Development and characterization of ceramic-polymeric hybrid scaffolds for bone regeneration: incorporating of bioactive glass BG-58S into PDLLA matrix.

In recent years, there has been a notable surge of interest in hybrid materials within the biomedical field, particularly for applications in bone repair and regeneration. Ceramic-polymeric hybrid scaffolds have shown promising outcomes. This study aimed to synthesize bioactive glass (BG-58S) for integration into a bioresorbable polymeric matrix based on PDLLA, aiming to create a bioactive scaffold featuring stable pH levels. The synthesis involved a thermally induced phase separation process followed by lyophilization to ensure an appropriate porous structure. BG-58S characterization revealed vitreous, bioactive, and mesoporous structural properties. The scaffolds were analyzed for morphology, interconnectivity, chemical groups, porosity and pore size distribution, zeta potential, pH, in vitro degradation, as well as cell viability tests, total protein content and mineralization nodule production. The PDLLA scaffold displayed a homogeneous morphology with interconnected macropores, while the hybrid scaffold exhibited a heterogeneous morphology with smaller diameter pores due to BG-58S filling. The hybrid scaffold also demonstrated a pH buffering effect on the polymer surface. In addition to structural characteristics, degradation tests indicated that by incorporating BG-58S modified the acidic degradation of the polymer, allowing for increased total protein production and the formation of mineralization nodules, indicating a positive influence on cell culture.

Development, characterization, and biological study of bioglass coatings 45S5 and BioK on zirconia implant surfaces.

Zirconia implants are gaining attention as a viable alternative to titanium implants due to their comparable osseointegration development, improved soft tissue adaptation, and enhanced aesthetics. An encouraging avenue for improving zirconia implant properties involves the potential application of bioactive coatings to their surfaces. These coatings have shown potential for inducing hydroxyapatite formation, crucial for bone proliferation, and improving implant mechanical properties. This study aimed to evaluate the effect of coating zirconia implants with two bioactive glasses, 45S5 and BioK, on osteogenesis in vitro and osseointegration in vivo. Zirconia samples and implants were prepared using Zpex zirconia powder and blocks, respectively. The samples were divided into three groups: polished zirconia (ZRC), zirconia coated with 45S5 bioglass (Z + 45S5), and zirconia coated with BioK glass (Z + BK). Coatings were applied using a brush and sintered at 1200°C. Chemical analysis of the coatings was carried out using x-ray diffraction and Fourier Transform Infrared Spectroscopy. Surface topography and roughness were characterized using scanning electron microscopy and a roughness meter. In vitro experiments used mesenchymal cells from Wistar rat femurs, and the coated zirconia implants were found to promote cell viability, protein synthesis, alkaline phosphatase activity, and mineralization, indicating enhanced osteogenesis. In vivo experiments with 18 rats showed positive results for bone formation and osseointegration through histological and histomorphometric analysis and a push-out test. The findings indicate that bioactive glass coatings have the potential to improve cell differentiation, bone formation, and osseointegration in zirconia implants.

Chlorinated-based bioceramics incorporated in polycaprolactone membranes.

The development of bioactive membranes with bone repair properties is great interest in the field of tissue engineering. In this study, we aimed to fabricate and characterize a composite membrane composed of sol-gel synthesized bioceramics and electrospun polycaprolactone (PCL) fibers for bone tissue regeneration applications. The bioceramics were prepared using the sol-gel method with nitrate (N) and chloride (CL) as precursors. PCL and bioceramic solutions were electrospun to obtain ultrafine fiber mats. Raman spectroscopy, x-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were used to characterize the materials. The results showed that both chlorinated and non-chlorinated bioceramics contained NBOs (non-bridge bonds) and crystallized the α-wollastonite phase, with the chlorinated version doing so at lower temperatures. In vitro tests were performed to evaluate cytotoxicity, cell adhesion, and mineralized matrix formation on the membranes. The composite membranes showed improved cell viability and promoted mineralization nodules formation. This study presents a promising approach for the development of bioactive membranes for bone tissue engineering, with potential applications in bone regeneration therapies.

Carbon fiber: Characterization and evaluation of the inflammatory response and toxicity in rats.

