Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 133
Filtrar
1.
Front Bioeng Biotechnol ; 9: 617724, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33585434

RESUMO

Failure of corneal endothelium cell monolayer is the main cause leading to corneal transplantation. Autologous cell-based therapies are required to reconstruct in vitro the cell monolayer. Several strategies have been proposed using embryonic stem cells and induced pluripotent stem cells, although their use has ethical issues as well as limited clinical applications. For this purpose, we propose the use of dental pulp stem cells isolated from the third molars to form the corneal endothelium cell monolayer. We hypothesize that using dental pulp stem cells that share an embryological origin with corneal endothelial cells, as they both arise from the neural crest, may allow a direct differentiation process avoiding the use of reprogramming techniques, such as induced pluripotent stem cells. In this work, we report a two-step differentiation protocol, where dental pulp stem cells are derived into neural crest stem-like cells and, then, into corneal endothelial-like cells. Initially, for the first-step we used an adhesion culture and compared two initial cell sources: a direct formation from dental pulp stem cells with the differentiation from induced pluripotent stem cells. Results showed significantly higher levels of early stage marker AP2 for the dental pulp stem cells compared to induced pluripotent stem cells. In order to provide a better environment for neural crest stem cells generation, we performed a suspension method, which induced the formation of neurospheres. Results showed that neurosphere formation obtained the peak of neural crest stem cell markers expression after 4 days, showing overexpression of AP2, Nestin, and p75 markers, confirming the formation of neural crest stem-like cells. Furthermore, pluripotent markers Oct4, Nanog, and Sox2 were as well-upregulated in suspension culture. Neurospheres were then directly cultured in corneal endothelial conditioned medium for the second differentiation into corneal endothelial-like cells. Results showed the conversion of dental pulp stem cells into polygonal-like cells expressing higher levels of ZO-1, ATP1A1, COL4A2, and COL8A2 markers, providing a proof of the conversion into corneal endothelial-like cells. Therefore, our findings demonstrate that patient-derived dental pulp stem cells may represent an autologous cell source for corneal endothelial therapies that avoids actual transplantation limitations as well as reprogramming techniques.

2.
Materials (Basel) ; 13(6)2020 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-32245138

RESUMO

The use of narrow titanium dental implants (NDI) for small ridges, reduced interdental space, or missing lateral incisors can be a viable option when compared to the conventional wider dental implants. Furthermore, in many cases, standard diameter implant placement may not be possible without grafting procedures, which increases the healing time, cost, and morbidity. The aim of this study was to analyze the mechanical viability of the current narrow implants and how narrow implants can be improved. Different commercially available implants (n = 150) were tested to determine maximum strength, strain to fracture, microhardness, residual stress, and fatigue obtaining the stress-number of cycles to fracture (SN) curve. Fractography was studied by scanning electron microscopy. The results showed that when the titanium was hardened by the addition of 15% of Zr or 12% cold worked, the fatigue limit was higher than the commercially pure grade 4 Ti without hardening treatment. Grade 4 titanium without hardening treatment in narrow dental implants can present fractures by fatigue. These narrow implants are subjected to high mechanical stresses and the mechanical properties of titanium do not meet the minimal requirements, which lead to frequent fractures. New hardening treatments allow for the mechanical limitations of conventional narrow implants to be overcome in dynamic conditions. These hardening treatments allow for the design of narrow dental implants with enhanced fatigue life and long-term behavior.

