonstrated that the crystallites composing the enamel are actually the aggregates of much smaller primary crystallites. The differences among particular enamel types in degree of crystallite aggregation and the variation in structural microstrain of the primary crystallites (depending upon the duration and the mechanical context of mineralization) represent factors not fully understood as yet that may contribute to the complexity of enamel microarchitecture in a significant way. J. Morphol., 2010. © 2010 Wiley‐Liss, Inc.     

Les faunes de grands mammifères de la Caune de l'Arago (Tautavel) dans le cadre biochronologique des faunes du Pléistocène moyen italien

The fossiliferous levels of Caune de l'Arago supply a useful tool to investigate the relationships between faunal renewals and climate changes in a restricted area during the Middle Pleistocene. On the other hand the Italian fossil assemblages of the middle Galerian testified changes of palaeoenvironmental conditions. A biochronologic and palaeoecologic comparison among large mammalian faunas of these quite different Mediterranean regions have been performed in the aim to value possible vicariance of taxa and differences of faunal renewal dynamic during the Middle Pleistocene. After the results of our analysis we can correlate the faunal assemblages from the “Complexe moyen, ensemble stratigraphique I”, “Complexe moyen, ensembles stratigraphiques II and III”, “Complexe supérieur, sols A and B” of Caune de L'Arago sedimentary succession with the Italian Isernia (middle Galerian), Fontana Ranuccio (late Galerian) and Torre in Pietra (early Aurelian) faunal units (FUs) respectively. The French faunal assemblages were characterised by the absence of browsers and, conversely, by the presence of boreal taxa, mainly grazers, that were rare or never occurred in Italy. Accordingly, at no one Italian faunal complex, as expected, we can find any indication of continental cold climatic condition as showed by the faunal complexes of the Caune de l'Arago. Nevertheless, the major climate changes characterising the Middle Pleistocene can be detected in both regions. During the span time of Isernia FU, the temperature was at its lowest and arid conditions prevailed, whereas during the following Fontana Ranuccio FU humidity and temperature increased, as is more evident in central Italy local faunas. Moreover, after the similarity analysis, the Visogliano local fauna (North-Eastern Italy) was more related to the French than to the Italian ones. During the late Middle Pleistocene (Torre in Pietra FU) a moderate faunal reconstruction can be detected in both regions. The renewal was linked to climatic modifications taking place in the Mediterranean area approximately around OIS 11/OIS 10 transition, when interstadials became progressively milder and average humidity increased.