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1.
J Adhes Dent ; 23(5): 461-467, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34549929

RESUMO

PURPOSE: To evaluate the microtensile bond strength (µTBS) of a one-step self-etch adhesive (1-SEA) to dentin and its interfacial nanomechanical properties after 8 years of water storage. MATERIALS AND METHODS: Flat coronal dentin surfaces of extracted human third molars were bonded with a 1-SEA (Clearfil S3 Bond Plus, CS3+) and built up with a hybrid resin composite (Clearfil AP-X). After storage in water for 24 h or 8 years, non-trimmed stick-shaped specimens were fabricated from the central part of each bonded tooth and subjected to the µTBS test at a crosshead speed of 1.0 mm/min. Failure modes and the morphology of debonded interfaces were analyzed using a scanning electron microscope (SEM). In addition, the elastic modulus (E) and hardness (H) of the adhesive layer and the resin composite were determined by an instrumented nanoindentation test. The acquired µTBS, E, and H data were statistically analyzed using t-tests to examine the effect of storage time (α = 0.05). RESULTS: The 8-year µTBS was slightly lower than that after 24 h, but the difference was not significant (p = 0.123). The SEM observation of debonded surfaces after 8 years revealed extrusions and lacunas. E and H of the adhesive layer and the resin composite significantly decreased over the 8-year water storage (p < 0.001). CONCLUSIONS: Although 8 years of water storage did not decrease the µTBS of CS3+ significantly, the observed failure mode patterns and significantly decreased nanomechanical properties indicated resin degradation of the adhesive and the resin composite.


Assuntos
Colagem Dentária , Dentina , Resinas Compostas , Cimentos Dentários , Análise do Estresse Dentário , Adesivos Dentinários , Humanos , Teste de Materiais , Cimentos de Resina , Estresse Mecânico , Propriedades de Superfície , Resistência à Tração
2.
Rinsho Shinkeigaku ; 61(8): 537-542, 2021 Aug 30.
Artigo em Japonês | MEDLINE | ID: mdl-34275951

RESUMO

Tetanus is an infectious disease induced by wound invasion of Clostridium tetani, which is ubiquitous among soil. Many more cases are reported in Japan than in other developed countries. In this study, we report 11 cases of tetanus experienced at our hospital and discuss the preceding trauma and treatment course. The mean age at onset was 68 years old (35-86 years) and 7 cases required intensive care. Some preceded injuries were clearly contaminated, and others were small and minor. Even minor injuries developed serious tetanus. Trauma was not identified in 2 cases yet both used their family garden every day and had a high risk of exposure to C tetani, suggesting that micro-wounds may have been a gateway to entry. The average length of stay in the intensive care unit was 28 days (4-73 days) and average total hospitalization was 55 days (13-114 days). Only 4 out of 11 cases were diagnosed correctly by the initial physician and others, especially when the trauma was minor or absent, were misdiagnosed even when presenting with characteristic symptoms like lockjaw and posterior neck stiffness. Tetanus should be diagnosed based on medical history and physical examination due to lack of high specific testing. Therefore, a detailed history taking is required, including hobbies in addition to the appropriate neurological examination, thereby facilitating a quick diagnosis and commencement of treatment as soon as possible.

3.
J Prosthodont Res ; 2021 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-34108298

RESUMO

PURPOSE: This retrospective study evaluated the periodontal tissues of the abutment teeth of removable partial dentures (RPDs) with rigid retainers and major connectors in patients with and without type 2 diabetes mellitus (T2D). METHODS: A total of 313 patients who had been treated with RPDs, including rigid retainers and major connectors, were divided into two groups: T2D and non-T2D. The periodontal parameters and radiographic bone heights of the abutment teeth were evaluated at baseline and at a 5-year examination during supportive periodontal therapy (SPT). For patients with accessible standardized radiographs, bone density was analyzed based on the gray level (GL) using digital subtraction radiography (n = 83). RESULTS: Overall, 739 abutment teeth (86 in the T2D group) of 235 patients (25 in the T2D group) were analyzed, and 95.0% (94.2% in the T2D group, and 95.2% in the non-T2D group) were maintained. The mean probing pocket depth significantly increased in both groups ( p < 0.001). There were significant changes in the radiographic bone height (p = 0.038) and GL on the side of the denture base area (p = 0.048) in the T2D group compared to those in the non-T2D group. CONCLUSIONS: Regardless of T2D, RPDs with rigid retainers and major connectors could prevent the progression of periodontal disease and successfully maintain most of the abutment teeth during 5-years of SPT. However, T2D may be significantly associated with loss of bone height reduction and density on the side of the denture base area.

4.
J Mech Behav Biomed Mater ; 120: 104571, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34029943

RESUMO

The loss of bone quantity and quality in postmenopausal female patients can be a problem for dental treatment. A sufficient intake of nutrients such as calcium, magnesium, and vitamins D and K is likely correlated with the mechanical properties of bone. In particular, vitamin K2, also called menaquinone (MK), inhibits bone loss in postmenopausal women. Here we demonstrate the microstructural and mechanical properties of bone recovery in ovariectomized (OVX) rats during MK-7 administration. Bilateral ovariectomy and a sham operation were performed on 14-week-old female SPF Wistar rats. MK-4 and -7 were orally administered at 30 mg/kg daily for 12 weeks. The femur was used for the 3-point bending test and microstructural analysis of the cancellous bone by micro-CT, and the mandibular cortical bone for the evaluation of mechanical properties on a nanoscale. Micro-computed tomography revealed irregular trabecular architecture, hollow marrow cavities, and sparse trabecular bone in the femurs of the OVX group. Trabecular bone structure analysis showed that the MK-7 group had greater bone volume per tissue volume (BV/TV) and a higher trabecular number than the OVX group. The bulk-scale 3-point bending test did not allow the mechanical properties between OVX and OVX/MK7 groups to be discerned, yet at the smallest level, the elastic-plastic transition point of the nanoindentation stress-strain curve of the mandibular cortical bone was higher in the MK-7 group than in the OVX group. These findings suggest that MK-7 enables bone microstructural and mechanical recovery in the OVX model.


Assuntos
Densidade Óssea , Animais , Feminino , Humanos , Ovariectomia , Ratos , Ratos Wistar , Vitamina K 2/análogos & derivados , Vitamina K 2/farmacologia , Microtomografia por Raio-X
5.
Front Immunol ; 12: 624614, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33936039

RESUMO

Primary Sjogren's syndrome (pSS) is a chronic progressive autoimmune disease with clinical phenotypic "Sicca symptoms". In some cases, the diagnosis of pSS is delayed by 6-7 years due to the inefficient differential diagnosis of pSS and non-SS "Sicca". This study aimed to investigate the difference between these two diseases, and in particular, their immunopathogenesis. Based on their gene expression profiles, we systematically defined for the first time the predicted disease-specific immune infiltration pattern of patients with pSS differentiated from normal donors and patients with non-SS "Sicca". We found that it was characterized by the aberrant abundance and interaction of tissue-infiltrated immune cells, such as a notable shift in the subpopulation of six immune cells and the perturbed abundance of nine subpopulations, such as CD4+ memory, CD8+ T-cells and gamma delta T-cells. In addition, we identified essential genes, particularly long non-coding RNAs (lncRNAs), as the potential mechanisms linked to this predicted pattern reprogramming. Fourteen lncRNAs were identified as the potential regulators associated with the pSS-specific immune infiltration pattern in a synergistic manner, among which the CTA-250D10.23 lncRNA was highly relevant to chemokine signaling pathways. In conclusion, aberrant predicted disease-specific immune infiltration patterns and relevant genes revealed the immunopathogenesis of pSS and provided some clues for the immunotherapy by targeting specific immune cells and genes.


Assuntos
Aparelho Lacrimal/imunologia , RNA Longo não Codificante/genética , Glândulas Salivares/imunologia , Síndrome de Sjogren/genética , Subpopulações de Linfócitos T/imunologia , Transcriptoma , Estudos de Casos e Controles , Quimiocinas/genética , Quimiocinas/metabolismo , Bases de Dados Genéticas , Perfilação da Expressão Gênica , Redes Reguladoras de Genes , Humanos , Aparelho Lacrimal/metabolismo , Fenótipo , RNA Longo não Codificante/imunologia , RNA Longo não Codificante/metabolismo , Glândulas Salivares/metabolismo , Síndrome de Sjogren/imunologia , Síndrome de Sjogren/metabolismo , Subpopulações de Linfócitos T/metabolismo
6.
Biochem Biophys Res Commun ; 554: 173-178, 2021 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-33798944

RESUMO

Neural crest-derived cells (NCDCs), a class of adult stem cells not restricted to embryonic tissues, are attractive tissue regenerative therapy candidates because of their ease of isolation, self-renewing properties, and multipotency. Although adult NCDCs can undergo osteogenic differentiation in vitro, whether they induce bone formation in vivo remains unclear. Previously, our group reported findings showing high amounts of NCDCs scattered throughout nasal concha tissues of adult mice. In the present study, NCDCs in nasal conchae labeled with enhanced green fluorescent protein (EGFP) were collected from adult P0-Cre/CAG-CAT-EGFP double transgenic mice, then cultured in serum-free medium to increase the number. Subsequently, NCDCs were harvested and suspended in type I atelocollagen gel, then an atelocollagen sponge was used as a scaffold for the cell suspension. Atelocollagen scaffolds with NCDCs were placed on bone defects created in a mouse calvarial bone defect model. Over the ensuing 12 weeks, micro-CT and histological analysis findings showed that mice with scaffolds containing NCDCs had slightly greater bone formation as compared to those with a scaffold alone. Furthermore, Raman spectroscopy revealed spectral properties of bone in mice that received scaffolds with NCDCs similar to those of native calvarial bone. Bone regeneration is important not only for gaining bone mass but also chemical properties. These results are the first to show the validity of biomolecule-free adult nasal concha-derived NCDCs for bone regeneration, including the chemical properties of regenerated bone tissue.


Assuntos
Células-Tronco Adultas/citologia , Regeneração Óssea/fisiologia , Crista Neural/citologia , Transplante de Células-Tronco/métodos , Conchas Nasais/citologia , Células-Tronco Adultas/metabolismo , Animais , Diferenciação Celular , Células Cultivadas , Modelos Animais de Doenças , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Camundongos , Camundongos Endogâmicos ICR , Camundongos Transgênicos , Crista Neural/metabolismo , Conchas Nasais/metabolismo
7.
J Mech Behav Biomed Mater ; 117: 104389, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33647730

RESUMO

The presence of 10-methacryloyloxydecyl dihydrogen phosphate (MDP) at the adhesive-dentin interface enables ionic binding to calcium salts, which results in rigid nano-layering within the submicron scale resin-dentin interdiffusion zone. MDP has been used with additional co-monomers, such as hydroxyethyl methacrylate (HEMA) and/or 4-methacryloyloxyethyl-trimellitic acid (4-MET), mainly to enhance the chemical bonding properties. However, the use of co-monomers may compromise the rigidity of the adhesive-dentin interface. In this study, we use high-resolution mechanical mapping across the interface to discern the in situ mechanical properties of each target region at the nanoscale. Visualization by modulus mapping demonstrated that HEMA increases the diffusion properties of MDP into dentin structures. However, the rigidity of the adhesive-dentin interface indicated by the storage modulus was markedly lower in MDP containing HEMA than in MDP containing 4-MET. Dynamic indentation testing revealed that the bonding layer was more deformable in the presence of HEMA. Moreover, the presence of MDP in the bonding layer might also increase the deformability because the polymerization linearity allows a large degree of viscoelasticity. These factors also diminish the rigidity of the adhesive-dentin interface. Within the limitations of this study, our findings demonstrated that 4-MET is a better co-monomer than HEMA in MDP-based dental adhesives. Modulus mapping and nanoindentation are introduced as new tests for the adhesive-dentin interface to address queries about the effectiveness of dental adhesives.


Assuntos
Adesivos , Colagem Dentária , Dentina , Adesivos Dentinários , Substâncias Macromoleculares , Teste de Materiais , Metacrilatos , Cimentos de Resina
8.
J Mech Behav Biomed Mater ; 98: 20-25, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31176091

RESUMO

Initial intimate apposition between implant fixtures and host bone at the surgical site is a critical factor for osseointegration of dental implants. The advanced glycation end products accumulated in the jaw bone could lead to potential failure of a dental implant during the initial integration stage, because of the inferior bone mechanical property associated with the abnormal collagen cross-linking at the material level. Here, we demonstrate the lowered creep deformation resistance and reduced dimensional recovery of jaw bone in line with high levels of pentosidine accumulation in the bone matrix which likely correlate with the pentosidine level in blood plasma. Peripheral blood samples and cortical bone samples at the surgical site were obtained from patients scheduled for dental implants in the mandible. The pentosidine levels in blood plasma were assessed. Subsequently, the relative pentosidine levels and the mechanical properties of the jaw bone were quantified by Raman microspectroscopy and nanoindentation, respectively. The nanoindentation tests revealed less creep deformation resistance and reduced time-dependent dimensional recovery of bone samples with the increase in the relative pentosidine level in the bone matrix. Higher tan δ values at the various frequencies during the dynamic indentation tests also suggested that viscoelasticity is associated with the relative intensity of pentosidine in the jaw bone matrix. We found a positive correlation between the pentosidine levels in blood plasma and the bone matrix, which in turn reduced the mechanical property of the jaw bone at the material level. Increased creep and reduced dimensional recovery of the jaw bone may diminish the mechanical interlocking of dental implants during the initial integration stage. Given the likely correlation between the plasma pentosidine level and the mechanical properties of bone, measurement of the plasma pentosidine level could serve as a new index to assess jaw bone matrix quality in advance of implant surgery.


Assuntos
Arginina/análogos & derivados , Arcada Osseodentária/metabolismo , Lisina/análogos & derivados , Teste de Materiais , Fenômenos Mecânicos , Nanotecnologia , Arginina/metabolismo , Fenômenos Biomecânicos , Humanos , Arcada Osseodentária/fisiologia , Lisina/metabolismo
9.
Sci Rep ; 9(1): 4682, 2019 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-30886223

RESUMO

The aim of this study was to investigate the fracture behaviour of fissural dental enamel under simulated occlusal load in relation to various interacting factors including fissure morphology, cuspal angle and the underlying material properties of enamel. Extended finite element method (XFEM) was adopted here to analyse the fracture load and crack length in tooth models with different cusp angles (ranging from 50° to 70° in 2.5° intervals), fissural morphologies (namely U shape, V shape, IK shape, I shape and Inverted-Y shape) and enamel material properties (constant versus graded). The analysis results showed that fissures with larger curved morphology, such as U shape and IK shape, exhibit higher resistance to fracture under simulated occlusal load irrespective of cusp angle and enamel properties. Increased cusp angle (i.e. lower cusp steepness), also significantly enhanced the fracture resistance of fissural enamel, particularly for the IK and Inverted-Y shape fissures. Overall, the outcomes of this study explain how the interplay of compositional and structural features of enamel in the fissural area contribute to the resistance of the human tooth against masticatory forces. These findings may provide significant indicators for clinicians and technicians in designing/fabricating extra-coronal dental restorations and correcting the cuspal inclinations and contacts during clinical occlusal adjustment.


Assuntos
Simulação por Computador , Esmalte Dentário/fisiologia , Fissuras Dentárias/patologia , Fixação de Fratura/métodos , Dente Molar/fisiologia , Força de Mordida , Resinas Compostas/química , Restauração Dentária Permanente , Análise de Elementos Finitos , Humanos , Estresse Mecânico , Propriedades de Superfície
10.
J Mech Behav Biomed Mater ; 92: 71-78, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30660030

RESUMO

Dental adhesive provides effective retention of filling materials via adhesive-dentin hybridization. The use of co-monomers, such as 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP), is thought to be crucial for hybridization owing to their ionic-binding to calcium and co-polymerization in the polymerizable adhesives. Optimal hybridization partly depends on the mechanical properties of polymerized adhesives, which are likely to be proportional to the degree of conversion ratio. This study assessed the correlation between polymerization quality and mechanical properties at the adhesive-dentin interfaces in the presence or absence of 10-MDP. In situ Raman microspectroscopy and nanoindentation tests were used concurrently to quantify the degree of conversion ratio and dynamic mechanical properties across the adhesive-dentin interfaces. Despite the excellent diffusion and apparent higher degree of co-polymerization, 10-MDP reduced the elastic modulus of the interface. The higher viscoelastic properties of the adhesive are suggestive of poor polymerization, namely polymerization linearity related to the long carboxyl chain of 10-MDP. Such reduced mechanical integrity of hybridization could also be associated with the inhibition of nano-layering between 10-MDP and mineralized tissue in the presence of hydroxyethyl methacrylate (HEMA). This potential drawback of HEMA necessitates further qualitative/quantitative characterization of adhesive-dentin hybridization using a HEMA-free/low concentration experimental 10-MDP monomer, which theoretically possesses superior chemical bonding potential to the current HEMA-rich protocol.


Assuntos
Adesivos/química , Dentina/química , Fosfatos/química , Compostos de Sulfidrila/química , Metacrilatos , Nanotecnologia , Estresse Mecânico
11.
Dent Mater ; 35(1): 87-97, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30502962

RESUMO

OBJECTIVE: Tooth enamel has unsurpassed hardness and stiffness among mammalian tissue structures. Such stiff materials are usually brittle, yet mature enamel can survive for a lifetime. Understanding the nanoscale origin of enamel durability is important for developing advanced load-bearing biomaterials. Here, nanoscale exceptional contact elasticity of the human tooth enamel, based on nanoindentation tests, is reported. METHODS: Spherical indenter tips with radii of 243 and 1041nm were used to determine stress-strain curves of enamel. Force-displacement curves were recorded using quasi-static loading strain rates of 0.031, 0.041, and 0.061s-1. The storage moduli from a superimposed signal amplitude (dynamic strain at 220Hz) embedded during primary quasi-static loading and from quasi-static elastic theory were simultaneously measured. Modulus mapping was considered to be an extremely low quasi-static loading strain rate indentation test. RESULTS: The elastic limits were 7-9GPa and 5-6GPa for the small and large indenters, respectively. The elastic-plastic transition point and elastic modulus value increased with substantially increased quasi-static loading strain rate. The results suggested that the increase of the elastic limit during high-loading strain was associated with exceptional contact elasticity at the nanoscale of the enamel structure and the consequent extension of the contact area (i.e., a temporary pile-up response, dependent on the enamel nanocrystals and protein glue). SIGNIFICANCE: Structural modification at this scale effectively prevents the initiation of cracking from localized strain, thus reinforcing the bulk structure. These results may provide valuable insight for conceptualizing bio-inspired nanocomposites.


Assuntos
Esmalte Dentário , Animais , Módulo de Elasticidade , Elasticidade , Dureza , Humanos , Suporte de Carga
12.
J Mech Behav Biomed Mater ; 90: 248-255, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30388508

RESUMO

An increase in non-enzymatic collagen matrix cross-links, such as advanced glycation end-products (AGEs), is known to be a major complication in human mineralized tissues, often causing abnormal fractures. However, degradation of mechanical properties in relation to AGEs has not been fully elucidated at the material level. Here, we report nanoscale time-dependent deformation and dimensional recovery of human tooth dentin that has undergone glycation induced by x-ray irradiation. The reduction in enzymatic collagen cross-linking and the increased level of AGEs with concomitant growth of disordered collagen matrix diminished creep deformation recovery in the lower mineralized target region. However, the elevated AGEs level alone did not cause a reduction in time-dependent deformation and its recovery in the higher mineralized target region. In addition to the elevated AGEs level, the degradation of the mechanical properties of mineralized tissues should be assessed with care in respect to multiple parameters in the collagen matrix at the molecular level.


Assuntos
Dentina/metabolismo , Dentina/efeitos da radiação , Fenômenos Mecânicos/efeitos da radiação , Nanotecnologia , Adolescente , Adulto , Fenômenos Biomecânicos/efeitos da radiação , Colágeno/metabolismo , Glicosilação/efeitos da radiação , Humanos , Cinética , Teste de Materiais , Adulto Jovem
13.
Clin Calcium ; 27(8): 1139-1145, 2017.
Artigo em Japonês | MEDLINE | ID: mdl-28743850

RESUMO

Bone is an inhomogeneous, anisotropic natural biomaterial with complex, multiscale structural variations. Thus, experiments on the bulk scale using a universal testing machine are not applicable for localized precision mechanical testing of bone. Nanoscale mechanical testing technologies such as nanoindentation enables to assess the intrinsic toughening mechanism of bone, which is a function of the highly-organized matrix proteins within the mineralized nanostructure. Understanding the basic nanomechanical properties of calcified tissues will help us to appreciate general concepts associated with the excellent design of advanced engineering materials and engineered tissues.


Assuntos
Osso e Ossos/citologia , Fenômenos Biomecânicos , Densidade Óssea , Osso e Ossos/fisiologia , Tamanho Celular , Humanos , Nanoestruturas
14.
Nanomedicine ; 13(8): 2545-2553, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28754466

RESUMO

Although empirical findings have indicated increase in bone fracture risk in type 2 diabetes patients, that has yet to be proven by results obtained at the material level. Here, we report evidence showing nanoscale time-dependent deformation/recovery of in vitro calcified nodules mimicking bone turnover in type 2 diabetes in respect to methylglyoxal (MG)-induced glycation. Nanoindentation test results revealed that calcified nodules cultured with MG did not show adequate dimensional recovery, despite a large creep rate during constant load indentation testing. This lesser recovery is likely based on the linear matrix polymerization network formed by advanced glycation end products (AGEs) as a secondary product of MG. Since elevated serum MG and abnormal bone turnover related to the amount of AGEs are observed in cases of type 2 diabetes, this time-dependent behavior may be one of the factors of the bone fracture mechanism at the material level in affected patients.


Assuntos
Calcinose/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Produtos Finais de Glicação Avançada/metabolismo , Osteoblastos/metabolismo , Aldeído Pirúvico/metabolismo , Osso e Ossos/metabolismo , Osso e Ossos/patologia , Calcinose/patologia , Linhagem Celular , Proliferação de Células , Diabetes Mellitus Tipo 2/patologia , Humanos , Osteoblastos/citologia , Osteoblastos/patologia
15.
J Mech Behav Biomed Mater ; 65: 102-116, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27569758

RESUMO

This paper studied the surface quality (damage, morphology, and phase transformation) of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) in CAD/CAM milling, and subsequent polishing, sintering and sandblasting processes applied in dental restorations. X-ray diffraction and scanning electron microscopy (SEM) were used to scan all processed surfaces to determine phase transformations and analyse surface damage morphology, respectively. The average surface roughness (Ra) and maximum roughness (Rz) for all processed surfaces were measured using desk-top SEM-assisted morphology analytical software. X-ray diffraction patterns prove the sintering-induced monoclinic-tetragonal phase transformation while the sandblasting-induced phase transformation was not detected. The CAD/CAM milling of pre-sintered Y-TZP produced very rough surfaces with extensive fractures and cracks. Simply polishing or sintering of milled pre-sintered surfaces did not significantly improve their surface roughness (ANOVA, p>0.05). Neither sintering-polishing of the milled surfaces could effectively improve the surface roughness (ANOVA, p>0.05). The best surface morphology was produced in the milling-polishing-sintering process, achieving Ra=0.21±0.03µm and Rz=1.73±0.04µm, which meets the threshold for bacterial retention. Sandblasting of intaglios with smaller abrasives was recommended as larger abrasive produced visible surface defects. This study provides technical insights into process selection for Y-TZP to achieve the improved restorative quality.


Assuntos
Prótese Dentária , Teste de Materiais , Ítrio/análise , Zircônio/análise , Propriedades de Superfície
16.
J Mater Sci Mater Med ; 27(5): 86, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26970768

RESUMO

The choice of implant surface has a significant influence on osseointegration. Modification of TiZr surface by anodization is reported to have the potential to modulate the osteoblast cell behaviour favouring more rapid bone formation. The aim of this study is to investigate the effect of anodizing the surface of TiZr discs with respect to osseointegration after four weeks implantation in sheep femurs. Titanium (Ti) and TiZr discs were anodized in an electrolyte containing DL-α-glycerophosphate and calcium acetate at 300 V. The surface characteristics were analyzed by scanning electron microscopy, electron dispersive spectroscopy, atomic force microscopy and goniometry. Forty implant discs with thickness of 1.5 and 10 mm diameter (10 of each-titanium, titanium-zirconium, anodized titanium and anodized titanium-zirconium) were placed in the femoral condyles of 10 sheep. Histomorphometric and histologic analysis were performed 4 weeks after implantation. The anodized implants displayed hydrophilic, porous, nano-to-micrometer scale roughened surfaces. Energy dispersive spectroscopy analysis revealed calcium and phosphorous incorporation into the surface of both titanium and titanium-zirconium after anodization. Histologically there was new bone apposition on all implanted discs, slightly more pronounced on anodised discs. The percentage bone-to-implant contact measurements of anodized implants were higher than machined/unmodified implants but there was no significant difference between the two groups with anodized surfaces (P > 0.05, n = 10). The present histomorphometric and histological findings confirm that surface modification of titanium-zirconium by anodization is similar to anodised titanium enhances early osseointegration compared to machined implant surfaces.


Assuntos
Titânio/química , Zircônio/química , Animais , Materiais Biocompatíveis/química , Desenvolvimento Ósseo , Feminino , Teste de Materiais , Osseointegração/fisiologia , Próteses e Implantes , Ovinos , Propriedades de Superfície
17.
J Biomed Mater Res B Appl Biomater ; 104(1): 88-95, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25631358

RESUMO

In our previous study, glass-fiber-reinforced plastics (GFRPs) made from polycarbonate and glass fiber for esthetic orthodontic wires were prepared by using pultrusion. The purpose of the present study was to investigate the surface topography, hardness, and frictional properties of GFRPs. To investigate how fiber diameter affects surface properties, GFRP round wires with a diameter of 0.45 mm (0.018 in.) were prepared incorporating either 13 µm (GFRP-13) or 7 µm (GFRP-7) glass fibers. As controls, stainless steel (SS), cobalt-chromium-nickel alloy, ß-titanium (ß-Ti) alloy, and nickel-titanium (Ni-Ti) alloy were also evaluated. Under scanning electron microscopy and scanning probe microscopy, the ß-Ti samples exhibited greater surface roughness than the other metallic wires and the GFRP wires. The dynamic hardness and elastic modulus of GFRP wires obtained by the dynamic micro-indentation method were much lower than those of metallic wires (p < 0.05). Frictional forces against the polymeric composite brackets of GFRP-13 and GFRP-7 were 3.45 ± 0.49 and 3.60 ± 0.38 N, respectively; frictional forces against the ceramic brackets of GFRP-13 and GFRP-7 were 3.39 ± 0.58 and 3.87 ± 0.48 N, respectively. For both bracket types, frictional forces of GFRP wires and Ni-Ti wire were nearly half as low as those of SS, Co-Cr, and ß-Ti wires. In conclusion, there was no significant difference in surface properties between GFRP-13 and GFRP-7; presumably because both share the same polycarbonate matrix. We expect that GFRP wires will deliver superior sliding mechanics with low frictional resistance between the wire and bracket during orthodontic treatment.


Assuntos
Fricção , Vidro/química , Dureza , Fios Ortodônticos , Humanos
18.
J Mater Sci Mater Med ; 26(8): 221, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26260697

RESUMO

Titanium (Ti) and its alloys have been popularly used as implant biomaterial for decades. Recently, titanium-zirconium (TiZr) alloy has been developed as an alternative implant material with improved strength in load bearing areas. Surface modification is one of the key factors to alter the surface properties to hasten osseointegration. Spark anodic oxidation (anodization) is one such method that is reported to enhance the bone formation around implants. This study aims to anodize TiZr and study its surface characteristics and cytocompatibility by cell culture experiments using osteoblast-like cells. Titanium (Ti) and TiZr discs were anodized in an electrolyte containing DL-α-glycerophosphate and calcium acetate (CA) at 300 V. The surface characteristics were analyzed by scanning electron microscopy, electron dispersive spectroscopy, X-ray diffraction (XRD), atomic force microscopy and goniometry. Using osteoblast-like cells viability, proliferation, differentiation and mineralization was assessed. The anodized surfaces demonstrated increased oxygen, entrapped calcium and phosphorous from the electrolyte used. XRD analysis confirmed the presence of anatase in the oxide layer. Average roughness increased and there was a significant decrease in contact angle (P < 0.01) following anodization. The anodized TiZr (aTiZr) surfaces were more nano-porous compared to anodized Ti (aTi). No significant difference was found in the viability of cells, but after 24 h the total number of cells was significantly higher (P < 0.01). Proliferation, alkaline phosphatase activity and calcium deposits were significantly higher on anodized surfaces compared to machined surfaces (P < 0.05, ANOVA). Anodization of TiZr resulted in a more nanoporous and hydrophilic surface than aTi, and osteoblast biocompatibility appeared comparable to aTi.


Assuntos
Ligas/química , Materiais Biocompatíveis/química , Titânio/química , Zircônio/química , Diferenciação Celular , Linhagem Celular , Proliferação de Células , Sobrevivência Celular , Humanos , Teste de Materiais , Microscopia de Força Atômica , Microscopia Eletrônica de Varredura , Osseointegração , Osteoblastos/citologia , Próteses e Implantes , Propriedades de Superfície
19.
J Prosthodont Res ; 59(2): 84-95, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25797023

RESUMO

PURPOSE: The purpose of this article is to review the mechanical requirements of the tissue-implant interface and analyze related theories. STUDY SELECTION: The osseointegration capacity of titanium implants has been investigated over the past 50 years. We considered the ultimate goal of osseointegration to which form a desirable interfacial layer and a bone matrix with adequate biomechanical properties. RESULTS: Occasionally, the interface comprises porous titanium and bone ingrowth that enables a functionally graded Young's modulus, thereby allowing reduction of stress shielding. However, the optimal biomechanical connection at the interface has not yet been fully clarified. There have been publications supporting several universal mechanical testing technologies in terms of bone-titanium bonding ability, although the separation of newly formed bone quality is unlikely. CONCLUSIONS: The understanding of complex mechanical bone behavior and size-dependent properties ranging from a nano- to a macroscopic level are essential in the biomechanical optimization of implants. The requirements of regenerated tissue at the interface include high strength, fracture toughness related to ductility, and time-dependent energy dissipation and/or elastic-plastic stress distribution. Moreover, a strong relationship between strain signals and peri-implant tissue turnover could be expected, so that ideal implant biomechanics may enable longevity via adaptive bone remodeling.


Assuntos
Regeneração Óssea/fisiologia , Osso e Ossos/fisiologia , Interface Osso-Implante/fisiologia , Implantação Dentária Endo-Óssea/métodos , Implantes Dentários , Osseointegração/fisiologia , Titânio , Fenômenos Biomecânicos , Remodelação Óssea/fisiologia , Módulo de Elasticidade , Análise de Elementos Finitos , Humanos
20.
Biomaterials ; 47: 62-71, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25682161

RESUMO

The nanoscale structure-function relationship is a key determinant of bone toughness or micro-fragility. The loss of bone toughness during the aging process has been accepted based on empirical evidence, but this concept has not yet been fully supported by evidence at the material level. Here, we demonstrate a reduction in bone toughening mechanism in mimetic aged cortical bone obtained from α-klotho deficient (α-klotho(-/-)) mice and assessed by in situ dynamic mechanical analysis. The strain-rate nanoindentation tests showed enhanced stiffening of the wild-type calvarial bone and a large dimensional recovery during rapid loading following the constant displacement test. Such strain-dependent stiffening was likely associated with nanoscale dilatational bands and subsequent strain-energy transfer to the superior wild-type cross-linked collagen matrix network. The absence of dilatational bands formed by hydroxyapatite crystals and non-collagenous proteins in the α-klotho(-/-) bone samples likely diminished the intrinsic bone toughening mechanisms almost independent of viscoelastic behaviors. Such nanoscale structural alternations that occur during aging processes lead to crack propagation and result in overall bone fractures under large external stresses. In addition, dynamic mechanical analysis using instrumented nanoindentation was useful for the evaluation of bone mechanical properties in this pathological model of a genetic knockout mouse.


Assuntos
Materiais Biocompatíveis/química , Osso e Ossos/patologia , Glucuronidase/genética , Glucuronidase/fisiologia , Animais , Fenômenos Biomecânicos , Colágeno/química , Cristalização , Durapatita/química , Elasticidade , Fraturas Ósseas/patologia , Fraturas Ósseas/prevenção & controle , Masculino , Camundongos , Camundongos Knockout , Análise Espectral Raman , Estresse Mecânico
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