This study aimed to evaluate the Carbon Fiber obtained from PAN textile and cotton fiber in their different forms of presentation: non-activated carbon fiber felt (NACFF), activated carbon fiber felt (ACFF), silver activated carbon fiber felt (Ag-ACFF), and activated carbon fiber tissue (ACFT), to obtain scaffolds as a potential material with properties related to the synthetic bone graft. Characterization tests performed: surface wettability, traction, swelling, and in vivo tests: evaluation of the inflammatory response by implanting the materials in the subcutaneous tissue of 14 Wistar rats, evaluation of collagen fibers by picrosirius red staining and assessment of toxicity in the following organs: heart, spleen, liver, and kidney. In the wettability test, NACFF and ACFT were hydrophobic (θ124° and 114°), ACFF and Ag-ACFF were hydrophilic. For maximum stress, ACFF was more resistant (2.983 ± 1.059) p < .05. In the swelling test, the Ag-ACFF and ACFF groups showed the highest absorption percentage for the PBS solution and distilled water (p < .001). The organs showed no signs of acute systemic toxicity. The implant regions showed mild to moderate inflammatory infiltrate at 7 and 21 days. Only the ACFT group did not show the maturation of type I collagen fibers in 21 days. Through the conducted analyses, the ACFT shows little potential to be indicated as a possible scaffold. Therefore NACFF, ACFF, and Ag-ACFF have the potential to be considered scaffolds due to the following characteristics presented: good absorption rate, hydrophilicity, and non-toxic.

ß-TCP/S53P4 Scaffolds Obtained by Gel Casting: Synthesis, Properties, and Biomedical Applications.

The objective of this study was to investigate the osteogenic and antimicrobial effect of bioactive glass S53P4 incorporated into ß-tricalcium phosphate (ß-TCP) scaffolds in vitro and the bone neoformation in vivo. ß-TCP and ß-TCP/S53P4 scaffolds were prepared by the gel casting method. Samples were morphologically and physically characterized through X-ray diffraction (XRD) and scanning electron microscope (SEM). In vitro tests were performed using MG63 cells. American Type Culture Collection reference strains were used to determine the scaffold's antimicrobial potential. Defects were created in the tibia of New Zealand rabbits and filled with experimental scaffolds. The incorporation of S53P4 bioglass promotes significant changes in the crystalline phases formed and in the morphology of the surface of the scaffolds. The ß-TCP/S53P4 scaffolds did not demonstrate an in vitro cytotoxic effect, presented similar alkaline phosphatase activity, and induced a significantly higher protein amount when compared to ß-TCP. The expression of Itg ß1 in the ß-TCP scaffold was higher than in the ß-TCP/S53P4, and there was higher expression of Col-1 in the ß-TCP/S53P4 group. Higher bone formation and antimicrobial activity were observed in the ß-TCP/S53P4 group. The results confirm the osteogenic capacity of ß-TCP ceramics and suggest that, after bioactive glass S53P4 incorporation, it can prevent microbial infections, demonstrating to be an excellent biomaterial for application in bone tissue engineering.

The Local Release of Teriparatide Incorporated in 45S5 Bioglass Promotes a Beneficial Effect on Osteogenic Cells and Bone Repair in Calvarial Defects in Ovariectomized Rats.

With the increase in the population's life expectancy, there has also been an increase in the rate of osteoporosis, which has expanded the search for strategies to regenerate bone tissue. The ultrasonic sonochemical technique was chosen for the functionalization of the 45S5 bioglass. The samples after the sonochemical process were divided into (a) functionalized bioglass (BG) and (b) functionalized bioglass with 10% teriparatide (BGT). Isolated mesenchymal cells (hMSC) from femurs of ovariectomized rats were differentiated into osteoblasts and submitted to in vitro tests. Bilateral ovariectomy (OVX) and sham ovariectomy (Sham) surgeries were performed in fifty-five female Wistar rats. After a period of 60 days, critical bone defects of 5.0 mm were created in the calvaria of these animals. For biomechanical evaluation, critical bone defects of 3.0 mm were performed in the tibias of some of these rats. The groups were divided into the clot (control) group, the BG group, and the BGT group. After the sonochemical process, the samples showed modified chemical topographic and morphological characteristics, indicating that the surface was chemically altered by the functionalization of the particles. The cell environment was conducive to cell adhesion and differentiation, and the BG and BGT groups did not show cytotoxicity. In addition, the experimental groups exhibited characteristics of new bone formation with the presence of bone tissue in both periods, with the BGT group and the OVX group statistically differing from the other groups (p < 0.05) in both periods. Local treatment with the drug teriparatide in ovariectomized animals promoted positive effects on bone tissue, and longitudinal studies should be carried out to provide additional information on the biological performance of the mutual action between the bioglass and the release of the drug teriparatide.

Polycaprolactone/chlorinated bioglass scaffolds doped with Mg and Li ions: Morphological, physicochemical, and biological analysis.