3.
J Healthc Qual Res ; 35(2): 73-78, 2020.
Artigo em Espanhol | MEDLINE | ID: mdl-32241730

RESUMO

The development of a questionnaire that measures user satisfaction in the area of Rehabilitation is essential in order to measure the success achieved and to be able to introduce actions to improve health care. OBJECTIVE: To design and validate a questionnaire to assess the satisfaction of the care received in a Rehabilitation Department. MATERIAL AND METHODS: A cross-sectional study was carried out in the Rehabilitation Department of the Complejo Asistencial Universitario de Salamanca (CAUSA). A questionnaire was designed and prepared by experts using the Delphi technique. For the face validity, a pilot study was used using focal groups (doctors, nursing staff, physiotherapists, occupational therapists, and patients). An evaluation was made of the reliability (intraclass correlation coefficient) and internal consistency (Cronbach alpha). In a second stage, it was completed by 207 patients. The questionnaire consisted of 24 items that evaluated 4 dimensions: care/relationship, information/treatment, infrastructure, and general evaluation. RESULTS: A Cronbach alpha and intraclass correlation of greater than 0.8 was obtained in the first stage using a pilot test on 40 patients with a mean age of 58 years (SD ±16). The scale showed a good internal consistency in its final version (Cronbach alpha of 0.82) and an adequate stability (intraclass correlation of 0.8). CONCLUSIONS: The data obtained in the study showed that the designed questionnaire had a reliability of validity. And for this reason, it would be a valid and reliable tool for measuring the satisfaction of the care received by patients in Rehabilitation Departments.


Assuntos
Satisfação do Paciente , Reabilitação , Autorrelato , Adulto , Idoso , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
4.
Materials (Basel) ; 13(8)2020 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-32325667

RESUMO

Post-extractional implants and immediate loading protocols are becoming much more frequent in everyday clinical practice. Given the existing literature about tapered implants, the objective of this paper was to understand whether implant shape had a direct influence on the results of the insertion torque (IT) and implant stability quotient (ISQ). Seven tapered implant prototypes were developed and distributed into three groups and compared with a control cylindrical implant-VEGA by Klockner Implant System. The implants were inserted into bovine bone type III according to Lekholm and Zarb Classification. The sample size was n = 30 for the three groups. Final IT was measured with a torquemeter, and the ISQ was measured with Penguin Resonance Frequency Analysis (RFA). Modifications done to the Prototype I did not reveal higher values of the ISQ and IT when compared to VEGA. In the second group, when comparing the five prototypes (II-VI) with VEGA, it was seen that the values of the ISQ and IT were not always higher, but there were two values of the ISQ that were statistically significantly higher with the 4.0 mm diameter Prototypes II (76.3 ± 6.1) and IV (78 ± 3.7). Prototype VII was the one with higher and significant values of the ISQ and IT. In both diameters and in both variables, all differences were statistically significant enough to achieve the higher values of primary stability values (IT and ISQ). Given the limitations of this study, it can be concluded that when there is an increase of the diameter of the implant and body taper, there is an increase of the ISQ and IT, showing that the diameter of the implant is an important criteria to obtain higher values of primary stability.

5.
J Mater Sci Mater Med ; 30(8): 90, 2019 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-31346767

RESUMO

The aim of this study was to evaluate the biomechanical behavior of Bone Level dental implants with four different neck designs in contact with cortical bone. Numerical simulations were performed using a Finite Element Method (FEM) based-model. In order to verify the FEM model, the in silico results were compared with the results obtained from histological analysis performed in an in vivo study with New Zealand rabbits. FEM was performed using a computerized 3D model of Bone Level dental implants inserted in the lower jaw bone with an applied axial load of 100 N. The analysis was performed using four different implant neck designs: even surfaced, screwed, three-ring design and four-ring design. Interface are of bone growth was evaluated by analyzing the Bone-Implant-Contact (BIC) parameter obtained from in vivo histological process and analyzed by Scanning Electron Microscopy (SEM). Bone Level implants were inserted in the rabbit tibia, placing two implants per tibia. The BIC was evaluated after three and six weeks of implantation. FEM studies showed that the three-ring design presented lower values of stress distribution compared to the other studied designs. The lower levels of mechanical stress were then correlated with the in vivo studies, showing that the three-ring design presented the highest BIC value after 3 and 6 weeks of implantation. In silico and in vivo results both concluded that the implants with three-ring neck design presented the best biomechanical and histological behavior in terms of new bone formation, enhanced mechanical stability and optimum osseointegration.


