Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 270
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Nature ; 580(7802): 235-238, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32269345

RESUMO

The phylogenetic relationships between hominins of the Early Pleistocene epoch in Eurasia, such as Homo antecessor, and hominins that appear later in the fossil record during the Middle Pleistocene epoch, such as Homo sapiens, are highly debated1-5. For the oldest remains, the molecular study of these relationships is hindered by the degradation of ancient DNA. However, recent research has demonstrated that the analysis of ancient proteins can address this challenge6-8. Here we present the dental enamel proteomes of H. antecessor from Atapuerca (Spain)9,10 and Homo erectus from Dmanisi (Georgia)1, two key fossil assemblages that have a central role in models of Pleistocene hominin morphology, dispersal and divergence. We provide evidence that H. antecessor is a close sister lineage to subsequent Middle and Late Pleistocene hominins, including modern humans, Neanderthals and Denisovans. This placement implies that the modern-like face of H. antecessor-that is, similar to that of modern humans-may have a considerably deep ancestry in the genus Homo, and that the cranial morphology of Neanderthals represents a derived form. By recovering AMELY-specific peptide sequences, we also conclude that the H. antecessor molar fragment from Atapuerca that we analysed belonged to a male individual. Finally, these H. antecessor and H. erectus fossils preserve evidence of enamel proteome phosphorylation and proteolytic digestion that occurred in vivo during tooth formation. Our results provide important insights into the evolutionary relationships between H. antecessor and other hominin groups, and pave the way for future studies using enamel proteomes to investigate hominin biology across the existence of the genus Homo.


Assuntos
Esmalte Dentário/química , Esmalte Dentário/metabolismo , Fósseis , Hominidae , Proteoma/análise , Proteoma/metabolismo , Sequência de Aminoácidos , Animais , República da Geórgia , Humanos , Masculino , Dente Molar/química , Dente Molar/metabolismo , Homem de Neandertal , Fosfoproteínas/análise , Fosfoproteínas/química , Fosfoproteínas/metabolismo , Fosforilação , Filogenia , Proteoma/química , Espanha
2.
Eur J Histochem ; 64(1)2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-32046476

RESUMO

The gene expression and protein synthesis of small leucine-rich proteoglycans (SLRPs), including decorin, biglycan, fibromodulin, and lumican, was analyzed in the context of the hypothesis that they are closely related to tooth formation. In situ hybridization, immunohistochemistry, and organ culture with metabolic labeling of [35S] were carried out in mouse first molar tooth germs of different developmental stages using ICR mice at embryonic day (E) 13.5 to postnatal day (P) 7.0. At the bud and cap stage, decorin mRNA was expressed only in the surrounding mesenchyme, but not within the tooth germ. Biglycan mRNA was then expressed in the condensing mesenchyme and the dental papilla of the tooth germ. At the apposition stage (late bell stage), both decorin and biglycan mRNA were expressed in odontoblasts, resulting in a switch of the pattern of expression within the different stages of odontoblast differentiation. Decorin mRNA was expressed earlier in newly differentiating odontoblasts than biglycan. With odontoblast maturation and dentin formation, decorin mRNA expression was diminished and localized to the newly differentiating odontoblasts at the cervical region. Simultaneously, biglycan mRNA took over and extended its expression throughout the new and mature odontoblasts. Both mRNAs were expressed in the dental pulp underlying the respective odontoblasts. At P7.0, both mRNAs were weakly expressed but maintained their spatial expression patterns. Immunostaining showed that biglycan was localized in the dental papillae and pulp. In addition, all four SLRPs showed clear immunostaining in predentin, although the expressions of fibromodulin and lumican mRNAs were not identified in the tooth germs examined. The organ culture data obtained supported the histological findings that biglycan is more predominant than decorin at the apposition stage. These results were used to identify biglycan as the principal molecule among the SLRPs investigated. Our findings indicate that decorin and biglycan show spatial and temporal differential expressions and play their own tissue-specific roles in tooth development.