The objective was to synthesize and characterize fine polycaprolactone (PCL) fibers associated with a new 58S bioglass obtained by the precipitated sol-gel route, produced by the electrospinning process in order to incorporate therapeutic ions (Mg and Li). In PCL/acetone solutions were added 7% pure bioglass, bioglass doped with Mg(NO3 )2 and Li2 CO3 and were subjected to electrospinning process. The fibers obtained were characterized morphologically, chemically and biologically. The results showed the presence of fine fibers at the nanometric scale and with diameters ranging from 0.67 to 1.92 µm among groups. Groups containing bioglass showed particles both inside and on the surface of the fibers. The components of the polymer, bioglass and therapeutic ions were present in the fibers produced. The produced fibers showed cell viability and induced the formation of mineralization nodules. It was observed the applicability of that methodology in making an improved biomaterial, which adds the osteoinductive properties of the bioglass to PCL and to those of therapeutic ions, applicable to guided bone regeneration.

Electrospun polylactic acid scaffolds with strontium- and cobalt-doped bioglass for potential use in bone tissue engineering applications.

The development of nanoscale biomaterials associated with polymers has been growing over the years, due to their important structural characteristics for applications in biological systems. The present study aimed to produce and test polymeric scaffolds composed of polylactic acid (PLA) fibers associated with a 58S bioglass doped with therapeutic ions for use in tissue engineering. Three 58S Bioglass was obtained by the sol-gel route, pure and doped with 5% strontium and cobalt ions. Solutions of 7% PLA was used as control and added the three different bioglass, 4% of 58S bioglass (PLA-BG), 4% bioglass-doped strontium (PLA-BGSr) and 4% bioglass-doped cobalt (PLA-BGCo). Scaffolds were produced through electrospinning process, and was characterized chemical and morphologically. The in vitro tests were performed using mesenchymal cells cultures from femurs of nine rats, grown in osteogenic supplemented total culture medium. After osteoblastic differentiation induction cell viability, alkaline phosphatase activity, total protein content quantification, and visualization of mineralization nodule tests were performed. Analysis of normal distribution used the Shapiro-Wilk test (nanofibers diameter and biological assay). Data were compared using the Kruskal-Wallis nonparametric test (p = 0.05). The bioglasses produced proved to be free of nitrate, chlorinated and nano-sized, with effective incorporation of therapeutic ions in their structure. All materials showed cell viability (>70%), total protein production, and alkaline phosphatase activity. It was possible to develop polylactic acid scaffolds associated with 58S bioglass doped with therapeutic ions without cytotoxicity. Scaffolds characteristics appear to sustain its application in bone tissue engineering.

Argon plasma application on the surface of titanium implants: osseointegration study / Aplicação de plasma de argônio na superfície de implantes de titânio: estudo de osseointegração

Introduction: The development of new biomaterials with improved properties is a trend in regenerative medicine. The successful healing of implants is related to their osseointegration and the topographic geometry of their surface. Treatment with argon plasma acts on the surface of the implants, bringing several benefits to their osseointegration in the body. Material and Methods: Previously the in vivo study, the topography implants were observed by scanning electron microscopy (SEM). Following the implants were inserted in 14 male rats, and one perforation was made in the right and left tibias for implant placement without the surface treatment (control group), and with the argon plasma surface treatment (experimental group), respectively. The rats were euthanized at 4 weeks, a time in which tibia fragments were submitted for histological and histomorphometric examination, and torque removal test for comparison and analysis of osseointegration. Results: The SEM images showed the argon plasma surface treatment altered the topography. At the end of the study, both greater bone formation and better osseointegration were verified in the experimental group, and a statistically significant difference between the groups was observed. Conclusion: It was concluded that implants with this surface treatment can bring more practicality in the rehabilitation treatment, and more comfort in the patients' postoperative time (AU)

Introdução: O desenvolvimento de novos biomateriais com propriedades aprimoradas é uma tendência na medicina regenerativa. A cicatrização bem-sucedida dos implantes está relacionada à sua osseointegração e à geometria topográfica de sua superfície. O tratamento com plasma de argônio atua na superfície dos implantes, trazendo diversos benefícios para sua osseointegração no corpo. Materiais e Métodos: Antes do estudo in vivo, a topografia dos implantes foi observada por microscopia eletrônica de varredura (MEV). Em seguida, os implantes foram inseridos em 14 ratos machos, e uma perfuração foi feita nas tíbias direita e esquerda para a colocação do implante sem o tratamento de superfície (grupo controle) e com o tratamento de superfície de plasma de argônio (grupo experimental), respectivamente. Os ratos foram sacrificados após 4 semanas, momento em que fragmentos das tíbias foram submetidos a exame histológico e histomorfométrico, além do teste de remoção de torque para comparação e análise da osseointegração. Resultados: As imagens de MEV mostraram que o tratamento de superfície com plasma de argônio alterou a topografia. Ao final do estudo, foi verificada maior formação óssea e melhor osseointegração no grupo experimental, e foi observada diferença estatisticamente significativa entre os grupos. Conclusão: Concluiu-se que os implantes com esse tratamento de superfície podem trazer mais praticidade no tratamento de reabilitação e maior conforto no pós-operatório dos pacientes (AU)

Effect of radiotherapy on the differentiation and osteogenic activity of mesenchymal stem cells on dental implants / Efeito da radioterapia na diferenciação e atividade osteogênica de células-tronco mesenquimais em implantes dentários

Objective: to evaluate the differentiation and gene expression of transcripts related to osteogenesis in a primary culture of Mesenchymal Stem Cells (MSCs) derived from rat femurs submitted to radiotherapy and the installation of pure titanium implants. Material and Methods: fifty-four rats received titanium implants in both femurs and were divided into three groups: Control: implant surgery (C); Implant + immediate irradiation (IrI), and Implant + late irradiation (IrL). Euthanasia occurred 3, 14, and 49 days after surgery. The bone marrow MSCs from the femurs were isolated and cultivated. The cell viability, total protein content, alkaline phosphatase (ALP) activity, and the formation of mineralization nodules and cellular genotoxicity were analyzed. The gene expression of Alkaline Phosphatase (phoA), Collagen 1 (COL1), Runt-related transcription factor 2 (RUNX2), Osterix (OSX), Osteopontin (OPN), Integrin ß1(ITGB1), Bone Sialoprotein (BSP), Osteonectin (SPARC), Osteocalcin (Bglap), Transforming Growth Factor ß-type (TGF-ß), Granulocyte Macrophage Colony Stimulating Factor (GM-CSF), Interleukin-6 (IL-6), Apolipoprotein E (APOE) and Prostaglandin E2 synthase (PGE2) were evaluated by qRT- PCR. Results: ionizing radiation suppresses the gene expression of essential transcripts for bone regeneration, as well as cellular viability, as observed in the IrI and IrL groups. Conclusion: although this can lead to the loss of osseointegration and failure of the implant, the MSCs showed more activity at 49 days than at 3 and 14 days. (AU)

Objetivo: avaliar a diferenciação e expressão gênica de transcritos relacionados à osteogênese em cultura primária de MSCs derivadas de fêmures de ratos submetidos à radioterapia e instalação de implantes de titânio puro. Material e Métodos: cinquenta e quatro ratos receberam implantes de titânio em ambos os fêmures e foram divididos em três grupos: Controle: cirurgia de implante (C); Implante + irradiação imediata (IrI) e Implante + irradiação tardia (IrL). A eutanásia ocorreu 3, 14 e 49 dias após a cirurgia. As MSCs de medula óssea dos fêmures foram isoladas e cultivadas. Foram analisadas a viabilidade celular, teor de proteína total, atividade da fosfatase alcalina (ALP), formação de nódulos de mineralização e genotoxicidade celular. A expressão gênica de Fosfatase Alcalina (phoA), Colágeno 1 (COL1), fator de transcrição relacionado a Runt 2 (RUNX2), Osterix (OSX), Osteopontina (OPN), Integrina ß1 (ITGB1), Sialoproteína Óssea (BSP), Osteonectina (SPARC), Osteocalcina (Bglap), Fator de Crescimento Transformador tipo ß (TGF-ß), Fator Estimulante de Colônia de Granulócitos-Macrófagos (GM-CSF), Interleucina-6 (IL-6), Apolipoproteína E (APOE) e Prostaglandina E2 sintase (PGE2) foram avaliados por qRT-PCR. Resultados: a radiação ionizante suprime a expressão gênica de transcritos essenciais para a regeneração óssea, bem como a viabilidade celular, como observado nos grupos IrI e IrL. Conclusão:embora isso possa levar à perda da osseointegração e falha do implante, as MSCs apresentaram maior atividade aos 49 dias do que aos 3 e 14 dias (AU)

New teaching strategies in dentistry: an experience in a Brazilian dental school / Novas estratégias de ensino em Odontologia: experiência em uma universidade brasileira

The need for new teaching-learning strategies stems from the great change society is going through. The so-called digital natives are part of a generation that lives in a hyperactive rhythm making it increasingly difficult to adapt to traditional classrooms. In Dentistry Courses, new strategies and pedagogical tools have been used, suchas active learning methodologies. In this context, the Discipline of Histology of the Dentistry Course has been proposing the use of some innovative pedagogical strategies. This work will present the experience with team-based learning (TBL), which articulates individual (iRAT) and group activities (gRAT), stimulates the application of concepts and can articulate with other methodologies such as flipped classroom, case study and problematization. This study alsoanalysedstudents' performance in iRAT and gRAT with the application of TBLand discussed the results achieved. Itwas conducted by analysingthe scoresof 240 first-year students of the Histology course in 2016, 2017 and 2018. Student scores, individually and in groups, were statistically analysedby the paired student t-test. Comparisons were made between the iRAT and gRAT activities about gender and the full-time and night classes by the one-way ANOVA and Kruskal-Wallis test. All students obtained higher group scores when compared to individual test results (p <0.001). There was no significant difference between sexes and study period. Group performanceexceeds individual performance. From this, it can be inferred that TBL can be a good strategy to use in dentistry, as an interaction between students leads to higher performance and problem-solving capacity (AU).

A necessidade de novas estratégias de ensino-aprendizagem decorre da grande mudança pela qual a sociedade está passando. Os chamados nativos digitais fazem parte de uma geração que vive em um ritmo hiperativo tornando cada vez mais difícil a adaptação às salas de aula tradicionais. Nos cursos de Odontologia, novas estratégias e ferramentas pedagógicas têm sido utilizadas, como metodologias ativas de aprendizagem. Nesse contexto, a Disciplina de Histologia do Curso de Odontologia tem proposto a utilização de algumas estratégias pedagógicas inovadoras. Este trabalho apresentará a experiência com a aprendizagem baseada em equipe (TBL), que articula atividades individuais (iRAT) e em grupo (gRAT), estimula a aplicação de conceitos e pode se articular com outras metodologias como aula invertida, estudo de caso e problematização. Este estudo também analisou o desempenho dos alunos no iRAT egRAT com a aplicação da TBL e discutiu os resultados alcançados. Foi realizado por meio da análise das notas de 240 alunos do primeiro ano do curso de Histologia em 2016, 2017 e 2018. As notas dos alunos, individualmente e em grupos, foram analisadas estatisticamente por meio do teste t-student pareado. As comparações foram feitas entre as atividades iRAT e gRAT sobre gênero e as aulas em período integral e noturno pelo teste ANOVA one waye teste de Kruskal-Wallis. Todos os alunos obtiveram pontuações mais altas do grupo quando comparados aos resultados dos testes individuais (p <0,001). Não houve diferença significativa entre os sexos e o período de estudo. O desempenho do grupo excede o desempenho individual. A partir disso, pode-se inferirque o TBL pode ser uma boa estratégia para uso em odontologia, pois uma interação entre os alunos leva a um maior desempenho e capacidade de resolução de problemas (AU).

Influence of titanium nanotubular surfaces, produced by anodization, on the behavior of osteogenic cells: in vitro evaluation / Influência da superfície nanotubular do titânio, produzido por anodização, no comportamento de células osteogênicas: avaliação in vitro

Objective: The objective of this study was to evaluate in vitro the influence of the anodized surface of Ti35Nb7Zr alloy on the behavior of osteogenic cells, for future application in biomedical implants. Material and Methods: For the development of this research, samples of commercially pure titanium (TiCp) and samples of Ti35Nb7Zr alloy were anodized, both were characterized by scanning electron microscopy (SEM) and were plated afterwards with human osteoblast-like cells (MG63 line) (2 x 104). Cell adhesion, cytotoxicity test, formation of mineralization nodules and a comet assay were also performed in different periods. The bottom of the plate was used as a control, without a sample. Results: SEM analysis showed that the topography of both samples presented surfaces covered by nanotubes. Cellular morphology exhibited spreading in both samples proposing an intimate cell- material liaison. After 3 days, the Ti35Nb7Zr group exhibited greater cell viability than the TiCp group (p<0.01). Regarding calcium content, there was no statistical difference between the anodized groups, but there was a difference between the experimental groups and the control group (p<0.01). In the comet assay, the percentage of DNA in the comet tail did not exhibit any significant difference (p>0.05) among the groups in the evaluated periods. Conclusion: It was concluded that this process of anodization was efficient to form nanotubes, as well as promote a positive influence on the behavior of osteogenic cells without promoting cell damage. (AU)

Objetivo: O objetivo deste estudo foi avaliar in vitro a influência da superfície anodizada da liga Ti35Nb7Zr no comportamento de células osteogênicas, para futura aplicação em implantes biomédicos. Material e Métodos: Para o desenvolvimento desta pesquisa, amostras de titânio comercialmente puro (TiCp) e amostras da liga Ti35Nb7Zr foram anodizadas, ambas foram caracterizadas por microscopia eletrônica de varredura (MEV) e posteriormente plaqueadas com células semelhantes a osteoblastos humanos (linha MG63) (2 x 104). Foram realizados em diferentes períodos a adesão celular, teste de citotoxicidade, formação de nódulos de mineralização e ensaio do cometa. O fundo da placa foi usado como controle, sem amostra. Resultados: A análise em MEV mostrou que a topografia de ambas as amostras apresentava superfícies cobertas por nanotubos. A morfologia celular exibiu espalhamento em ambas as amostras, propondo uma ligação íntima célula-material. Após 3 dias, o grupo Ti35Nb7Zr exibiu maior viabilidade celular do que o grupo TiCp (p<0.01). Em relação ao teor de cálcio, não houve diferença estatística entre os grupos anodizados, mas houve diferença entre os grupos experimentais e o grupo controle (p<0.01). No ensaio do cometa, a porcentagem de DNA na cauda do cometa não apresentou diferença significativa (p> 0.05) entre os grupos nos períodos avaliados. Conclusão:Concluiu-se que esse processo de anodização foi eficiente para formar nanotubos, além de promover uma influência positiva no comportamento das células osteogênicas sem promover dano celular. (AU)

Bioactivity of an Experimental Dental Implant with Anodized Surface.

BACKGROUND: Several studies proved that anodic oxidation improves osseointegration. This study aimed to optimize osseointegration through anodization in dental implants, obtaining anatase phase and controlled nanotopography. METHODS: The division of the groups with 60 titanium implants was: control (CG); sandblasted (SG); anodized (AG): anodized pulsed current (duty cycle 30%, 30 V, 0.2 A and 1000 Hz). Before surgery, surface characterization was performed using Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), X-ray Dispersive Energy Spectroscopy (EDS) and Raman Spectroscopy. For in vivo tests, 10 New Zealand white rabbits received an implant from each group. The sacrifice period was 2 and 6 weeks (n = 5) and the specimens were subjected to computed microtomography (µCT) and reverse torque test. RESULTS: AFM and SEM demonstrated a particular nanotopography on the surface in AG; the anatase phase was proved by Raman spectroscopy. In the µCT and in the reverse torque test, the AG group presented better results than the other groups. CONCLUSION: The chemical composition and structure of the TiO2 film were positively affected by the anodizing technique, intensifying the biological characteristics in osseointegration.

Characterization of Optimized TiO2 Nanotubes Morphology for Medical Implants: Biological Activity and Corrosion Resistance.

BACKGROUND: Nanostructured surface modifications of Ti-based biomaterials are moving up from a highly-promising to a successfully-implemented approach to developing safe and reliable implants. METHODS: The study's main objective is to help consolidate the knowledge and identify the more suitable experimental strategies related to TiO2 nanotubes-modified surfaces. In this sense, it proposes the thorough investigation of two optimized nanotubes morphologies in terms of their biological activity (cell cytotoxicity, alkaline phosphatase activity, alizarin red mineralization test, and cellular adhesion) and their electrochemical behavior in simulated body fluid (SBF) electrolyte. Layers of small-short and large-long nanotubes were prepared and investigated in their amorphous and crystallized states and compared to non-anodized samples. RESULTS: Results show that much more than the surface area development associated with the nanotubes' growth; it is the heat treatment-induced change from amorphous to crystalline anatase-rutile structures that ensure enhanced biological activity coupled to high corrosion resistance. CONCLUSION: Compared to both non-anodized and amorphous nanotubes layers, the crystallized nano-structures' outstanding bioactivity was related to the remarkable increase in their hydrophilic behavior, while the enhanced electrochemical stability was ascribed to the thickening of the dense rutile barrier layer at the Ti surface beneath the nanotubes.

Electrospun Poly(butylene-adipate-co-terephthalate)/Nano-hyDroxyapatite/Graphene Nanoribbon Scaffolds Improved the In Vivo Osteogenesis of the Neoformed Bone.

Electrospun ultrathin fibrous scaffold filed with synthetic nanohydroxyapatite (nHAp) and graphene nanoribbons (GNR) has bioactive and osteoconductive properties and is a plausible strategy to improve bone regeneration. Poly(butylene-adipate-co-terephthalate) (PBAT) has been studied as fibrous scaffolds due to its low crystallinity, faster biodegradability, and good mechanical properties; however, its potential for in vivo applications remains underexplored. We proposed the application of electrospun PBAT with high contents of incorporated nHAp and nHAp/GNR nanoparticles as bone grafts. Ultrathin PBAT, PBAT/nHAp, and PBAT/nHAp/GNR fibers were produced using an electrospinning apparatus. The produced fibers were characterized morphologically and structurally using scanning electron (SEM) and high-resolution transmission electron (TEM) microscopies, respectively. Mechanical properties were analyzed using a texturometer. All scaffolds were implanted into critical tibia defects in rats and analyzed after two weeks using radiography, microcomputed tomography, histological, histomorphometric, and biomechanical analyses. The results showed through SEM and high-resolution TEM characterized the average diameters of the fibers (ranged from 0.208 µm ± 0.035 to 0.388 µm ± 0.087) and nHAp (crystallite around 0.28, 0.34, and 0.69 nm) and nHAp/GNR (200-300 nm) nanoparticles distribution into PBAT matrices. Ultrathin fibers were obtained, and the incorporated nHAp and nHAp/GNR nanoparticles were well distributed into PBAT matrices. The addition of nHAp and nHAp/GNR nanoparticles improved the elastic modulus of the ultrathin fibers compared to neat PBAT. High loads of nHAp/GNR (PBATnH5G group) improved the in vivo lamellar bone formation promoting greater radiographic density, trabecular number and stiffness in the defect area 2 weeks after implantation than control and PBAT groups.

Evaluation of pulsed electromagnetic field protocols in implant osseointegration: in vivo and in vitro study.

OBJECTIVES: The present study aims to evaluate two protocols of pulsed electromagnetic field (PEMF) on osseointegration and establish one that addresses ideal parameters for its use in dentistry, especially in the optimization of the implants osseointegration process. MATERIALS AND METHODS: Sixty male rats (Wistar) were allocated into three experimental groups: control (GC), test A (GTA, 3 h exposed), and test B (GTB, 1 h exposed). All animals received titanium implants in both tibias, and PEMF application (15 Hz, ± 1 mT, 5 days/week) occurred only in the test groups. They were euthanized at 03, 07, 21, and 45 days after PEMF therapy. Removal torque, histomorphometric measurements, three-dimensional radiographic evaluation, and in vitro biological assay analyses were performed. RESULTS: GTB showed better results compared with GTA in removal torque tests, in bone volume and bone mineral density, cell viability, total protein content, and mineralization nodules (p < 0.05). GTA showed better performance in trabecular bone thickness and cell proliferation compared with GTB (p < 0.05), especially at osseointegration early periods. In the histomorphometric analysis and number of trabeculae, there were no differences in the test groups. CONCLUSION: PEMF as a biostimulator was effective in optimizing the events in bone tissue that lead to osseointegration, especially when applied for a shorter time and in the initial periods of bone healing. CLINICAL RELEVANCE: The PEMF therapy is an effective alternative method for optimizing bone healing.

Biological and microbiological interactions of Ti-35Nb-7Zr alloy and its basic elements on bone marrow stromal cells: good prospects for bone tissue engineering.

BACKGROUND: An effective biomaterial for bone replacement should have properties to avoid bacterial contamination and promote bone formation while inducing rapid cell differentiation simultaneously. Bone marrow stem cells are currently being investigated because of their known potential for differentiation in osteoblast lineage. This makes these cells a good option for stem cell-based therapy. We have aimed to analyze, in vitro, the potential of pure titanium (Ti), Ti-35Nb-7Zr alloy (A), niobium (Nb), and zirconia (Zr) to avoid the microorganisms S. aureus (S.a) and P. aeruginosa (P.a). Furthermore, our objective was to evaluate if the basic elements of Ti-35Nb-7Zr alloy have any influence on bone marrow stromal cells, the source of stem cells, and observe if these metals have properties to induce cell differentiation into osteoblasts. METHODS: Bone marrow stromal cells (BMSC) were obtained from mice femurs and cultured in osteogenic media without dexamethasone as an external source of cell differentiation. The samples were divided into Ti-35Nb-7Zr alloy (A), pure titanium (Ti), Nb (niobium), and Zr (zirconia) and were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). After predetermined periods, cell interaction, cytotoxicity, proliferation, and cell differentiation tests were performed. For monotypic biofilm formation, standardized suspensions (106 cells/ml) with the microorganisms S. aureus (S.a) and P. aeruginosa (P.a) were cultured for 24 h on the samples and submitted to an MTT test. RESULTS: All samples presented cell proliferation, growth, and spreading. All groups presented cell viability above 70%, but the alloy (A) showed better results, with statistical differences from Nb and Zr samples. Zr expressed higher ALP activity and was statistically different from the other groups (p < 0.05). In contrast, no statistical difference was observed between the samples as regards mineralization nodules. Lower biofilm formation of S.a and P.a. was observed on the Nb samples, with statistical differences from the other samples. CONCLUSION: Our results suggest that the basic elements present in the alloy have osteoinductive characteristics, and Zr has a good influence on bone marrow stromal cell differentiation. We also believe that Nb has the best potential for reducing the formation of microbial biofilms.

Synergistic effect of adding bioglass and carbon nanotubes on poly (lactic acid) porous membranes for guided bone regeneration.

Polymer membranes have been widely used in guided bone regeneration (GBR), especially when it comes to their use in dentistry. Poly (lactic acid) (PLA) have good mechanical properties such as flexibility, which allows the material to be moldable and also has biocompatibility and biodegradation. Besides that, bioglass (BG) incorporated into the polymer matrix can promote osteoinduction properties and osteoconduction properties to the polymer-ceramic biocomposite. The membranes are also required to exhibit antimicrobial activity to prevent or control the proliferation of pathogenic microorganisms, and the addition of carbon nanotubes (CNT) can assist in this property. The porous membranes of PLA with the addition of different contents of BG and CNT were obtained by solvent casting in controlled humidity method, and the synergistic effect of the addition of both fillers were investigated. The membranes showed pores (3-11 µm) on their surface. The addition of 5 wt% BG causes an increase in the surface porosity and bioactivity properties of the PLA. The agar diffusion test showed antimicrobial activity in the membranes with addition of CNT. In vitro results showed that the porous membranes were not cytotoxic and allowed cell activity and differentiation. Thus, BG collaborated to increase biological activity while CNT contributed to microbial activity, creating a synergistic effect on PLA porous membranes, being this effect more evident for PLA/5BG/1.0CNT. These results indicated a promising use of this new biomaterial for the production of porous membranes for GBR.

Scaffolds of PCL combined to bioglass: synthesis, characterization and biological performance.

Biomaterials may be useful in filling lost bone portions in order to restore balance and improve bone regeneration. The objective of this study was to produce polycaprolactone (PCL) membranes combined with two types of bioglass (Sol-Gel and melt-quenched) and determine their physical and biological properties. Membranes were produced through electrospinning. This study presented three experimental groups: pure PCL membranes, PCL-Melt-Bioglass and PCL-Sol-gel-Bioglass. Membranes were characterized using Scanning Electron Microscopy, Fourier Transform Infrared Spectrophotometry (FTIR), Energy-Dispersive Spectroscopy and Zeta Potential. The following in vitro tests were performed: MTT assay, alkaline phosphatase activity, total protein content and mineralization nodules. Twenty-four male rats were used to observe biological performance through radiographic, fracture energy, histological and histomorphometric analyses. The physical and chemical analysis results showed success in manufacturing bioactive membranes which significantly enhanced cell viability and osteoblast differentiation. The new formed bone from the in vivo experiment was similar to that observed in the control group. In conclusion, the electrospinning enabled preparing PCL membranes with bioglass incorporated into the structure and onto the surface of PCL fibers. The microstructure of the PCL membranes was influenced by the bioglass production method. Both bioglasses seem to be promising biomaterials to improve bone tissue regeneration when incorporated into PCL.

Systemic and local effects of radiotherapy: an experimental study on implants placed in rats.

OBJECTIVES: Evaluate the modulating effect of ionizing radiation, blood cytokine levels, and bone remodeling of the interface around the implant to understand the radiation mechanisms which can impair the implants receptor site. MATERIAL AND METHODS: Sixty rats were submitted to grade V titanium implants in the femurs and were divided into the following groups: no-irradiation (N-Ir): control group with implant only; early-irradiation (E-Ir): implant + irradiation after 24 h; late-irradiation (L-Ir): implant + irradiation after 4 weeks; and previous-irradiation (P-Ir): irradiation + implant after 4 weeks. The animals in the E-Ir, L-Ir, and P-Ir groups were irradiated in two fractional stages of 15 Gy. At 3 days, 2 weeks, and 7 weeks after the final procedure, five animals were randomly euthanized per group. Serum levels of TNF-ɑ, IL-1ß, TGF-ß, IL-6, M-CSF, and IL-10 were measured from blood collected prior to euthanasia using the ELISA test. The pieces containing the implants were subjected to immunohistochemical labeling using the tartrate acid resistant to phosphatase, osteocalcin, and caspase-3 markers and mCT. The ANOVA test was used for statistical analysis, and the Tukey multiple comparison test (p < 0.05) was applied. RESULTS: The results indicated that ionizing radiation modifies the production of pro- and anti-inflammatory serum cytokines, the expression of proteins involved in bone remodeling and cellular apoptosis, as well as changes in bone formation. CONCLUSIONS: The results suggests that a longer period between radiotherapy and implant placement surgery when irradiation occurs prior to implant installation would allow the recovery and renewal of bone cells and avoid future failures in osseointegration. CLINICAL RELEVANCE: The search for modifications caused by ionizing irradiation in bone tissue can indicate the ideal period for implant placement without affecting the osseointegration process.