Assuntos
Implantes Dentários , Planejamento de Prótese Dentária , Teste de Materiais/métodos , Animais , Parafusos Ósseos , Calibragem , Implantação Dentária Endóssea/instrumentação , Implantes Dentários/normas , Planejamento de Prótese Dentária/métodos , Planejamento de Prótese Dentária/normas , Análise de Elementos Finitos , Mandíbula/cirurgia , Osseointegração/fisiologia , Coelhos , Estresse Mecânico , Tíbia/cirurgia
6.
Biomater Sci ; 7(4): 1281-1285, 2019 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-30735211

RESUMO

In this communication we report that anchoring αvß3 or α5ß1 integrin-selective RGD peptidomimetics to titanium efficiently tunes mesenchymal stem cell response in vitro and bone growth in rat calvarial defects. Our results demonstrate that this molecular chemistry-derived approach could be successful to engineer instructive coatings for orthopedic applications.


Assuntos
Materiais Biocompatíveis/farmacologia , Osso e Ossos/efeitos dos fármacos , Células-Tronco Mesenquimais/efeitos dos fármacos , Oligopeptídeos/farmacologia , Peptidomiméticos/farmacologia , Animais , Materiais Biocompatíveis/síntese química , Materiais Biocompatíveis/química , Regeneração Óssea/efeitos dos fármacos , Integrina alfa5beta1/química , Integrina alfaVbeta3/química , Ligantes , Estrutura Molecular , Oligopeptídeos/síntese química , Oligopeptídeos/química , Peptidomiméticos/química , Ratos , Titânio/química , Titânio/farmacologia , Cicatrização/efeitos dos fármacos
7.
Molecules ; 23(7)2018 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-29996565

RESUMO

Bacterial infections represent a serious threat in modern medicine. In particular, biofilm treatment in clinical settings is challenging, as biofilms are very resistant to conventional antibiotic therapy and may spread infecting other tissues. To address this problem, biosensing technologies are emerging as a powerful solution to detect and identify bacterial pathogens at the very early stages of the infection, thus allowing rapid and effective treatments before biofilms are formed. Biosensors typically consist of two main parts, a biorecognition moiety that interacts with the target (i.e., bacteria) and a platform that transduces such interaction into a measurable signal. This review will focus on the development of impedimetric biosensors using antimicrobial peptides (AMPs) as biorecognition elements. AMPs belong to the innate immune system of living organisms and are very effective in interacting with bacterial membranes. They offer unique advantages compared to other classical bioreceptor molecules such as enzymes or antibodies. Moreover, impedance-based sensors allow the development of label-free, rapid, sensitive, specific and cost-effective sensing platforms. In summary, AMPs and impedimetric transducers combine excellent properties to produce robust biosensors for the early detection of bacterial infections.


Assuntos
Anti-Infecciosos/farmacologia , Bactérias/efeitos dos fármacos , Técnicas Biossensoriais/métodos , Peptídeos/farmacologia , Anti-Infecciosos/uso terapêutico , Infecções Bacterianas/tratamento farmacológico , Peptídeos/uso terapêutico
8.
J Mater Sci Mater Med ; 29(7): 99, 2018 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-29946992

RESUMO

Several dental implants are commercially available and new prototype design are constantly being fabricated. Nevertheless, it is still unclear what parameters of the design affect most the osseointegration of dental implants. The purpose of this study is to assess the effects of the microscopic and macroscopic design of dental implants in the osseointegration by comparing three macroscopic designs (Straumann tissue level (STD), essential cone (ECD) and prototype design (PD)) and six surface treatments. A total of 96 implants were placed in 12 minipigs. The implant stability quotient (ISQ), was assessed at the time of implantation, as well as at 2, 4 and 8 weeks. Histomorphometric and statistical analyses were conducted at the different sacrifice times, being 2, 4 and 8 weeks, to analyse the bone to implant contact (BIC), the bone area density (BAT) and the density of bone outside the thread region (ROI). The macroscopic design results showed higher ISQ values for the ECD, whereas the histomorphometric analysis showed higher ossoeintegration values for the STD. Regarding the microscopic design, both Sandblasted plus acid etching (hydrochloric/sulphuric acid) in a nitrogen atmosphere (SLActive) and Shot-blasted or bombarded with alumina particles and posterior alkaline immersion and thermal treatment (ContacTi) showed superior results in terms of osseointegration and reduced the osseointegration times from 8 weeks to 4 weeks compared to the other analysed surfaces. In conclusion, each of the macroscopic and microscopic designs need to be taken into account when designing novel dental implants to enhance the osseointegration process.


Assuntos
Implantes Dentários , Planejamento de Prótese Dentária , Osseointegração , Condicionamento Ácido do Dente , Óxido de Alumínio , Animais , Implantação Dentária/métodos , Feminino , Teste de Materiais , Propriedades de Superfície , Suínos , Porco Miniatura , Titânio
9.
Food Funct ; 9(5): 2617-2622, 2018 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-29770393

RESUMO

Gut microbiota dysbiosis alters the intestinal barrier function, increases plasma lipopolysaccharide (LPS) levels, which promotes endotoxemia, and contributes to the onset and development of colorectal cancer (CRC). We report here for the first time the reduction of plasma LPS-binding protein (LBP) levels, a marker of endotoxemia, after pomegranate consumption in newly diagnosed CRC patients.


Assuntos
Proteínas de Transporte/sangue , Neoplasias Colorretais/sangue , Neoplasias Colorretais/dietoterapia , Endotoxemia/sangue , Lythraceae/metabolismo , Glicoproteínas de Membrana/sangue , Proteínas de Fase Aguda , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/sangue , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/metabolismo , Endotoxemia/diagnóstico , Biomarcadores Ambientais , Feminino , Frutas/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade
10.
Colloids Surf B Biointerfaces ; 169: 30-40, 2018 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-29747028

RESUMO

Strategies to inhibit initial bacterial adhesion are extremely important to prevent infection on biomaterial surfaces. However, the simultaneous attraction of desired eukaryotic cells remains a challenge for successful biomaterial-host tissue integration. Here we describe a method for the development of a trifunctional coating that repels contaminating bacteria, kills those that adhere, and promotes osteoblast adhesion. To this end, titanium surfaces were functionalized by electrodeposition of an antifouling polyethylene glycol (PEG) layer and subsequent binding of a peptidic platform with cell-adhesive and bactericidal properties. The physicochemical characterization of the samples via SEM, contact angle, FTIR and XPS analysis verified the successful binding of the PEG layer and the biomolecules, without altering the morphology and topography of the samples. PEG coatings inhibited protein adsorption and osteoblast-like (SaOS-2) attachment; however, the presence of cell adhesive domains rescued osteoblast adhesion, yielding higher values of cell attachment and spreading compared to controls (p < 0.05). Finally, the antibacterial potential of the coating was measured by live/dead assays and SEM using S. sanguinis as a model of early colonizer in oral biofilms. The presence of PEG layers significantly reduced bacterial attachment on the surfaces (p < 0.05). This antibacterial potential was further increased by the bactericidal peptide, yielding values of bacterial adhesion below 0.2% (p < 0.05). The balance between the risk of infection and the optimal osteointegration of a biomaterial is often described as "the race for the surface", in which contaminating bacteria and host tissue cells compete to colonize the implant. In the present work, we have developed a multifunctional coating for a titanium surface that promotes the attachment and spreading of osteoblasts, while very efficiently inhibits bacterial colonization, thus holding promise for application in bone replacing applications.


Assuntos
Antibacterianos/farmacologia , Aderência Bacteriana/efeitos dos fármacos , Adesão Celular/efeitos dos fármacos , Streptococcus sanguis/efeitos dos fármacos , Titânio/farmacologia , Antibacterianos/química , Biofilmes/efeitos dos fármacos , Humanos , Testes de Sensibilidade Microbiana , Tamanho da Partícula , Propriedades de Superfície , Titânio/química , Células Tumorais Cultivadas
11.
Gac Med Mex ; 153(Supl. 2): S72-S81, 2017.
Artigo em Espanhol | MEDLINE | ID: mdl-29099102

RESUMO

Objective: To determine the effect of melatonin (MEL) administration on ciclooxigenase 2 (COX-2) activity and serum concentration of nitric oxide metabolites, lipoperoxides and glutathione peroxidase (GPx) activity in patients with Parkinson's disease. Methods: Prospective double-blind randomized clinical pilot trial. 13 patients were included and two groups were formed: MEL at doses of 25 mg orally every 12 hours for 12 months and placebo with corn starch. Patients were assessed using the Unified Parkinson's Disease Scale. A blood sample was taken at baseline and every 3 months until 12 months. Results: COX-2 activity decreased as did nitrates/nitrites (3, 6 and 9 months) and lipoperoxides (9 and 12 months); GPx exhibited no significant differences.


Assuntos
Antioxidantes/farmacologia , Ciclo-Oxigenase 2/metabolismo , Glutationa Peroxidase/sangue , Peróxidos Lipídicos/sangue , Melatonina/farmacologia , Óxido Nítrico/metabolismo , Doença de Parkinson/metabolismo , Antioxidantes/administração & dosagem , Método Duplo-Cego , Humanos , Melatonina/administração & dosagem , Estresse Oxidativo , Projetos Piloto , Estudos Prospectivos
12.
Mater Sci Eng C Mater Biol Appl ; 64: 1-10, 2016 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-27127022

RESUMO

Roughness and topographical features are the most relevant of the surface properties for a dental implant for its osseointegration. For that reason, we studied the four surfaces more used in titanium dental implants: machined, sandblasted, acid etching and sandblasted plus acid etching. The roughness and wettability (contact angle and surface free energy) was studied by means 3D-interferometric microscope and sessile drop method. Normal human gingival fibroblasts (HGF) were obtained from small oral mucosa biopsies and were used for cell cultures. To analyze cell integrity, we first quantified the total amount of DNA and LDH released from dead cells to the culture medium. Then, LIVE/DEAD assay was used as a combined method assessing cell integrity and metabolism. All experiments were carried out on each cell type cultured on each Ti material for 24h, 48h and 72h. To evaluate the in vivo cell adhesion capability of each Ti surface, the four types of discs were grafted subcutaneously in 5 Wistar rats. Sandblasted surfaces were significantly rougher than acid etching and machined. Wettability and surface free energy decrease when the roughness increases in sand blasted samples. This fact favors the protein adsorption. The DNA released by cells cultured on the four Ti surfaces did not differ from that of positive control cells (p>0.05). The number of cells per area was significantly lower (p<0.05) in the sand-blasted surface than in the machined and surface for both cell types (7±2 cells for HGF and 10±5 cells for SAOS-2). The surface of the machined-type discs grafted in vivo had a very small area occupied by cells and/or connective tissue (3.5%), whereas 36.6% of the sandblasted plus acid etching surface, 75.9% of sandblasted discs and 59.6% of acid etching discs was covered with cells and connective tissue. Cells cultured on rougher surfaces tended to exhibit attributes of more differentiated osteoblasts than cells cultured on smoother surfaces. These surface properties justify that the sandblasted implants is able to significantly increase bone contact and bone growth with very good osseointegration results in vivo.


Assuntos
Implantes Dentários , Fibroblastos/metabolismo , Gengiva/metabolismo , Teste de Materiais , Titânio , Animais , Sobrevivência Celular , Corrosão Dentária , Fibroblastos/citologia , Gengiva/citologia , Humanos , Ratos , Ratos Wistar , Molhabilidade
13.
ACS Appl Mater Interfaces ; 8(4): 2517-25, 2016 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-26735900

RESUMO

Since metallic biomaterials used for bone replacement possess low bioactivity, the use of cell adhesive moieties is a common strategy to improve cellular response onto these surfaces. In recent years, the use of recombinant proteins has emerged as an alternative to native proteins and short peptides owing to the fact that they retain the biological potency of native proteins, while improving their stability. In the present study, we investigated the biological effect of two different recombinant fragments of fibronectin, spanning the 8-10th and 12-14th type III repeats, covalently attached to a new TiNbHf alloy using APTES silanization. The fragments were studied separately and mixed at different concentrations and compared to a linear RGD, a cyclic RGD and the full-length fibronectin protein. Cell culture studies using rat mesenchymal stem cells demonstrated that low to medium concentrations (30% and 50%) of type III 8-10th fragment mixed with type III 12-14th fragment stimulated cell spreading and proliferation compared to RGD peptides and the fragments separately. On the other hand, type III 12-14th fragment alone or mixed at low volume percentages ≤50% with type III 8-10th fragment increased alkaline phosphatase levels compared to the other molecules. These results are significant for the understanding of the role of fibronectin recombinant fragments in cell responses and thus to design bioactive coatings for biomedical applications.