Assuntos
Dente Molar/embriologia , Odontogênese/fisiologia , Proteoglicanos Pequenos Ricos em Leucina/metabolismo , Germe de Dente/metabolismo , Animais , Anticorpos/imunologia , Feminino , Expressão Gênica/fisiologia , Imuno-Histoquímica , Camundongos Endogâmicos ICR , Dente Molar/química , Dente Molar/citologia , Odontogênese/genética , Gravidez , RNA Mensageiro/metabolismo , Coelhos , Proteoglicanos Pequenos Ricos em Leucina/genética , Proteoglicanos Pequenos Ricos em Leucina/imunologia , Germe de Dente/química , Germe de Dente/citologia , Germe de Dente/crescimento & desenvolvimento
3.
PLoS One ; 15(1): e0226824, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31929573

RESUMO

Mercury (Hg) and selenium (Se) are contaminants of concern for fish in the Upper Colorado River Basin (UCRB). We explored Hg and Se in fish tissues (2,324 individuals) collected over 50 years (1962-2011) from the UCRB. Samples include native and non-native fish collected from lotic waterbodies spanning 7 major tributaries to the Colorado River. There was little variation of total mercury (THg) in fish assemblages basin-wide and only 13% (272/1959) of individual fish samples exceeded the fish health benchmark (0.27 µg THg/g ww). Most THg exceedances were observed in the White-Yampa tributary whereas the San Juan had the lowest mean THg concentration. Risks associated with THg are species specific with exceedances dominated by Colorado Pikeminnow (mean = 0.38 and standard error ± 0.08 µg THg/g ww) and Roundtail Chub (0.24 ± 0.06 µg THg/g ww). For Se, 48% (827/1720) of all individuals exceeded the fish health benchmark (5.1 µg Se/g dw). The Gunnison river had the most individual exceedances of the Se benchmark (74%) whereas the Dirty Devil had the fewest. We identified that species of management concern accumulate THg and Se to levels above risk thresholds and that fishes of the White-Yampa (THg) and Gunnison (Se) rivers are at the greatest risk in the UCRB.


Assuntos
Peixes , Mercúrio/análise , Selênio/análise , Animais , Monitoramento Ambiental , Peixes/classificação , Modelos Lineares , Dente Molar/química , Estudos Retrospectivos , Rios/química , Sudoeste dos Estados Unidos , Distribuição Tecidual
4.
Methods Mol Biol ; 1922: 267-291, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30838584

RESUMO

X-ray micro CT has become a popular methodology for the nondestructive analysis of dental tissues and has been used extensively in the amelogenesis field. The aim of this chapter is to introduce ImageJ/Fiji to researchers new to CT scanning and the analysis of CT image data. The program can be applied to analyzing X-ray CT images of enamel but can be extrapolated to other tissues as well.


Assuntos
Esmalte Dentário/ultraestrutura , Processamento de Imagem Assistida por Computador/métodos , Software , Microtomografia por Raio-X/métodos , Animais , Densidade Óssea , Esmalte Dentário/química , Aprendizado de Máquina , Mandíbula/química , Mandíbula/ultraestrutura , Camundongos , Minerais/química , Dente Molar/química , Dente Molar/ultraestrutura
5.
Radiat Oncol ; 14(1): 5, 2019 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-30635005

RESUMO

BACKGROUND: Radiation caries is a complication of radiotherapy characterized by enamel erosion and dentin exposure. The mechanisms of characteristic radiation caries formation are not well-understood. The aim of this study was to evaluate the direct radiation-induced effects on dental hard tissue and investigate their role in the formation of radiation caries. METHODS: Sixty non-carious third molars were divided into three groups (n = 20), which would be exposed to 0 Gy, 30 Gy, and 60 Gy radiation, respectively. After radiation, microhardness and elastic modulus were measured at four depths by means of a Vickers microhardness tester and atomic force microscopy (AFM). The microstructure was observed by scanning electron microscopy (SEM). X-ray diffraction and Raman microspectroscopy were used to determine crystal properties and protein/mineral (2931/960 cm- 1) ratios. RESULTS: A statistically significant decrease in microhardness and elastic modulus values 50 µm from the dentino-enamel junction (DEJ) in enamel was revealed in the 30-Gy and 60-Gy groups. With the increasing dose, destruction of interprismatic substance and fissures at the DEJ-adjacent region were found. A greater reduction of crystallinity was revealed in enamel compared with dentin. Raman spectroscopic analysis showed a slight increase of the protein/mineral ratio for enamel following accumulated radiation, while the protein/mineral ratio for dentin was decreased. CONCLUSIONS: Radiation could directly alter the mechanical properties, micro-morphology, crystal properties, and chemical composition of dental hard tissue. The early destruction of DEJ-adjacent enamel, combined with decreased crystallinity of enamel under radiation exposure, may be related to the formation of characteristic radiation caries.


Assuntos
Esmalte Dentário/química , Dentina/química , Raios gama/efeitos adversos , Dente Molar/química , Lesões por Radiação/etiologia , Esmalte Dentário/efeitos da radiação , Dentina/efeitos da radiação , Dureza , Humanos , Dente Molar/efeitos da radiação , Lesões por Radiação/patologia
6.
Proc Natl Acad Sci U S A ; 116(4): 1325-1330, 2019 01 22.
Artigo em Inglês | MEDLINE | ID: mdl-30606800

RESUMO

Recent studies have shown that phytoliths are softer than dental enamel but still act as abrasive agents. Thus, phytolith content should be reflected in dental wear. Because native phytoliths show lower indentation hardness than phytoliths extracted by dry ashing, we propose that the hydration state of plant tissue will also affect dental abrasion. To assess this, we performed a controlled feeding experiment with 36 adult guinea pigs, fed exclusively with three different natural forages: lucerne, timothy grass, and bamboo with distinct phytolith/silica contents (lucerne < grass < bamboo). Each forage was fed in fresh or dried state for 3 weeks. We then performed 3D surface texture analysis (3DST) on the upper fourth premolar. Generally, enamel surface roughness increased with higher forage phytolith/silica content. Additionally, fresh and dry grass feeders displayed differences in wear patterns, with those of fresh grass feeders being similar to fresh and dry lucerne (phytolith-poor) feeders, supporting previous reports that "fresh grass grazers" show less abrasion than unspecialized grazers. Our results demonstrate that not only phytolith content but also properties such as water content can significantly affect plant abrasiveness, even to such an extent that wear patterns characteristic for dietary traits (browser-grazer differences) become indistinguishable.


Assuntos
Dióxido de Silício/química , Água/química , Animais , Esmalte Dentário/química , Dieta/métodos , Feminino , Cobaias , Dureza , Dente Molar/química , Plantas/química , Abrasão Dentária/terapia
7.
Biomed Res Int ; 2018: 2438145, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30306085

RESUMO

Purpose: The aim of this study was to evaluate the influence of multimode MDP-based primers and different application protocols on the bond strength of a representative resin cement to an yttrium stabilized tetragonal zirconia (Y-TZP) ceramic. Materials and Methods: The occlusal dentin from 60 human molars was exposed. The teeth and zirconia cylinders (N = 60) (3 mm of diameter; 4 mm of height) were divided into six groups (n = 10) according to the ceramic surface conditioning: (1) air abraded with SiO2 particles; (2) Z-Prime Plus; (3) air abraded with SiO2 particles + Z-Prime Plus; (4) air abraded with SiO2 particles + All-Bond Universal; (5) air abraded with SiO2 particles + ScotchBond Universal Adhesive; and (6) untreated zirconia. The luting agent (Duo-Link cement) was applied on the treated dentin surface. Specimens were stored in water (37°C, 24 h) and tested in shear bond strength. Data were statistically analyzed using 2-way ANOVA and Post hoc Tukey tests (α = 0.05). Results: Significant effects of ceramic conditioning were found (p < 0.0001). The specimens sandblasted with silica particles followed by the application of Z-Prime Plus or All-Bond Universal presented greater bond strength values. For the untreated zirconia, several specimens failed prematurely prior to testing. Conclusions: Sandblasting with silica particles combined with Z-Prime Plus increased the bond strength.


Assuntos
Cerâmica/química , Cimentos Dentários/química , Dentina/química , Metacrilatos/química , Ítrio/química , Zircônio/química , Materiais Dentários/química , Humanos , Teste de Materiais , Dente Molar/química
8.
Sci Rep ; 8(1): 14052, 2018 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-30232366

RESUMO

This study aims to explore the feeding ecology of two terrestrial papionins, Papio and Theropithecus from the Shungura Formation in Ethiopia, the most complete stratigraphic and paleontological record of the African Plio-Pleistocene. Two aspects were evaluated using Dental Microwear Texture Analysis: differences in diet between the extinct genera and their extant relatives, and any potential dietary fluctuations over time. Amongst more than 2,500 cercopithecid dental remains, 154 Theropithecus molars and 60 Papio molars were considered. Thirty-nine extant wild baboons and 20 wild geladas were also considered. The results show that diets of extinct monkeys from Member G already differed between genera as it is the case for their extant representatives. The shearing facets on the Theropithecus molars display significant variations in microwear textures, suggesting several dietary shifts over time. Two events point to higher intakes of herbaceous monocots (tougher than dicots foliages), at about 2.91 Ma (between members B and C) and at 2.32 Ma (between members E and F). These two events are separated by an inverse trend at about 2.53 Ma (between members C and D). Some of these variations, such as between members E and F are supported by the enamel carbon isotopic composition of herbivorous mammals and with paleovegetation evidence.


Assuntos
Dieta , Dente Molar/ultraestrutura , Papio/fisiologia , Theropithecus/fisiologia , Animais , Evolução Biológica , Isótopos de Carbono/análise , Etiópia , Extinção Biológica , Fósseis , Herbivoria , Dente Molar/química , Papio/anatomia & histologia , Theropithecus/anatomia & histologia
9.
Am J Hum Biol ; 30(5): e23163, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30129288

RESUMO

OBJECTIVES: Creating multi-tooth sequences of micro-sampled stable isotope (SI) analytical data can help track 20+ years of individual dietary history. Inferences about individual and population level behavioral patterns require cross-calibration of the timing of dietary changes recorded by each tooth. Dentin sections from contemporaneous tissues (eg, in M1 and M2) reflect dietary signature for the time of growth. Contemporary sections should produce similar values, allowing alignment of temporally overlapping portions of teeth into multi-tooth sequences. Published methods for determining the ages of incremental sections do not provide guidance for adjustment when poor alignment between individual tooth sequences is encountered. The primary objective is to address this problem; examine cause(s), assess the effects of the standard growth-model on available age-assessment techniques, and provide a viable solution. METHODS: Investigating difficulty in aligning a 3-molar sequence at Shamanka II, an Early Neolithic (7000-5700 BP) Kitoi hunter-gatherer cemetery in Cis-Baikal, Siberia, we employed 10 age assessment models and 13 variants of 2 published growth rate methods on 3 individuals of different age and sex. RESULTS: At Shamanka II, dentin initiation and/or growth rates were different from the mostly European, reference populations used to create published age-estimation/growth rate models. Initiation ages for M2 and M3 were delayed. Root formation rates were on the rapid end of known development parameters. CONCLUSIONS: Age-assessment methods customized to dentin initiation ages and growth parameters of Siberian populations produced a hybrid growth rate model for dentin section ages and improved alignment for multi-tooth SI sequences over published models.


Assuntos
Determinação da Idade pelos Dentes/métodos , Antropologia Física/métodos , Arqueologia/métodos , Dente Molar/química , Adolescente , Adulto , Isótopos de Carbono/análise , Feminino , Crescimento , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Teóricos , Dente Molar/crescimento & desenvolvimento , Isótopos de Nitrogênio/análise , Sibéria
10.
Biomed Res Int ; 2018: 5434609, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29854764

RESUMO

Objective: The aim of this study is to present a new adjustable Cise space maintainer for preventive orthodontic applications. Methods: Stainless steel based new design consists of six main components. In order to understand the major displacement and stress fields, structural analysis for the design is considered by using finite element method. Results: Similar to major displacement at y-axis, critical stresses σx and τxy possess a linear distribution with constant increasing. Additionally, strain energy density (SED) plays an important role to determine critical biting load capacity. Conclusion: Structural analysis shows that the space maintainer is stable and is used for maintaining and/or regaining the space which arouses early loss of molar tooth.


Assuntos
Colagem Dentária/métodos , Resinas Compostas/química , Análise de Elementos Finitos , Humanos , Dente Molar/química , Braquetes Ortodônticos , Aço Inoxidável/química
11.
J Biol Regul Homeost Agents ; 32(2 Suppl. 2): 45-50, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29720330

RESUMO

This blinded trial was conducted to analyze possible correlations between the cervical vertebrae maturation method (CVM) and the mineralization of mandibular teeth as described by Demirjian et al. (TMS). Panoramic and cephalometric radiographs of 500 orthodontic patients were analyzed by two blinded operators. TMS was utilized to analyze mineralization of second molar, second and first premolar and canine on the left side of the mandible; CVM stage was also evaluated. A blinded statistician performed statistical correlations and multiple regression analysis. Significant relations between CVM and TMS stages were identified for each tooth. Significant age differences resulted for CVM, second molar and second premolar (p<0.05). Significant correlations for second molar were observed between TMS D and CVM I-II, TMS G and CVM III, TMS H and CVM V-VI (p less than 0.01). Second molar stage G for both sexes indicates the ongoing of growth spurt. Stage G for boys and stage H for girls correlate significantly with the late part of PGS.


Assuntos
Determinação da Idade pelo Esqueleto , Vértebras Cervicais/crescimento & desenvolvimento , Dente Molar/química , Calcificação de Dente , Cefalometria , Feminino , Humanos , Masculino , Mandíbula
12.
Arch Oral Biol ; 91: 51-56, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29673998

RESUMO

OBJECTIVE: The purpose of this study was to investigate the effects of aqueous solutions of different concentrations of titanium tetrafluoride (TiF4) on dentin matrix stability up to six months. DESIGN: Dentin specimens prepared from fifteen nonerupted molars were demineralized and randomly distributed into groups: 2.5% TiF4, 4% TiF4, 1000 ppm NaF, and control (distilled water). The modulus of elasticity (ME) and dry masses of the dentin matrix were determined at baseline, and up to 6 months following treatment. Collagen solubilization was estimated by hydroxyproline (HYP) quantification in the simulated body fluid used to store the dentin specimens. RESULTS: The 2.5% TiF4 group presented higher ME immediately after treatment, and at 3 and 6 months storage, whereas 4% TiF4 showed higher means at 3 and 6 months (p < 0.001). No significant differences were observed among the groups over time (p = 0.9325). However, the 2.5% TiF4 group showed significantly higher ME than the control group, immediately after treatment. All the groups presented significantly higher mass change immediately, compared with 3 and 6 months (p < 0.0001). Except for the 4% TiF4 group, HYP release was higher in the first quarter (p = 0.0152), when no significant differences were found among the groups. In the second quarter, the means were significantly higher in the 2.5% TiF4 and 4% TiF4 groups. The group treated with 2.5% TiF4 had a statistically higher HYP release than the control group. CONCLUSION: An aqueous solution of 2.5% TiF4 increases the immediate stiffness values, but does not stabilize the collagenous dentin matrix.


Assuntos
Dentina/química , Dentina/efeitos dos fármacos , Fluoretos/administração & dosagem , Fluoretos/farmacologia , Titânio/administração & dosagem , Titânio/farmacologia , Cariostáticos/farmacologia , Módulo de Elasticidade/efeitos dos fármacos , Humanos , Hidroxiprolina , Técnicas In Vitro , Teste de Materiais , Dente Molar/química , Dente Molar/efeitos dos fármacos , Peptídeo Hidrolases/efeitos dos fármacos , Fatores de Tempo , Desmineralização do Dente/tratamento farmacológico
13.
Ann Anat ; 218: 7-17, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29604387

RESUMO

BACKGROUND: The aim was to study differences between crystalline nanostructures from the enamel and dentin of human, bovine, porcine, and ovine species. METHODS: Dentine and enamel fragments extracted from sound human, bovine, porcine and ovine incisors and molars were mechanically ground up to a final particle size of <100µm. Samples were analyzed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). RESULTS: Human enamel (HE) and dentin (HD) showed a-axis and c-axis lengths of the carbonate apatite (CAP) crystal lattice nearer to synthetic hydroxyapatite (SHA), which had the smallest size. Enamel crystal sizes were always higher than those of dentin for all species. HE and HD had the largest crystal, followed by bovine samples. Hydroxyapatites (HAs) in enamel had a higher crystallinity index (CI), CIRietveld and CIFTIR, than the corresponding dentin of the same species. HE and HD had the highest CIs, followed by ovine enamel (OE). The changes in heat capacity that were nearest to values in human teeth during the glass transition (ΔCp) were in porcine specimens. There was a significant direct correlation between the size of the a-axis and the substitution by both type A and B carbonates. The size of the nanocrystals and the crystallinity (CIRietveld y CIFTIR) were significantly and negatively correlated with the proteic phase of all the substrates. There was a strongly positive correlation between the caloric capacity, the CIs and the crystal size and a strongly negative correlation between carbonates type A and B and proteins. CONCLUSIONS: There are differences in the organic and inorganic content of human, bovine, porcine and ovine enamels and dentins which should be taken into account when interpreting the results of studies using animal substrates as substitutes for human material.


Assuntos
Esmalte Dentário/anatomia & histologia , Dentina/anatomia & histologia , Animais , Varredura Diferencial de Calorimetria , Bovinos , Cristalização , Esmalte Dentário/química , Dentina/química , Durapatita/química , Humanos , Incisivo/anatomia & histologia , Incisivo/química , Dente Molar/anatomia & histologia , Dente Molar/química , Tamanho da Partícula , Carneiro Doméstico , Especificidade da Espécie , Espectroscopia de Infravermelho com Transformada de Fourier , Sus scrofa , Suínos , Difração de Raios X
14.
Arch Oral Biol ; 90: 74-79, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29573646

RESUMO

OBJECTIVES: The levels of interleukin-1ß (IL-1ß), nitric oxide (NO), total antioxidant capacity (TAC), and total oxidant status (TOS) in gingival crevicular fluid (GCF) were determined during rapid maxillary expansion (RME) treatment. MATERIALS AND METHODS: Fourteen patients (10-13 years old) were included. A modified hyrax appliance was used for the treatment. After periodontal parameters were recorded, GCF was collected from the first molars at each observation [T1:baseline:14 days after periodontal prophylaxis and instructions; T2:1 day later hyrax inserted, at passive position; T3:1 week later; after the first activation; T4:after 2 × 1/4 activation; T5:after 7 × 1/4 activation; T6:after 14 × 1/4 activation; T7:retention period on the 1 st month; and T8:retention period on the 3rd month]. RESULTS: Although the levels of IL1-ß, NO, and PD increased significantly from T1 to T2, the GI, BOP%, and PI remained unchanged throughout treatment. GCF volume at buccal and palatal surfaces increased significantly from T1 to T4, T6, T7, and T8. The parameters in GCF and TAC levels were not only higher at palatal side in comparison with buccal, but also TOS levels increased at both buccal and palatal sides. CONCLUSIONS: In this study, the differences of oxidative status and IL-1ß levels during RME treatment could be attributable to orthopedic effect of the heavy forces on maxilla and minimal orthodontic forces on teeth applied by the RME apparatus.


Assuntos
Líquido do Sulco Gengival/química , Interleucina-1beta/análise , Oxidantes/metabolismo , Técnica de Expansão Palatina/efeitos adversos , Adolescente , Antioxidantes/análise , Criança , Citocinas/análise , Feminino , Humanos , Masculino , Maxila , Dente Molar/química , Óxido Nítrico/análise , Aparelhos Ortodônticos , Estresse Oxidativo , Periodonto/química , Fatores de Tempo
15.
J Hum Evol ; 114: 118-130, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29447754

RESUMO

The strontium isotopic ratio 87Sr/86Sr has been studied in the Sterkfontein Valley of South Africa to infer both habitat usage and residence for a number of early hominins. This paper examines the existing 87Sr/86Sr data collectively derived from three studies of Paranthropus robustus teeth with the aim of exploring whether the dataset as a whole may provide deeper insight into habitat, mobility, and growth for this species. 87Sr/86Sr from seven Swartkrans Member I third molars varies in a well defined narrow range, and while some canines were consistent with this range, a number of P. robustus canines and first and second molars were not, and therefore represent individuals who had arrived from other localities. A first and third molar 87Sr/86Sr was found to differ in TM1517c, the holotype P. robustus specimen from Kromdraai, suggesting this individual had moved to the locality sometime after the first molar and before the third molar had completely mineralized. While early forming teeth vary widely, the relatively low variation and absence of exogenous 87Sr/86Sr in third molars suggest that these teeth mineralized relatively late when compared to life history events bearing on higher primate residence patterns. The implications for further study of habitat, residence, and growth are discussed.


Assuntos
Ecossistema , Hominidae/fisiologia , Migração Humana , Dente Molar/química , Isótopos de Estrôncio/análise , Migração Animal , Animais , Hominidae/crescimento & desenvolvimento
16.
Caries Res ; 52(4): 303-311, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29408818

RESUMO

The objectives of the study were to quantify the dentine mineral concentration (DMC) in teeth restored conventionally, according to the atraumatic restorative treatment (ART) and ultraconservative (UCT) protocols (open cavities and small ART restorations), and the DMC underneath the open cavities of teeth managed by UCT versus nontreated, open cavities. We studied 50 teeth with restorations/open cavities, 39 restored teeth (9 by conventional restorative treatment [CRT], 17 by ART, and 13 by UCT) and 16 teeth with open cavities. Each restoration/open cavity was scanned using microcomputed tomography, with 3 hydroxyapatite disks with respective densities of 1.24, 1.33, and 1.57 g/cm3 as a reference. Images were reconstructed and the greyscale images were converted into DMC values. For each restoration/open cavity, 15 measurements of dentine immediately underneath and from the corresponding area in sound dentine were taken. DMC was expressed as a percentage of the DMC of sound dentine. ANOVA and the Student t test were used for statistical analysis. The mean DMC underneath restorations of the ART protocol group (98.93%) was statistically significantly higher than that of the UCT protocol group (91.98%), but not of the CRT protocol group (91.33%). On multiple surfaces, mean DMC in the axial area (94.32%) was statistically significantly higher than in the gingival area (92.80%). The mean DMC of open cavities managed by UCT protocol (89.05%) was statistically significantly higher than in nontreated open cavities (83.90%). In conclusion, a dentine-hypermineralized area underneath ART restorations was observed. Managing open cavities with a toothbrush and fluoride toothpaste (the UCT protocol) resulted in higher mineralized dentine underneath the cavity than in nontreated open cavities.


Assuntos
Cárie Dentária/metabolismo , Cárie Dentária/terapia , Restauração Dentária Permanente/métodos , Dentina/química , Minerais/análise , Dente Molar/química , Dente Decíduo/química , Cariostáticos/administração & dosagem , Criança , Cárie Dentária/diagnóstico por imagem , Durapatita , Fluoretos Tópicos/administração & dosagem , Humanos , Processamento de Imagem Assistida por Computador , Dente Molar/diagnóstico por imagem , Imagens de Fantasmas , Dente Decíduo/diagnóstico por imagem , Escovação Dentária , Microtomografia por Raio-X
17.
J Proteome Res ; 17(3): 1000-1013, 2018 03 02.
Artigo em Inglês | MEDLINE | ID: mdl-29356547

RESUMO

Proteomic analyses are becoming more widely used in archeology not only due to the greater preservation of proteins in ancient specimens than DNA but also because they can offer different information, particularly relating to compositional preservation and potentially a means to estimate biological and geological age. However, it remains unclear to what extent different burial environments impact these aspects of proteome decay. Teeth have to date been much less studied than bone but are ideal to explore how proteins decay with time due to the negligible turnover that occurs in dentine relative to bone. We investigated the proteome variability and deamidation levels of different sections of molar teeth from archeological bovine mandibles as well as their mandibular bone. We obtained a greater yield of proteins from the crown of the teeth but did not find differences between the different molars analyzed within each mandible. We also obtained the best variety of protein from a well-preserved mandible that was not the youngest one in terms of chronological age, showing the influence of the preservation conditions on the final proteomic outcome. Intriguingly, we also noticed an increase in abundance levels of fetuin-A in biologically younger mandibles as reported previously, but the opposite trend in tooth dentine. Interestingly, we observed higher glutamine deamidation levels in teeth from the geologically oldest mandible despite it being the biologically youngest specimen, showing that the archeological age strongly impacts on the level of deamidations observed, much more so than biological aging. This indicates that the glutamine deamidation ratio of selected peptides may act as a good predictor of the relative geochronological age of archeological specimens.


Assuntos
Dentina/química , Mandíbula/química , Dente Molar/química , Preservação Biológica/história , Proteoma/química , Proteômica/métodos , Sequência de Aminoácidos , Animais , Arqueologia , Bovinos , Ontologia Genética , História Antiga , Humanos , Espectrometria de Massas/instrumentação , Espectrometria de Massas/métodos , Anotação de Sequência Molecular , Paleontologia , Proteólise , Proteoma/isolamento & purificação , Proteômica/instrumentação , Fatores de Tempo , alfa-2-Glicoproteína-HS/história , alfa-2-Glicoproteína-HS/isolamento & purificação
18.
Photomed Laser Surg ; 36(12): 647-652, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31697636

RESUMO

Background: Orthodontics of the 21st century requires aesthetic, painless, predictable, and quick treatments. This demand for faster results generated orthodontic movement acceleration protocols (OMAPs); among other OMAPs we present low-level laser (LLL) as a candidate. Objective: To evaluate levels of interleukin (IL)-1, IL-10, and type 1 collagen in the periodontal ligament of first molars of rats subjected to orthodontic traction with and without LLL irradiation, compared with untreated controls (CO), and to evaluate whether the dose of LLL used in this work is eligible as an OMAP. Materials and methods: A total of 35 male Wistar rats were distributed into three groups: group 1 NI (nonirradiated) n = 15, group 2 IR (laser irradiated using 5 J, 177 J/cm2, and 100 mW applied in contact to the vestibular mesial, vestibular distal, and palatal faces of gum tissue around molar region for 50 sec each point, for 3 consecutive days, immediately 24 and 48 h after orthodontic device placement.) n = 15, and group 3 CO n = 5; groups 1 and 2 were subjected to orthodontic force and each group was divided into three subgroups that were sacrificed after 3, 5, and 7 days, IL-1/10 and COL-1 levels were analyzed. Results: In the IR group, levels of IL-1/10 and COL-1 showed peak anticipation after LLL irradiation compared with those in the NI and CO groups. Conclusions: These results can also infer that this dose of LLL can be used as an OMAP.


Assuntos
Terapia a Laser/métodos , Terapia com Luz de Baixa Intensidade/métodos , Técnicas de Movimentação Dentária , Animais , Colágeno Tipo I/análise , Interleucinas/análise , Masculino , Dente Molar/química , Ligamento Periodontal/química , Ratos , Ratos Wistar
19.
J Mech Behav Biomed Mater ; 77: 557-565, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29078196

RESUMO

The importance of the Dentin Enamel Junction (DEJ) to the durability of adhesive bonds to tooth structure is unclear. In fact, no investigation has been reported on contributions of the DEJ to the fatigue resistance of the bonded interface. In this study, the durability of adhesive bonds to tooth structure involving the DEJ was quantified and compared to that of adhesive bonds to enamel only, not including the DEJ. Two different configurations of enamel bonding were considered, including when tensile stress is focused on the outer enamel (occlusal configuration) or the inner decussated enamel (decussated configuration). The resistance to failure for all bonded interfaces was assessed under both static and cyclic loading to failure. Results showed that the durability of the bonded interfaces was primarily a function of their resistance to crack initiation and growth. The bonded interface strength involving the DEJ was significantly (p ≤ 0.05) greater than that of bonds to enamel only with occlusal configuration, under both static and cyclic loading. While the fatigue strength of bonds involving the DEJ was approximately 20% greater than that for enamel bonds with occlusal configuration (7.7MPa) it was lower than that of enamel with the decussated configuration. The DEJ deterred cracks from extending readily into the dentin but it did not prevent fatigue failure. These results suggest that the durability of bonds to enamel are most dependent on the enamel rod decussation and that the DEJ plays a minor role.


Assuntos
Colagem Dentária/métodos , Esmalte Dentário/química , Dentina/química , Dente Molar/anatomia & histologia , Cimentos de Resina/química , Adolescente , Adulto , Materiais Biocompatíveis/química , Análise do Estresse Dentário , Análise de Elementos Finitos , Humanos , Teste de Materiais , Modelos Teóricos , Dente Molar/química , Estresse Mecânico , Propriedades de Superfície , Resistência à Tração , Fraturas dos Dentes , Adulto Jovem
20.
J Mech Behav Biomed Mater ; 77: 501-509, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29040961

RESUMO

OBJECTIVES: The aim of this study was to determine the effect of double-layer application of universal adhesives on the bond quality and compare to other adhesive systems. METHODS: Two universal adhesives used were in this study: Scotchbond Universal (SU), [3M ESPE] and Prime & Bond elect (PE), [Dentsply Caulk]. The conventional single-step self-etch adhesives G-ӕnial Bond (GB), [GC Corporation.] and BeautiBond (BB), [Shofu Inc.], and a two-step self-etch adhesive, Optibond XTR (OX), [Kerr Corporation], were used as comparison adhesives. Shear bond strengths (SBS) and shear fatigue strengths (SFS) to human enamel and dentin were measured in single application mode and double application mode. For each test condition, 15 specimens were prepared for SBS testing and 30 specimens for SFS testing. RESULTS: Enamel and dentin SBS of the universal adhesives in the double application mode were significantly higher than those of the single application mode. In addition, the universal adhesives in the double application mode had significantly higher dentin SFS values than those of the single application mode. The two-step self-etch adhesive OX tended to have lower bond strengths in the double application mode, regardless of the test method or adherent substrate. CONCLUSION: The double application mode is effective in enhancing SBS and SFS of universal adhesives, but not conventional two-step self-etch adhesives. SIGNIFICANCE: These results suggest that, although the double application mode may enhance the bonding quality of a universal adhesive, it may be counter-productive for two-step self-etch adhesives in clinical use.


Assuntos
Bis-Fenol A-Glicidil Metacrilato/química , Resinas Compostas/química , Cimentos Dentários/química , Dente Molar/química , Ácidos Polimetacrílicos/química , Cimentos de Resina/química , Análise de Variância , Fenômenos Biomecânicos , Colagem Dentária/métodos , Esmalte Dentário/química , Materiais Dentários/química , Falha de Restauração Dentária , Análise do Estresse Dentário , Dentina/química , Adesivos Dentinários/química , Humanos , Teste de Materiais , Microscopia Eletrônica de Varredura , Resistência ao Cisalhamento
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA