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1.
Nature ; 583(7814): 66-71, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32612224

RESUMO

Dental enamel is a principal component of teeth1, and has evolved to bear large chewing forces, resist mechanical fatigue and withstand wear over decades2. Functional impairment and loss of dental enamel, caused by developmental defects or tooth decay (caries), affect health and quality of life, with associated costs to society3. Although the past decade has seen progress in our understanding of enamel formation (amelogenesis) and the functional properties of mature enamel, attempts to repair lesions in this material or to synthesize it in vitro have had limited success4-6. This is partly due to the highly hierarchical structure of enamel and additional complexities arising from chemical gradients7-9. Here we show, using atomic-scale quantitative imaging and correlative spectroscopies, that the nanoscale crystallites of hydroxylapatite (Ca5(PO4)3(OH)), which are the fundamental building blocks of enamel, comprise two nanometric layers enriched in magnesium flanking a core rich in sodium, fluoride and carbonate ions; this sandwich core is surrounded by a shell with lower concentration of substitutional defects. A mechanical model based on density functional theory calculations and X-ray diffraction data predicts that residual stresses arise because of the chemical gradients, in agreement with preferential dissolution of the crystallite core in acidic media. Furthermore, stresses may affect the mechanical resilience of enamel. The two additional layers of hierarchy suggest a possible new model for biological control over crystal growth during amelogenesis, and hint at implications for the preservation of biomarkers during tooth development.


Assuntos
Amelogênese , Esmalte Dentário/química , Ácidos/química , Cálcio/química , Carbonatos/química , Cristalização , Teoria da Densidade Funcional , Esmalte Dentário/ultraestrutura , Durapatita/química , Fluoretos/química , Humanos , Magnésio/química , Microscopia Eletrônica de Transmissão e Varredura , Sódio/química , Tomografia , Difração de Raios X
2.
Arch Oral Biol ; 112: 104682, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32126356

RESUMO

OBJECTIVE: The aim of this study was to determine the heterogeneity in chemical composition of bovine enamel using atom probe tomography, and thereby evaluate the suitability of bovine enamel as a substitute for human enamel in in vitro dental research. DESIGN: Enamel samples from extracted bovine incisor teeth were first sectioned using a diamond saw and then milled into needle-like samples (<100 nm diameter) by focused ion beam (FIB) coupled with a scanning electron microscope (SEM). These samples were analyzed in the atom probe to acquire three-dimensional (3D) images and quantify the atomic chemistry and distribution in bovine enamel. RESULTS: For the first time, the atomic-level composition and clustering of major constituents and impurities within bovine enamel were determined and imaged. We discovered that the chemical composition of bovine enamel is spatially inhomogeneous at the atomic scale. The average bulk Ca/P ratio, ∼1.4, was in agreement with previously reported literature values from alternative conventional methods. When assessed locally at the atomic scale, the Ca/P ratio varied between 1.1 and 2.03. We also discovered that the Mg impurities were significantly segregated throughout the enamel, and such clustering influenced the variation of Ca/P ratios. The increase in Mg concentrations, near the Mg clusters, correlated with increased Ca and decreased P concentrations. CONCLUSION: The presented findings of variability in local composition should be taken into account when interpreting dental research results from bovine enamel.


Assuntos
Esmalte Dentário/ultraestrutura , Tomografia , Animais , Bovinos , Incisivo , Microscopia Eletrônica de Varredura
3.
BMC Oral Health ; 19(1): 247, 2019 11 14.
Artigo em Inglês | MEDLINE | ID: mdl-31727047

RESUMO

BACKGROUND: The aim of the present investigation was to evaluate enamel reduction efficiency, abrasive property decay, and enamel effects between oscillating mechanical and manual systems for interproximal enamel reduction (IPR). METHODS: Three oscillating strips and three manual strips were tested on twelve freshly extracted premolars blocked in an acrylic cylinder pot by means of a material testing machine. Each strip underwent one test of 8 cycles (30 s each). Both abrasive tracks and teeth surfaces were qualitative evaluated before and after IPR by means of SEM analysis. Efficiency and abrasive property decay of both IPR systems were investigated by the amount of enamel reduction within the eight-cycle testing. Independent t-test was used to evaluate differences in variables between the two systems. RESULTS: Mechanical IPR system showed higher efficiency in terms of enamel reduction (p < 0.005) when compared with manual IPR system (0.16 mm and 0.09 mm, respectively). Quantity of removed enamel decreased throughout the 8 cycles for both systems. Less presence of enamel debris and detachment of abrasive grains were observed on mechanical strips rather than manual strips. SEM analysis revealed more regular surface of teeth undergone mechanical IPR procedures. CONCLUSION: Oscillating diamond strips showed more controlled efficiency when compared with the manual IPR system leading to a more regular enamel surface.


Assuntos
Esmalte Dentário/efeitos dos fármacos , Diamante , Microabrasão do Esmalte/métodos , Dente Pré-Molar , Esmalte Dentário/patologia , Esmalte Dentário/ultraestrutura , Microabrasão do Esmalte/instrumentação , Humanos , Teste de Materiais , Microscopia Eletrônica de Varredura , Propriedades de Superfície
4.
Biomed Res Int ; 2019: 9101642, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31781651

RESUMO

Objective: This in vitro study is aimed at investigating the caries preventive effectiveness of 445 nm diode laser in combination with topical fluoridation. Materials and methods: A total of 30 caries-free bovine teeth were used in this study. Eighteen teeth were covered with nail varnish except four windows on the labial surface. The windows were assigned to no treatment/control (C), laser (L) (0.3 W, 60 s, and 90 J/cm2), fluoride (F), and fluoride followed by laser (FL) treatment groups. Artificial caries lesions were created, and the teeth were sectioned and investigated under polarized light microscopy for quantitative measurement of the resulted lesion depth. Ten teeth were used for surface temperature measurement and two teeth for scanning electron microscopy (SEM). Extra twelve human molars were used for the intrapulpal temperature measurement. The absorbance of fluoride at 445 nm was measured. Results: The means of lesion depth for the C, L, F, and FL groups were 123.48 (±21.93), 112.33 (±20.42), 99.58 (±30.68), and 89.03 (±30.38) µm, respectively. The pairwise differences of the L, F, and FL groups compared with the C group were significant (p < 0.05). The differences between groups were tested: FL versus L p=0.02, F versus L p=0.16, and FL versus F p=0.91, and the difference of the F versus FL was not significant (p=0.91). Temperature increment at the enamel surface and pulp roof were ∆T = 16.67 (±4.11) and 2.12 (±0.66)°C, respectively. The topical fluoride absorbance at 445 nm is five orders higher than that at 810 nm. SEM shows that after laser irradiation the enamel surface was intact and without thermal damage. Conclusions: The 445 nm laser irradiation may be useful for caries prevention, and its effectiveness is lower than those previously achieved using the argon ion laser.


Assuntos
Cárie Dentária/prevenção & controle , Fluoretos Tópicos/uso terapêutico , Lasers Semicondutores/uso terapêutico , Terapia com Luz de Baixa Intensidade , Animais , Bovinos , Cárie Dentária/tratamento farmacológico , Cárie Dentária/radioterapia , Suscetibilidade à Cárie Dentária , Esmalte Dentário/ultraestrutura , Polpa Dentária/ultraestrutura , Humanos , Microscopia Eletrônica de Varredura , Microscopia de Polarização , Dente Molar/ultraestrutura , Temperatura , Dente/ultraestrutura
5.
Nan Fang Yi Ke Da Xue Xue Bao ; 39(9): 1113-1117, 2019 Sep 30.
Artigo em Chinês | MEDLINE | ID: mdl-31640964

RESUMO

OBJECTIVE: To explore the histological structure of the deciduous teeth and the tooth germs of Tibetan miniature pigs for studies of dental tissue diseases and tooth regeneration. METHODS: The structure of the deciduous teeth of Tibetan miniature pigs was observed by X-ray. The ultrastructure of the enamel and dentin of deciduous teeth was characterized by scanning electron microscopy. The jaws and teeth were three-dimensionally reconstructed using Mimics software based on Micro-CT scanning of the deciduous teeth. Image J software was used to calculate the gray value and the mineralization density of the deciduous teeth. Hisotological structure of the tooth germ and the pulp tissue of Tibetan miniature pigs was observed using HE staining. RESULTS: The deciduous teeth of Tibetan miniature pigs were composed of enamel, dentin and medullary pulp tissue. The permanent tooth germ were formed during the deciduous dentition. The enamel and dentin ultrastructure of deciduous teeth were consistent with that of human deciduous teeth. The enamel and dentin mineralization densities were 2.47±0.09 g/cm3 and 1.72±0.07 g/cm3, respectively. The pathological structures of tooth germ and pulp tissue were similar to those of human teeth, and the pulp tissue of the deciduous teeth was in an undifferentiated state. CONCLUSIONS: The deciduous teeth of Tibetan miniature pig have similar anatomy, ultrastructure and histopathological structure to human teeth and can serve as a good animal model for studying human dental tissue diseases and the mechanisms of tooth regeneration.


Assuntos
Porco Miniatura , Dente Decíduo/anatomia & histologia , Animais , Esmalte Dentário/ultraestrutura , Polpa Dentária , Dentina/ultraestrutura , Suínos , Tibet , Germe de Dente
6.
Nat Commun ; 10(1): 4383, 2019 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-31558712

RESUMO

Enamel is the hardest and most resilient tissue in the human body. Enamel includes morphologically aligned, parallel, ∼50 nm wide, microns-long nanocrystals, bundled either into 5-µm-wide rods or their space-filling interrod. The orientation of enamel crystals, however, is poorly understood. Here we show that the crystalline c-axes are homogenously oriented in interrod crystals across most of the enamel layer thickness. Within each rod crystals are not co-oriented with one another or with the long axis of the rod, as previously assumed: the c-axes of adjacent nanocrystals are most frequently mis-oriented by 1°-30°, and this orientation within each rod gradually changes, with an overall angle spread that is never zero, but varies between 30°-90° within one rod. Molecular dynamics simulations demonstrate that the observed mis-orientations of adjacent crystals induce crack deflection. This toughening mechanism contributes to the unique resilience of enamel, which lasts a lifetime under extreme physical and chemical challenges.


Assuntos
Amelogênese , Esmalte Dentário/ultraestrutura , Dente Serotino/ultraestrutura , Cristalização , Esmalte Dentário/metabolismo , Humanos , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Dente Serotino/metabolismo , Simulação de Dinâmica Molecular , Adulto Jovem
7.
Microsc Res Tech ; 82(11): 1884-1890, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31400189

RESUMO

Determining surface topography of different tissues of the molar tooth with novel analytical methods has opened new horizons in dental surface measurements which characterize tooth surface quality in dentistry. Studying surface topological measurements and comparing surface morphology of hard tissue of the molar tooth are the ultimate goals of the present study. Ten molar teeth have been chosen for investigating their surface characteristics through image processing techniques. The power spectral density (PSD) and fast Fourier transform algorithms of every molar tooth containing enamel, dentin, and cementum have determined that the characterization of surface profiles is possible. As can be seen, PSD along with fractal dimensions leads to good results for teeth surface topography. Moreover, PSD angular plot assures appropriate description of surface.


Assuntos
Cemento Dentário/ultraestrutura , Esmalte Dentário/ultraestrutura , Dentina/ultraestrutura , Fractais , Dente Molar/ultraestrutura , Adulto , Cristalografia por Raios X , Análise de Fourier , Dureza/fisiologia , Humanos , Masculino , Microscopia de Força Atômica , Dente Molar/diagnóstico por imagem , Propriedades de Superfície
8.
Dokl Biol Sci ; 486(1): 79-82, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31317450

RESUMO

In small mammals, the degree of micro- and mesowear of molars depends on the feed hardness, abrasiveness, and some other characteristics. Analysis of micro- and mesorelief of the paleontological material is used for reconstruction of some animal diet parameters. Small mammals pass through a series of complex transformations on the way from the objects of biocenosis to paleontological objects. Bone remains underwent transformations during accumulation and fossilization. In particular, bone remains from ornithogenous deposits were exposed to the bird digestive system elements. We have experimentally studied changes in some parameters of the narrow-headed vole (Microtus gregalis) molars derived from the owl pellets. Comparison of the same samples before and after exposure to the digestive system of the polar owl (Nyctea scandiaca) and eagle owl (Bubo bubo) showed that the tooth enamel microrelief undergoes serious changes and therefore, provides no information on the intravital diet of voles. A different degree of preservation of the characteristics of the mesorelief was shown. Depending on this, an assessment of their applicability to paleoreconstructions was given.


Assuntos
Arvicolinae/anatomia & histologia , Esmalte Dentário/ultraestrutura , Dieta , Dente Molar/anatomia & histologia , Estrigiformes/fisiologia , Animais , Arvicolinae/fisiologia , Comportamento Alimentar
9.
Microsc Res Tech ; 82(10): 1668-1680, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31259458

RESUMO

The study aimed at finding an optimal combination of acid concentration and etching time when nitric acid is used as etchant for the study of the finer details of human dental enamel structure. Four hundred 2-3-mm-thick segments of facio-lingually sectioned human third molar crowns were assigned to 20 groups with 20 specimens in each group, each group differing with respect to acid concentration (0.1, 1, 2.5, and 5%) and etching time (15, 30, 45, 90, and 180 s). After etching and preparation, specimens were observed in the scanning electron microscope (SEM). Surface roughness/topography increased with increasing acid concentration and increasing etching time, but not in a linear fashion; generally, prisms tended to go from flat-surfaced to cone-shaped and prism sheaths from fissure-like to wedge-shaped. Intragroup variations and intergroup similarities were considerable. The two major enamel factors determining the etch effect are crystal orientation and prism sheath properties. Other factors, such as distribution of porosities and crystal quality, also contribute probably. Slight to moderate topography is best for observing the finer enamel structure, for example, etching with concentrations in the range 0.1-1% and with etching times in the range 15-90 s, the stronger the acid, the shorter the time. The depth effect of nitric acid is judged to be relatively small. Considerable variations in expression of prism cross-striations were observed. SEM observations of acid-etched enamel in carefully selected planes are a powerful method for the study of enamel structure, bearing in mind the artifactual aspects of the observed surface.


Assuntos
Ácidos/metabolismo , Esmalte Dentário/ultraestrutura , Corrosão Dentária/métodos , Humanos , Microscopia Eletrônica de Varredura , Dente Molar/ultraestrutura , Propriedades de Superfície , Fatores de Tempo
10.
Acta Odontol Latinoam ; 32(1): 29-35, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31206572

RESUMO

The aim of this study was to evaluate the deproteinization of primary enamel by analyzing etching pattern types, with and without the application of 5% NaOCl before acid etching with 37% H3PO4. Fifteen extracted human primary molars were randomly selected for the present in vitro study; 1mm x 1mm blocks were prepared and divided into two groups (n = 21). These groups were treated as follows: Group A- Acid Etching with 37% H3PO4 gel for 15 s; Group B- 5% NaOCl for 60 s + Acid Etching with 37% H3POfor 15 s. The specimens were prepared for scanning electron microscopy analysis. The images were evaluated for quality types I and II etching of the enamel surface using ImageJ software. Datasets were checked for normality by Kolgomorv-Smirnov test and the nonparametric unpaired Mann-Whitney test was applied. The mean surface area of type I and II etching pattern values was 1922.314 µm2for Group A and 3840.473 µm2Group B. We conclude that deproteinization with 5% NaOCl prior to acid etching can be used to increase the area of adhesion and the quality of the etching pattern.


Assuntos
Condicionamento Ácido do Dente/métodos , Colagem Dentária , Proteínas do Esmalte Dentário/efeitos dos fármacos , Esmalte Dentário/efeitos dos fármacos , Materiais Dentários/farmacologia , Ácidos Fosfóricos/farmacologia , Hipoclorito de Sódio/farmacologia , Dente Decíduo/efeitos dos fármacos , Colagem Dentária/métodos , Esmalte Dentário/ultraestrutura , Proteínas do Esmalte Dentário/ultraestrutura , Corrosão Dentária , Humanos , Microscopia Eletrônica de Varredura , Desnaturação Proteica , Cimentos de Resina , Propriedades de Superfície , Dente Decíduo/ultraestrutura
11.
Spectrochim Acta A Mol Biomol Spectrosc ; 222: 117271, 2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31226619

RESUMO

Structural changes in the enamel surface subjected to induced demineralization and assessment of the influence of prenatal administration of ß-hydroxy ß-methylbutyrate (HMB) on enamel resistance were investigated. The examination was conducted on five sets of teeth from one-day-old spiny mice (Acomys cahirinus), one from the control and four from the experimental groups. Surface structure, molecular arrangement and crystalline organization of offspring's enamel both before and after etching were studied. Obtained results revealed that the physical and molecular arrangements of enamel were altered after the prenatal supplementation, and significantly affected its final structure and resistance against acid action. The enamel of incisors from the offspring which mothers were supplemented with HMB in a high dose (0.2 g/kgbw) and in the late period of gestation (26th-39th day) showed the highest endurance against acid treatment demonstrating only vestigial changes in their surface structure after acid action. Comparing to the remaining experimental groups, it was characterized by a reduced roughness and fractal dimension, significantly lower degree of demineralization and simultaneous lack of notable differences in the Raman spectra before and after acid etching. The results suggest that an increased enamel resiliency was the effect of a relatively high degree of mineralization and higher organization of the surface.


Assuntos
Esmalte Dentário/efeitos dos fármacos , Valeratos/farmacologia , Ácidos/química , Animais , Animais Recém-Nascidos , Esmalte Dentário/embriologia , Esmalte Dentário/ultraestrutura , Suplementos Nutricionais , Feminino , Camundongos , Modelos Moleculares , Gravidez , Cuidado Pré-Natal , Propriedades de Superfície/efeitos dos fármacos , Valeratos/administração & dosagem
12.
Microsc Res Tech ; 82(9): 1489-1499, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31150562

RESUMO

The present study aims to evaluate the effect of brushing with fluoride dentifrice on teeth severely affected by erosion due to respiratory medicaments. Enamel (n = 50) and dentin (n = 50) bovine specimens were prepared and treated with artificial saliva (S-control), acebrofilin hydrochloride (AC), ambroxol hydrochloride (AM), bromhexine hydrochloride (BR), and salbutamol sulfate (SS) and subjected to cycles of demineralization (immersing in 3 mL, 1 min, three times a day at intervals of 1 hr, for 5 days) followed by remineralization (saliva, 37°C, 1 hr). Simulated brushing with fluoridated toothpaste was performed using 810 strokes in a reciprocal-action brushing simulator. Scanning electron microscopy, micro energy dispersive X-ray fluorescence (µ-EDXRF) spectroscopy and attenuated total reflection Fourier transform infrared (ATR FTIR) spectroscopy were then performed. µ-EDXRF images showed extensive erosion after treatment with all medicaments. SEM images showed enamel erosion in order SS > BR > AC = AM > S after brushing and fluoridation. FTIR results were in agreement. In case of dentin, µ-EDXRF measurements showed significant difference in mineral content (percent weight of calcium and phosphate) in SS + brushing + fluoridation treated enamel compared to control, while µ-EDXRF images showed erosive effects in the order SS > AM>BR > AC = S post brushing + fluoridation. SEM images showed erosion in the order SS > AM = BR > AC > S post brushing + fluoridation. Again, FTIR multivariate results were in agreement. Overall, our study shows that proper oral care is critical when taking certain medication. The study also demonstrates the possible use of FTIR for rapid clinical monitoring of tooth erosion in clinics.


Assuntos
Broncodilatadores/efeitos adversos , Microscopia Eletrônica de Varredura , Espectrometria por Raios X , Espectrofotometria Infravermelho , Desmineralização do Dente/induzido quimicamente , Dente/efeitos dos fármacos , Animais , Bovinos , Esmalte Dentário/química , Esmalte Dentário/efeitos dos fármacos , Esmalte Dentário/ultraestrutura , Dentina/química , Dentina/efeitos dos fármacos , Dentina/ultraestrutura , Dente/química , Dente/ultraestrutura
13.
Microsc Res Tech ; 82(9): 1419-1429, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31099955

RESUMO

The purpose of this study was to: (a) evaluate the role of enamel surface roughness on bond fatigue durability and (b) evaluate statistical differences in roughness values based on measurement technique, including the use of spatial filtering for optical profilometry (OP). OptiBond XTR (Kerr Corp), Prime & Bond elect (DENTSPLY Caulk), Scotchbond Universal (3 M Oral Care), and XTR pre-etched with Ultra-Etch phosphoric acid (35%) (Ultradent) self-etch adhesives were used to treat enamel. A flat ground enamel surface was included as a control. Atomic force microscopy (AFM) and OP were used to measure the surface topography of each enamel surface following the application of adhesives. AFM, OP, and filtered OP (FOP) roughness values, where FOP was designed to only include the lateral spatial resolution consistent with AFM roughness values, were collected. Spatial resolution filtering with OriginPro was used to compare line scans from the two imaging techniques and generate the FOP group. These micro- versus nanoscale lateral roughness values were correlated with shear bond and shear fatigue strengths of the adhesives bonded to enamel. Roughness values showed differences based on measurement technique and strong correlations with bond and fatigue strength. The filtered OP group demonstrated the importance of careful usage and reporting of atomic force microscopy and OP metrics in adhesive dentistry. Best practices for surface roughness analysis were also discussed.


Assuntos
Cimentos Dentários/análise , Esmalte Dentário/ultraestrutura , Análise de Falha de Equipamento/métodos , Microscopia de Força Atômica/métodos , Imagem Óptica/métodos , Propriedades de Superfície , Humanos , Dente Molar/ultraestrutura
14.
PLoS One ; 14(4): e0214948, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30951549

RESUMO

This work aimed to evaluate the roughness, microhardness, ultrastructure, chemical composition and crystalline structure in submitted teeth to a prolonged home bleaching regimen with 10% carbamide peroxide (10% PC) for different periods. The specimens were divided into the following groups: G1: negative control (application of water-soluble gel); G2: tooth whitening group (positive control), under application time recommended by the manufacturer (4h/14 days); G3: prolonged whitening 50%, under prolonged time recommended by the manufacturer in 50% (4h/21 days); G4: excessive whitening 100%, under exceeded manufacturer recommended time by 100% (4h/ 28 days). The results were evaluated descriptively and analytically. There were no changes in the roughness in any of the evaluated groups. However, the microhardness decreased in the G4 group. Scanning electron microscopy showed changes in the enamel surface of groups G2, G3 and G4. Dispersive X-ray spectroscopy identified changes in the concentration of chemical elements O, Mg, P, K in all groups. Thus, this study showed that prolonged home bleaching could cause changes in the ultrastructure, chemical composition and microhardness of the enamel.


Assuntos
Peróxido de Carbamida/farmacologia , Esmalte Dentário , Dureza/efeitos dos fármacos , Clareamento Dental , Animais , Bovinos , Esmalte Dentário/metabolismo , Esmalte Dentário/ultraestrutura , Microscopia Eletrônica de Varredura , Propriedades de Superfície/efeitos dos fármacos
15.
Mater Sci Eng C Mater Biol Appl ; 100: 354-362, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30948071

RESUMO

Natural bio-ceramics have attracted extensive interests due to its high strength and high toughness, which can hardly be achieved in artificial ceramics simultaneously. In this work, the microstructure and properties of the wild boar's tusk enamel were investigated. The enamel was found to exhibit a hierarchical structure ranging from the hydroxyapatite (HAP) fibers (single or poly-crystals, nano-scale), enamel rods (micro-scale), enamel types (meso-scale) to enamel patterns (macro-scale). It is worth mentioning that the high-density and high-order hierarchical nanotwins were observed in the HAP fibers. The mechanical properties of the wild boar's tusk enamel showed strong anisotropy and were higher along the longitudinal direction than along the transverse direction. The mechanical properties varied from the dentin-enamel junction (DEJ) to the outer surface. The elastic modulus increased with the distance from the DEJ and then kept invariant. The nano-hardness increased in inner enamel but decreased in outer enamel. There was a peak of nano-hardness in inner enamel area. The fracture toughness showed an opposite tendency. It exhibited high values in inner enamel, but fell in the outer enamel zone. The irregular, decussating texture of the enamel, as well as the nanotwins/hierarchical nanotwins was considered as the main reason for its excellent mechanical properties. These unique structures of the wild boar's tusk enamel are expected to cast light on the design of medical materials and provide some guidelines to improve their mechanical properties.


Assuntos
Esmalte Dentário/anatomia & histologia , Esmalte Dentário/fisiologia , Sus scrofa/anatomia & histologia , Animais , Fenômenos Biomecânicos , Esmalte Dentário/ultraestrutura , Módulo de Elasticidade , Dureza , Nanopartículas/química , Nanopartículas/ultraestrutura , Difração de Raios X
16.
Oral Health Prev Dent ; 17(2): 179-185, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30874251

RESUMO

PURPOSE: To evaluate the inhibitory effects of different toothpastes on demineralisation of incipient enamel lesions using a toothbrush simulator. MATERIALS AND METHODS: Fifty enamel specimens were prepared from extracted human molars. The specimens were randomly assigned to the following groups (n = 10/group): 1. no treatment (control); 2. toothpaste containing arginine (ProRelief, Colgate;); 3. fluoride toothpaste (Pronamel, Sensodyne GlaxoSmithKlein); 4. tooth mousse containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) (Recaldent, GC); 5. toothpaste (Restore, Dr. Collins) containing bioactive glass (NovaMin, GlaxoSmithKlein). All specimens were exposed to pH cycling. The remineralising agents were applied to the samples with a toothbrush simulator for 2 min twice a day for five days. The weight percentage of mineral changes for the elements calcium (Ca), phosphorus (P), sodium (Na) and silica (Si) were measured by SEM energy-dispersive x-ray spectroscopy (SEM-EDX). SEM revealed properties of treated enamel surfaces. The data were analysed using one-way ANOVA. RESULTS: Statistically significantly higher levels of Ca and P were found in all groups compared to the control (p < 0.05). CONCLUSIONS: The toothpastes' efficacy of inhibiting demineralisation depended on the active ingredients in the respective toothpaste. The demineralisation inhibition efficacy of the tested toothpastes depended on the active ingredients in the toothpaste.


Assuntos
Esmalte Dentário/ultraestrutura , Desmineralização do Dente/tratamento farmacológico , Remineralização Dentária , Cremes Dentais/uso terapêutico , Arginina/uso terapêutico , Cálcio , Cariostáticos/uso terapêutico , Caseínas/uso terapêutico , Esmalte Dentário/química , Fluoretos/uso terapêutico , Vidro , Humanos , Técnicas In Vitro , Microscopia Eletrônica de Varredura , Dente Molar , Fósforo , Dióxido de Silício , Espectrometria por Raios X , Escovação Dentária/métodos
17.
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
18.
Methods Mol Biol ; 1922: 293-308, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30838585

RESUMO

Scanning electron microscopy (SEM) is exceptionally well suited for the study of the structure of dental enamel, due to its ability to create high-resolution images of hard surfaces. Continuous attention on how to arrive at the observation stage with a clean and dry specimen is one main aspect of specimen preparation. Other main aspects are choice of whether the specimen should be embedded or not, choice of plane of section, and choice of acid-etching regime. Special attention is given to the preparation of small specimens and how to prepare and observe more than one plane or aspect in the same specimen.


Assuntos
Esmalte Dentário/ultraestrutura , Microscopia Eletrônica de Varredura/métodos , Animais , Desenho de Equipamento , Humanos , Microscopia Eletrônica de Varredura/instrumentação , Tamanho da Amostra , Manejo de Espécimes/instrumentação , Manejo de Espécimes/métodos
19.
Methods Mol Biol ; 1922: 309-324, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30838586

RESUMO

3D analysis of animal or human whole teeth and alveolar bone can be performed with high sensitivity in a nondestructive manner by microcomputed tomography. Here we describe the protocols to be followed for the most common applications in the developmental studies of dental and craniofacial tissues. Emphasis is placed on the basis of choosing settings for image acquisition, such as voxel resolution (Fig. 1), or beam energy (Fig. 2) and for processing, such as segmentation method (Fig. 3), parameters. The limitations to take into account for optimal efficiency and image quality are also explained.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Odontogênese , Dente/crescimento & desenvolvimento , Microtomografia por Raio-X/métodos , Animais , Esmalte Dentário/crescimento & desenvolvimento , Esmalte Dentário/ultraestrutura , Humanos , Mandíbula/crescimento & desenvolvimento , Mandíbula/ultraestrutura , Camundongos , Manejo de Espécimes/métodos , Dente/ultraestrutura
20.
J Appl Biomater Funct Mater ; 17(1): 2280800018816013, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30803291

RESUMO

INTRODUCTION:: The technique of sealing is a widely accepted procedure for prevention of caries. The aim of our in vitro study was to compare the effect of two different curing units (traditional LED source and innovative laser diode lamp) on the integrity of fissure sealant material and its interface with tooth enamel. MATERIALS AND METHODS:: Sixty healthy third molars were randomly assigned to two groups. In group A were teeth intended for polymerization by LED B lamp, and group B comprised teeth to be polymerized by an innovative laser diode. Both groups were treated with the traditional sealing technique, subjected to a metallization process, and analyzed by scanning electron microscope. RESULTS:: Micro-gaps between the sealant and the enamel were found in specimens in both A (43%) and B (40%) groups ( p=0.793), and sealant shrinkage was seen. Significant differences between the groups emerged in the percentage of perimetric micro-erosion sites (80% vs. 100%, p=0.010) and the presence of holes and micro-bubbles on the sealant surface (21% vs. 63%, p=0.001). CONCLUSIONS:: Although macroscopic clinical polymerization occurred with both instruments, the microscopic evaluation showed significant differences between the studied groups in terms of perimetric micro-erosion sites and micro-bubbles, which were higher in laser-cured samples.


Assuntos
Lasers , Luz , Selantes de Fossas e Fissuras/química , Esmalte Dentário/ultraestrutura , Polimerização/efeitos da radiação , Propriedades de Superfície
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