Assuntos
Ligas/farmacologia , Fibronectinas/farmacologia , Células-Tronco Mesenquimais/citologia , Proteínas Recombinantes/farmacologia , Fosfatase Alcalina/metabolismo , Animais , Adesão Celular/efeitos dos fármacos , Contagem de Células , Diferenciação Celular/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Forma Celular/efeitos dos fármacos , Háfnio/farmacologia , Humanos , Células-Tronco Mesenquimais/efeitos dos fármacos , Nióbio/farmacologia , Espectroscopia Fotoeletrônica , Técnicas de Microbalança de Cristal de Quartzo , Ratos Endogâmicos Lew , Titânio/farmacologia
14.
Materials (Basel) ; 9(6)2016 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-28773526

RESUMO

A bioactive layer, free of nickel, has been performed for its greater acceptability and reliability in clinical applications for NiTi shape memory alloys. In the first step, a safe barrier against Ni release has been produced on the surface by means of a thicker rutile/anastase protective layer free of nickel. In the second step, a sodium alkaline titanate hydrogel, which has the ability to induce apatite formation, has been performed from oxidized surface. An improvement of host tissue-implant integration has been achieved in terms of Ni ions release and the bioactivity of the treated NiTi alloys has been corroborated with both in vitro and in vivo studies. The transformation temperatures (As, Af, Ms, and Mf), as well as the critical stresses (σß⇔M), have been slightly changed due to this surface modification. Consequently, this fact must be taken into account in order to design new surface modification on NiTi implants.

15.
Biomaterials ; 71: 132-144, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26322724

RESUMO

Hernia repair is one of the most common operations in general surgery, and its associated complications typically relate to infections, among others. The loading of antibiotics to surgical meshes to deliver them locally in the abdominal hernia repair site can be one way to manage infections associated with surgical implants. However, the amount of drug loaded is restricted by the low wettability of polypropylene (PP). In this work, plasma has been used to tailor the surface properties of PP meshes to obtain high loading of ampicillin while conserving the desired biological properties of the unmodified samples and conferring them with antibacterial activity. It was demonstrated that the new surface chemistry and improved wettability led to 3-fold higher antibiotic loading. Subsequently, a PEG-like dry coating was deposited from tetraglyme with low-pressure plasma which allowed maintaining the high drug loading and kept cell properties such as chemotaxis, adhesion and morphology to the same levels as the untreated ones which have shown long-standing clinical success.


Assuntos
Antibacterianos/administração & dosagem , Polimerização , Polipropilenos , Telas Cirúrgicas , Animais , Linhagem Celular , Humanos , Camundongos , Microscopia Eletrônica de Varredura , Propriedades de Superfície
16.
J Biomater Appl ; 30(2): 171-81, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25805057

RESUMO

Nowadays, one of the main challenges in metal implants for bone substitution is the achievement of an elastic modulus close to that of human cortical bone as well as to provide an adequate interaction with the surrounding tissue avoiding in vivo foreign body reaction. From this perspective, a new Ti-based alloy has been developed with Nb and Hf as alloying elements which are known as non-toxic and with good corrosion properties. The microstructure, mechanical behaviour and the physicochemical properties of this novel titanium alloy have been studied. Relationship of surface chemistry and surface electric charge with protein adsorption and cell adhesion has been evaluated due to its role for understanding the mechanism of biological interactions with tissues. The Ti25Nb21Hf alloy presented a lower elastic modulus than commercial alloys with a superior ultimate strength and yield strength than CP-Ti and very close to Ti6Al4V. It also exhibited good corrosion resistance. Furthermore, the results revealed that it had no cytotoxic effect on rat mesenchymal stem cells and allowed protein adsorption and cell adhesion. The experimental results make this alloy a promising material for bone substitution or for biomedical devices.


Assuntos
Ligas , Materiais Biocompatíveis , Desenvolvimento Ósseo , Engenharia Tecidual , Adsorção , Animais , Adesão Celular , Células Cultivadas , Fibronectinas/química , Humanos , Teste de Materiais , Células-Tronco Mesenquimais/citologia , Ratos , Ratos Endogâmicos Lew , Propriedades de Superfície , Molhabilidade , Difração de Raios X
17.
J Mater Sci Mater Med ; 26(2): 75, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25631272

RESUMO

The objective of this study is assessing the influence of the use of different drill types and external irrigation on heat generation in the bone. In-vitro study to compare two different sequences for implant-bed preparation by means of two stainless steels: precipitation-hardening stainless steel (AISI 420B) (K drills), and martensitic stainless steel (AISI 440) (S drills). Besides, the drilled sequences were realized without irrigation, and with external irrigation by means of normal saline solution at room temperature. The study was realized on bovine ribs using: K without irrigation (KSI) and with irrigation (KCI) and S without irrigation (SSI) and with irrigation (SCI) with five drills for each system. Each drill was used 100 times. Bone temperature was measured with a thermocouple immediately after drilled. Average bone temperature with irrigation was for K drills 17.58±3.32 °C and for S drills 16.66±1.30 °C. Average bone temperature without irrigation was for K drills 23.58±2.94 °C and for S drills 19.41±2.27 °C. Statistically significant differences were found between K without irrigation versus S with irrigation and K with irrigation (p<0.05, Bonferroni correction). Lower temperature variation coefficient throughout the 50 measurements was observed in irrigated groups (K=5.6%, S=5.1% vs. without irrigation groups K=9.4%, S=9.3%). The first K drill generated more heat than the remaining drills. No significant differences were detected among temperature values in any of the analyzed drill groups. Unlike irrigation, drill use and type were observed to have no significant impact on heat generation. The stainless steel AISI 420B presents better mechanical properties and corrosion resistance than AISI440.


Assuntos
Implantação Dentária Endóssea/instrumentação , Implantação Dentária Endóssea/métodos , Implantes Dentários , Aço Inoxidável/química , Irrigação Terapêutica/métodos , Transferência de Energia , Desenho de Equipamento , Análise de Falha de Equipamento , Fricção , Temperatura Alta , Irrigação Terapêutica/instrumentação
18.
J Biomed Mater Res B Appl Biomater ; 103(3): 495-502, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24910134

RESUMO

A biocompatible new titanium alloy Ti-16Hf-25Nb with low elastic modulus (45 GPa) and the use of short bioadhesive peptides derived from the extracellular matrix have been studied. In terms of cell adhesion, a comparative study with mixtures of short peptides as RGD (Arg-Gly-Asp)/PHSRN (Pro-His-Ser-Arg-Asn) and RGD (Arg-Gly-Asp)/FHRRIKA (Phe-His-Arg-Arg-Ile-Lys-Ala) have been carried out with rat mesenchymal cells. The effect of these mixtures of short peptides have already been studied but there are no comparative studies between them. Despite the wide variety of silane precursors available for surface modification in pure titanium, the majority of studies have used aminosilanes, in particular 3-minopropyltriethoxysilane (APTES). Nevertheless, the 3-chloropropyltriethoxysilane (CPTES) is, recently, proposed by other authors. Unlike APTES, CPTES does not require an activation step and offers the potential to directly bind the nucleophilic groups present on the biomolecule (e.g., amines or thiols). Since the chemical surface composition of this new alloy could be different to that pure titanium, both organosilanes have been compared and characterized by means of a complete surface characterization using contact angle goniometry and X-ray photoelectron spectroscopy.


Assuntos
Ligas/química , Materiais Revestidos Biocompatíveis/química , Módulo de Elasticidade , Propilaminas/química , Silanos/química , Ligas/farmacologia , Animais , Adesão Celular/efeitos dos fármacos , Células Cultivadas , Materiais Revestidos Biocompatíveis/farmacologia , Teste de Materiais , Células-Tronco Mesenquimais , Peptídeos , Espectroscopia Fotoeletrônica , Ratos , Propriedades de Superfície , Molhabilidade
19.
J Mech Behav Biomed Mater ; 39: 79-86, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25108271

RESUMO

The generation of titanium foams is a promising strategy for modifying the mechanical properties of intervertebral reinforcements. Thus, the aim of this study was to compare the in vitro biological response of Ti6Al4V alloys with different pore sizes for use in intervertebral implants in terms of the adhesion, proliferation, and differentiation of pre-osteoblastic cells. We studied the production of Ti6Al4V foams by powder metallurgy and the biological responses to Ti6Al4V foams were assessed in terms of different pore interconnectivities and elastic moduli. The Ti6Al4V foams obtained had similar porosities of approximately 34%, but different pore sizes (66 µm for fine Ti6Al4V and 147 µm for coarse Ti6Al4V) due to the sizes of the microsphere used. The Ti6Al4V foams had a slightly higher Young׳s modulus compared with cancellous bone. The dynamic mechanical properties of the Ti6Al4V foams were slightly low, but these materials can satisfy the requirements for intervertebral prosthesis applications. The cultured cells colonized both sizes of microspheres near the pore spaces, where they occupied almost the entire area of the microspheres when the final cell culture time was reached. No statistical differences in cell proliferation were observed; however, the cells filled the pores on fine Ti6Al4V foams but they only colonized the superficial microspheres, whereas the cells did not fill the pores on coarse Ti6Al4V foams but they were distributed throughout most of the material. In addition, the microspheres with wide pores (coarse Ti6Al4V) stimulated higher osteoblast differentiation, as demonstrated by the Alcaline Phosphatase (ALP) activity. Our in vitro results suggest that foams with wide pore facilitate internal cell colonization and stimulate osteoblast differentiation.


Assuntos
Materiais Biocompatíveis/química , Osteoblastos/citologia , Titânio/química , Ligas , Diferenciação Celular , Linhagem Celular Tumoral , Elasticidade , Humanos , Teste de Materiais , Microscopia Eletrônica de Varredura , Microesferas , Osteoblastos/efeitos dos fármacos , Osteoblastos/metabolismo , Porosidade , Próteses e Implantes , Estresse Mecânico
20.
Mater Sci Eng C Mater Biol Appl ; 42: 691-5, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25063170

RESUMO

ß-Type titanium alloys with a low elastic modulus are a potential strategy to reduce stress shielding effect and to enhance bone remodeling in implants used to substitute failed hard tissue. For biomaterial application, investigation on the mechanical behavior, the corrosion resistance and the cell response is required. The new Ti25Nb16Hf alloy was studied before and after 95% cold rolling (95% C.R.). The mechanical properties were determined by tensile testing and its corrosion behavior was analyzed by potentiostatic equipment in Hank's solution at 37°C. The cell response was studied by means of cytotoxicity evaluation, cell adhesion and proliferation measurements. The stress-strain curves showed the lowest elastic modulus (42GPa) in the cold worked alloy and high tensile strength, similar to that of Ti6Al4V. The new alloy exhibited better corrosion resistance in terms of open circuit potential (EOCP), but was similar in terms of corrosion current density (iCORR) compared to Ti grade II. Cytotoxicity studies revealed that the chemical composition of the alloy does not induce cytotoxic activity. Cell studies in the new alloy showed a lower adhesion and a higher proliferation compared to Ti grade II presenting, therefore, mechanical features similar to those of human cortical bone and, simultaneously, a good cell response.


Assuntos
Ligas/química , Materiais Biocompatíveis/química , Elementos de Transição/química , Ligas/toxicidade , Materiais Biocompatíveis/toxicidade , Adesão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Corrosão , Módulo de Elasticidade , Humanos , Teste de Materiais , Estresse Mecânico , Elementos de Transição/toxicidade
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA