Sobrevivência em fadiga de coroas bioinspiradas bilaminadas: estudo in vitro / Fatigue survival rate of bioinspired bilaminar crowns: in vitro study

O objetivo deste estudo foi avaliar o comportamento biomecânico através da resistência à fadiga e análise por elementos finitos de coroas bioinspiradas bilaminadas com infraestruturas modificadas na superfície vestibular (Estudo A) e utilizando diferentes materiais cerâmicos com módulos elásticos distintos (Estudo B). Para isso, foram confeccionados 90 preparos para coroa total em resina epóxi G10, sobre os quais foram preparadas coroas bioinspiradas de acordo com os seguintes grupos: Estudo A - IC (infraestrutura convencional), IME (infraestrutura modificada estratificada) e IMC (infraestrutura modificada cimentada), todas confeccionadas em dissilicato de lítio (infraestrutura) + porcelana (recobrimento); Estudo B ­ DL+LEU (dissilicato de lítio + leucita), LEU+DL (leucita + dissilicato de lítio), CH+DL (cerâmica híbrida + dissilicato de lítio) e CH+LEU (cerâmica híbrida + leucita). Para o Estudo A, todas as infraestruturas foram usinadas; os recobrimentos dos grupos IC e IME foram confeccionados através da estratificação, e os recobrimentos do grupo IMC foram usinados. Já para o Estudo B, todas as peças foram usinadas, de acordo com o material cerâmico de cada grupo. Em seguida, foi realizada a cimentação adesiva dos recobrimentos sobre as infraestruturas (a depender do grupo) e das coroas sobre os preparos utilizando cimento resinoso fotopolimerizável (Variolink Esthetic LC). Após a cimentação, os espécimes foram submetidos ao teste de fadiga cíclica (10.000 ciclos, 20Hz), e como desfecho foram considerados dois eventos, em que o primeiro foi a ocorrência de trinca e/ou lascamento (evento 1) e o segundo foi a falha catastrófica do conjunto (evento 2). Os valores de carga e número de ciclos para falha em que foram observados os eventos 1 e 2 foram utilizados para realizar a análise de sobrevivência de acordo com Kaplan-Meier e Log-Rank (Mantel-Cox; 95%). As marcas de fratura e o modo de falha das coroas foram avaliados e classificados por estereomicroscópio óptico e microscópio eletrônico de varredura. Por fim, foi realizada análise por elementos finitos (FEA) para ambos os estudos, a fim de avaliar a distribuição de tensões sobre as coroas e interface adesiva. Para o Estudo A, os resultados do teste de fadiga mostraram que, considerando o evento 1 (trinca/lascamento), os grupos IC e IMC apresentaram médias de carga fadiga estatisticamente significantes entre si (733,33 N e 913,33 N, respectivamente), enquanto o grupo IME apresentou média superior (1.020 N). O mesmo foi observado para o número de ciclos em fadiga para todos os grupos. Ao considerar o evento 2 (falha catastrófica), os três grupos apresentaram médias estatisticamente semelhantes entre si (~1.028 N). Os resultados de FEA mostraram que o grupo IC concentrou maior tensão de tração do que os grupos IME e IMC. Para o Estudo B, no teste de fadiga, o grupo DL+LEU apresentou a maior média de resistência à fadiga (evento 1: 913,33 N e evento 2: 1033,33 N), enquanto todas as outras combinações de materiais cerâmicos analisadas foram estatisticamente semelhantes entre si, considerando carga e número de ciclos. Com relação ao FEA, os grupos com cerâmica híbrida (CH+DL e CH+LEU) apresentaram menores picos de concentração de tensão na infraestrutura do que os grupos com cerâmicas vítreas (DL+LEU e LEU+DL), porém, em contrapartida, concentraram maior tensão na interface adesiva. Com isso, conclui-se que a utilização da infraestrutura modificada é uma alternativa viável e promissora para tratamentos reabilitadores, apresentando sobrevivência em fadiga e distribuição de tensões satisfatórias. Além disso, a combinação entre uma infraestrutura de dissilicato de lítio e recobrimento de cerâmica a base de leucita corresponde a melhor abordagem considerando a infraestrutura modificada.(AU)

The objective of this study was to evaluate the biomechanical behavior through fatigue resistance and finite element analysis of bilaminar bioinspired crowns with modified infrastructures on the buccal surface (Study A) and using different ceramic materials with different elastic moduli (Study B). For this, 90 preparations were made for a full crown in G10 epoxy resin, on which bioinspired crowns were prepared according to the following groups: Study A - CI (conventional infrastructure), SMI (stratified modified infrastructure) and CMI (cemented modified infrastructure ), all made of lithium disilicate (infrastructure) + porcelain (veneer); Study B ­ LD+LEU (lithium disilicate + leucite), LEU+LD (leucite + lithium disilicate), HC+LD (hybrid ceramic + lithium disilicate) and HC+LEU (hybrid ceramic + leucite). For Study A, all infrastructures were machined; the coverings of the CI and SMI groups were made through stratification technique, and the veneers of the SMI group were machined. For Study B, all pieces were machined, according to the ceramic material of each group. Then, the veneers were cemented into their infrastructures (depending on the group) and crowns were cemented into preparations using light-cured resin cement (Variolink Esthetic LC). After cementing, the specimens were subjected to the cyclic fatigue test (10,000 cycles, 20Hz), and as an outcome two events were considered: the occurrence of cracking and/or chipping (event 1) and catastrophic failure (event 2). The load (N) and number of cycles to failure in which events 1 and 2 were observed were used to perform the survival analysis according to Kaplan-Meier and Log-Rank (Mantel- Cox; 95%). The fracture marks and failure mode of the crowns were evaluated and classified by optical stereomicroscope and scanning electron microscope. Finally, finite element analysis (FEA) was performed for both studies in order to evaluate the stress distribution over the crowns and adhesive interface. For Study A, the results of the fatigue test showed that, considering event 1 (cracking/chipping), the CI and CMI groups presented average to failure that were statistically significant compared to each other (733.33 N and 913.33 N, respectively), while the SMI group showed higher averages (1,020 N). Same pattern was observed for the number of cycles under fatigue for both groups. When considering event 2 (catastrophic failure), the three groups presented statistically similar means (~1,028 N). The FEA results showed that the CI group concentrated greater tensile stress than the CMI and SMI groups. For Study B, in the fatigue test, the LC+LEU group presented the highest average fatigue resistance (event 1: 913.33 N and event 2: 1033.33 N), while all other combinations of ceramic materials analyzed were statistically similar to each other, considering load and number of cycles. Regarding FEA, the groups with hybrid ceramics (HC+LC and HC+LEU) showed lower stress concentration peaks in the infrastructure than the groups with glass ceramics (LC+LEU and LEU+LC), however, on the other hand, concentrated greater tension at the adhesive interface. With this, it is concluded that the use of modified infrastructure is a viable and promising alternative for oral rehabilitation treatments, presenting satisfactory fatigue survival and adequate stress distribution. Furthermore, the combination of a lithium disilicate infrastructure and a leucite-based ceramic coating corresponds to the best approach considering the modified infrastructure.(AU)

Biomimetics and the restoration of the endodontically treated tooth / Biomimética e a restauração do dente tratado endodonticamente

Although much progress has been obtained in terms of the Endodontic treatment, the literature shows that true success can be only achieved with adequate coronal seal to avoid bacterial contamination, and protect the tooth structure from fracture. There are many options available to the clinician to restore the endodontically treated tooth; however, there is not much evidence available on what alternative is better than another. This review will critically present the current knowledge on restorative choices, including posts and endocrowns, showing advantages and disadvantages of different treatment forms. With this knowledge, we will also introduce the concept of biomimetics to endodontically treated teeth, and how the nature of their remaining tooth structure can benefit from this approach. This concept entails the use of mechanisms and biologically produced materials to restore a tooth in a way that would mimic its natural structure, with the purpose of achieving better long-term prognosis (AU)

Embora tenha se obtido progresso em relação ao tratamento endodôntico, a literatura mostra que o sucesso real só pode ser atingido com o selamento coronal adequado, para evitar-se a contaminação bacteriana e proteger-se a estrutura dental de fraturas. Há muitas opções disponíveis para o clínico para a restauração do dente tratado endodonticamente; entretanto, não há muita evidência disponível sobre qual alternativa é melhor que a outra. Esta revisão apresentará criticamente o conhecimento atual sobre opções restauradoras, incluindo retentores intraradiculares e endocrowns, mostrando vantagens e desvantagens das diferentes formas de tratamento. Com esse conhecimento, também introduziremos o conceito de biomimética, uma vez que dentes tratados endodonticamente, devido a natureza de sua estrutura dental remanescente, podem se beneficiar desta abordagem. Esse conceito envolve o uso de mecanismos e materiais produzidos biologicamente para restaurar um dente de forma a imitar a estrutura natural, com o objetivo de alcançar melhor prognóstico de longo-prazo.(AU)

The Influence of the Shoe over the Medial Foot Arch and the Lower Limbs Kinematics in Toddlers / A influência de calçados no arco longitudinal medial do pé e na cinemática dos membros inferiores de crianças no início da fase de aquisição de marcha

Abstract Objective To evaluate the biomechanical behavior of the medial longitudinal arch (MLA) of the foot and the kinematic parameters of the lower limbs with biomimetic footwear (BF) and non-biomimetic (NB1, NB2, NB3 and NB4) footwear in children at the beginning of the gait acquisition phase. Methods Four toddlers were evaluated at the beginning of the gait acquisition phase under the following conditions: walking barefoot, ambulation with BF and NB1, NB2, NB3 and NB4 footwear in hard floor. BF is described as biomimetic because of its property of emulating natural and irregular floors through a dynamic internal insole. The MLA and kinematics of the hip, knee, and ankle during gait were evaluated by three-dimensional motion analysis system. The similarity between the kinematic curves of barefoot and footwear conditions was analyzed by root mean square error (RMSE). Results The use of BF presented the highest magnitude of MLA and the greatest difference in relation to barefoot condition (higher RMSE). The BF showed less difference in the kinematics of the knee and ankle joints during gait when compared to barefoot condition (lower RMSE). NB2 footwear presented hip kinematics more similar to barefoot condition (lower RMSE). Conclusion Biomimetics footwear and NB2 shoes (both with wider forefoot region) generated smaller differences in lower limbs compared to barefoot. In addition, the MLA was higher in the BF, probably because different design from other shoes.

Resumo Objetivo Avaliar o comportamento do arco longitudinal medial do pé (ALM) e os parâmetros cinemáticos dos membros inferiores durante a deambulação com calçados biomiméticos (CBs) e não biomiméticos (NB1, NB2, NB3 e NB4) em crianças no início da fase de aquisição da marcha. Métodos Foram avaliadas quatro crianças no início da fase de aquisição da marcha nas seguintes condições: andar descalço, andar com CBs e calçados NB1, NB2, NB3 e NB4 em solo plano. O calçado biomimético é descrito como biomimético por emular pisos naturais e irregulares por meio de uma palmilha interna dinâmica. O ALM e a cinemática do quadril, joelho e tornozelo durante a marcha foram avaliados por meio de sistema de análise do movimento tridimensional. A similaridade entre as curvas cinemáticas das condições descalça e com calçado foi analisada por meio do cálculo de root mean square error (RMSE). Resultados O CB foi o que apresentou maior magnitude do ALM e maior diferença do ALM em relação à condição descalça (maior RMSE). O CB apresentou ainda menor diferença na cinemática das articulações do joelho e tornozelo durante a marcha quando comparado à condição descalça (menor RMSE). O calçado NB2 apresentou a cinemática do quadril mais semelhante à condição descalça (menor RMSE). Conclusão Os calçados CB e NB2 que apresentam a região do antepé mais larga geraram menores diferenças na cinemática dos membros inferiores. Além disso, o ALM foi maior no CB provavelmente devido a seu design ser diferente daquele dos demais calçados.

Nanomagnet-facilitated pharmaco-compatibility for cancer diagnostics:Underlying risks and the emergence of ultrasmall nanomagnets / 药物分析学报

Cancer therapy is a fast-emerging biomedical paradigm that elevates the diagnostic and therapeutic po-tential of a nanovector for identification,monitoring,targeting,and post-treatment response analysis.Nanovectors of superparamagnetic iron oxide nanoparticles(SPION)are of tremendous significance in cancer therapy because of their inherited high surface area,high reactivity,biocompatibility,superior contrast,and magnetic and photo-inducibility properties.In addition to a brief introduction,we summarize various progressive aspects of nanomagnets pertaining to their production with an emphasis on sustainable biomimetic approaches.Post-synthesis particulate and surface alterations in terms of pharmaco-affinity,liquid accessibility,and biocompatibility to facilitate cancer therapy are highlighted.SPION parameters including particle contrast,core-fusions,surface area,reactivity,photosensitivity,photodynamics,and photothermal properties,which facilitate diverse cancer diagnostics,are discussed.We also elaborate on the concept of magnetism to selectively focus chemotherapeutics on tumors,cell sorting,purification of bio-entities,and elimination of toxins.Finally,while addressing the toxicity of nanomaterials,the advent of ultrasmall nanomagnets as a healthier alternative with superior properties and compatible cellular in-teractions is reviewed.In summary,these discussions spotlight the versatility and integration of multi-tasking nanomagnets and ultrasmall nanomagnets for diverse cancer theragnostics.

Biomimetic Applications of Mimosa pudica L. in the Theoretical Development of a Pneumatic Actuator

Abstract For years, plants have tried to adapt to the environmental changes caused by time, improving and developing their biological structures. Many of these structural and functional properties of plants have great potential for the development of concepts in the field of biomimetics. Recent previous studies have shown that the movement of Mimosa pudica L. is caused by the variation of turgor pressure within the cells of organs motor, that is, the influx and efflux of water by osmosis, generating reversible changes in the shape of the plant. Thus, this article sought, through research and literature references, to carry out a survey of studies related to the seismonastic movements of the plant and its applications in the design of technological innovations. In addition, it presents the development of a pneumatic actuator based on the abstraction of the morphology of the primary pulvinus of the plant and the concept of bioinspired design of the theoretical model based on the technology of soft robots. As a result, the bioinspired actuator model of the plant movement is described. In addition, with a simulation, it was possible to observe that the flexible modules are capable of generating the proposed movement and allow movement of the actuator. With the study, it was possible to understand that the movement of the plant appears as an embryo for the projection of technologies, and that the proposed study appears as the basis for research with pneumatic actuators.

Restaurações Biológicas como Alternativa para Reabilitação de Dentes com Extensa Destruição Coronária / Biological Restoration as an Alternative to Rehabilitation of Extensively Compromised Teeth

Objetivo: Descrever reabilitações com coroas biológicas por meio de dois casos clínicos, um dente anterior e um posterior. Material e Método: O estudo apresenta dois casos clínicos em que reabilitações de dentes extensamente destruídos foram realizadas. Em um dos casos é apresentada a reabilitação do dente 14 e no seguinte uma reabilitação simultânea dos dentes 21 e 22. Em ambos os casos foram utilizados dentes humanos provenientes de um banco de dentes humanos (BDH). Para a seleção dos dentes, utilizou-se como parâmetros os diâmetros dos dentes a serem reabilitados, bem como as medidas do dente homólogo contralateral. Os dentes obtidos junto a BDH foram seccionados, a coroa biológica esvaziada e então reembasada com resina composta sobre um modelo de gesso obtido dos pacientes. Após o reembasamento e ajustes oclusais ainda no modelo de gesso, as coroas foram cimentadas com cimento resinoso. Resultados: Em ambos os casos clínicos, os pacientes foram reabilitados adequadamente, de forma rápida e com custo reduzido. Conclusão: Restaurações biológicas podem ser utilizadas para reabilitação de dentes permanentes anteriores e posteriores; além de estimular o correto descarte de futuros dentes extraídos, sendo esses destinados a bancos de dentes humanos.

Objective: To describe rehabilitations with biological crowns by two clinical cases, one anterior and one posterior. Methods: The study presents two clinical cases in which extensively damage teeth were rehabilitated. In one, the rehabilitation of tooth 14 is presented and, in the other, a simultaneous rehabilitation of teeth 21 and 22 was performed. In both cases, human teeth from a human tooth bank (HTB) were used. For teeth selection, the diameters of the teeth to be rehabilitated, as well as, the measurements of the contralateral homologous tooth were used as parameters. The teeth obtained with HTB were sectioned, the biological crown emptied and then relined with composite resin on cast obtained from the patients. After the reline and occlusal adjustments, the crowns were cemented with resin cement. Results: The patients were rehabilitated properly, quickly and with reduced cost. Conclusion: Biological restorations can be used for rehabilitation of anterior and posterior permanent teeth; besides to stimulate the correct discard of extracted teeth, being these destined to human teeth banks.

Biological Restorations: A foreseeable possibility in the junction between dentistry and technology / Restaurações Biológicas: Uma possibilidade previsível no encontro da Odontologia com a Tecnologia

Prosthetic rehabilitation can generate doubts among professionals regarding the type of material to choose when planning rehabilitation treatments. The establishment of reliable criteria for material selection raises frequent questions. This work presents a concept and an alternative and simplified proposal to paradigm shift in therapeutic approaches based on three trends in restorative dentistry: Biomimetics, the use of natural tissue as a restorative material, which offers potential for the recovery of the mechanical, aesthetic and biological properties of teeth; digital dentistry and CAD/CAM systems; and adhesive technology, which has undergone exponential and impressive advances. However, further studies are needed to evaluate the long-term performance of restorations in this variable field. (AU)

Muitas dúvidas surgem quanto ao tipo ideal de material restaurador a ser escolhido durante a elaboração do planejamento em tratamentos reabilitadores. Determinar critérios seguros para seleção do material são questionamentos frequentes. Este trabalho apresenta, por meio de um caso clínico, um conceito: restaurações biológicas e uma proposta alternativa e simplificada para quebrar paradigmas quanto a novas abordagens terapêuticas com as três tendências da Odontologia Restauradora Moderna: Biomimética ­ mimetizar e/ou utilizar o tecido natural dental como o material restaurador, com potencial de recuperar as propriedades mecânicas, estéticas e biológicas dos dentes danificados, a Odontologia digital e Sistemas CAD/CAM - com avanços exponenciais e a consagrada tecnologia adesiva. Porém mais estudos ainda são necessários para avaliar o desempenho a longo prazo dessas restaurações neste vasto campo de variabilidades. (AU)

Advances in biomimetic drug delivery systems based on platelet and platelet membrane / 中国药科大学学报

@#Platelet is an important component of human blood, which plays a key role in the physiological and pathological processes. Recently, novel drug delivery system based on platelet and platelet membrane bionics attracted much attention. Compared to the traditional drug carriers, platelet and platelet membrane-based biomimetic drug delivery system has great performances in biocompatibility, longer circulation and stronger ability of targeting. This review presented the features, classifications, drug-loading and applications of platelet and platelet membrane-based biomimetic drug delivery systems, promoting their development and application in the future.

Efecto de agentes blanqueadores libres de peróxido sobre el color dental. Revisión sistemática / Effect of Peroxide-Free Dental Bleaching Agents on Dental Color. Systematic Review

Antecedentes: Los agentes blanqueadores oxidantes tales como los peróxidos generan daños irreversibles en el esmalte dental y afectan químicamente el componente orgánico e inorgánico del esmalte. Se reportan en la literatura sustancias alternativas que pueden mejorar el color del esmalte, sin causarle daño. Objetivo: Identificar las sustancias blanqueadoras tipo remineralizante reportadas en la literatura y su efecto en el color del esmalte dental. Métodos: Se consultaron las bases de datos PubMed, ScienceDirect, Embase, Scielo, Lilacs y Scopus, las palabras clave empleadas para la búsqueda fueron dental enamel, tooth bleaching, bleaching, calcium phosphate, hidroxyapatite, apatite, biomimetic, biomimetics, conectadas por el operador booleano AND y OR de diferentes maneras. Los criterios de elegibilidad de los artículos que harían parte de la revisión fueron que no incluyeran peróxidos de hidrógeno y carbamida con adición fluoruros y fosfatos de calcio y adicionalmente que emplearan un método de medición de color. Resultados: El resultado de la búsqueda arrojó 7 artículos, las sustancias encontradas de tipo remineralizante fueron hidroxiapatita sintética, fosfatos de calcio y el hexametafosfato de sodio. Según los criterios de evaluación definidos solo 4 de ellos tuvieron un nivel de evidencia alto, uno nivel medio y dos bajos. Todos los estudios reportan con los tratamientos probados, la capacidad de generar cambios en el color del esmalte dental. Conclusión: Las sustancias blanqueadoras remineralizantes encontradas, tienen la capacidad de producir cambios en el color del esmalte dental, lo cual se evidencia con modificación en las diferentes escalas de medición empleadas.

Background: Oxidizing bleaching agents such as peroxides generate irreversible damage to dental enamel and chemically affect the organic and inorganic component of the enamel. Alternative substances that can improve the color of the enamel without damaging it are reported in the literature. Purpose: To identify the remineralizing bleaching substances reported in the literature and their effect on the color of the dental enamel. Methods: The databases PubMed, ScienceDirect, Embase, SciELO, Lilacs and Scopus were consulted, the keywords used for the search were dental enamel, tooth bleaching, bleaching, calcium phosphate, hydroxyapatite, apatite, biomimetic, biomimetics, connected by the Boolean operator AND and OR in different ways. The eligibility criteria of the articles that would be part of the review were not to include hydrogen peroxide and carbamide peroxides with addition of fluorides and calcium phosphates and additionally using a color measurement method. Results: The result of the search yielded 7 articles, the substances found of remineralizing type were synthetic hydroxyapatite, calcium phosphates and sodium hexametaphosphate. According to the evaluation criteria defined, only 4 of them had a high level of evidence, one medium level and two low. All studies report with proven treatments the ability to generate changes in tooth enamel color. Conclusions: The remineralizing whitening substances found have the ability to produce changes in the color of the dental enamel, which is evidenced with modification in the different measurement scales used.

Materiales bioactivos en la remineralización dentinaria / Bioactive materials in dentin remineralisation

El enfoque en el tratamiento de las lesiones cariosas que afectan el tejido dentinario se ha modificado de forma dramática en las últimas décadas. El conocimiento acerca de la etiología de la caries dental, la fisiopatología dentinaria y el desarrollo de biomateriales dentales y técnicas adhesivas, han confluido en tratamientos de mínima intervención.En virtud de esta nueva alternativa en el tratamiento de las lesiones dentinarias, es necesario evaluar la posible recuperación de la dentina mediante tratamientos remineralizantes y el desarrollo de materiales bioactivos que posibiliten la reparación o regeneración del tejido imitando los mecanismos fisiológicos de mineralización y recomponiendo las propiedades mecánicas originales del tejido, con el fin de obtener resultados clínicos exitosos basados en tratamientos con enfoque biomimético.

The focus of the treatment of carious lesions affecting dentin tissue has changed dramatically in recent decades. Knowledge about the etiology of dental caries, dentin pathophysiology and the development of dental biomaterials and adhesive techniques have resulted in minimal intervention treatments.Given this new alternative for treating dentin lesions, it is necessary to evaluate the potential recovery of dentin through mineralization treatments and the development of bioactive materials that facilitate the repair or regeneration of this tissue by imitating the physiological mechanisms of mineralization and recomposing the tissue´s original mechanical properties. This is done to obtain successful clinical results based on biomimetic treatments.

Clinical application of adhesive systems - a critical review: biomimetic approach / Revisão crítica da aplicação clínica dos sistemas adesivos: abordagem biomimética

The various functions and clinical applications of adhesive systems have become a fundamental part of restorative treatment. The biggest challenge for such systems is to provide adequate adhesion to the different tissues, which can be very diverse in nature. When choosing the appropriate adhesive system, the dentist should be familiar with the origin, composition, action mechanism and method of application of each system. The commercially available products and their high technical status have made it possible for the clinician to develop a philosophy of maximum tissue preservation, optimized esthetics, up-to-date concepts and procedures and full function of the restored element, compatible with biomimetic theory. The literature describes the superior qualities of results obtained with three-step total etching adhesives and the use of chlorhexidine as a factor to increase longevity. Future perspectives include the use of ethanol, inactivating agents of enzymes released in the adhesive process and the action of agents that act upon the dentin matrix.

As diversas funções e aplicabilidades clínicas dos sistemas adesivos os tornaram parte fundamental da terapêutica restauradora. O desafio maior destes sistemas está em prover qualificada adesão aos diferentes tecidos uma vez que estes são muito distintos em sua constituição. Para que essa escolha seja feita corretamente o dentista deve conhecer a origem, composição, mecanismo de ação e modo de aplicação de cada sistema. Os produtos disponíveis e o estado técnico, alcançados atualmente, tem possibilitado aos clínicos o desenvolvimento de uma filosofia de máxima conservação tecidual, estética otimizada, atualização de condutas e conceitos bem como função plena do elemento dental restaurado compatíveis com uma filosofia biomimética. A literatura vigente apresenta superioridade de resultados com adesivos de condicionamento total de três etapas, uso de clorexidina como fator de aumento da longevidade e perspectivas futuras que incluem trabalhos com o uso de etanol, agentes inativadores enzimas liberadas no processo adesivo e a ação de agentes que atuem na malha dentinária.

Nanotechnology Biomimetic Cartilage Regenerative Scaffolds

Cartilage has a limited regenerative capacity. Faced with the clinical challenge of reconstruction of cartilage defects, the field of cartilage engineering has evolved. This article reviews current concepts and strategies in cartilage engineering with an emphasis on the application of nanotechnology in the production of biomimetic cartilage regenerative scaffolds. The structural architecture and composition of the cartilage extracellular matrix and the evolution of tissue engineering concepts and scaffold technology over the last two decades are outlined. Current advances in biomimetic techniques to produce nanoscaled fibrous scaffolds, together with innovative methods to improve scaffold biofunctionality with bioactive cues are highlighted. To date, the majority of research into cartilage regeneration has been focused on articular cartilage due to the high prevalence of large joint osteoarthritis in an increasingly aging population. Nevertheless, the principles and advances are applicable to cartilage engineering for plastic and reconstructive surgery.

Latent Transforming Growth Factor-beta1 Functionalised Electrospun Scaffolds Promote Human Cartilage Differentiation: Towards an Engineered Cartilage Construct

BACKGROUND: To overcome the potential drawbacks of a short half-life and dose-related adverse effects of using active transforming growth factor-beta 1 for cartilage engineering, a cell-mediated latent growth factor activation strategy was developed incorporating latent transforming growth factor-beta1 (LTGF) into an electrospun poly(L-lactide) scaffold. METHODS: The electrospun scaffold was surface modified with NH3 plasma and biofunctionalised with LTGF to produce both random and orientated biofunctionalised electrospun scaffolds. Scaffold surface chemical analysis and growth factor bioavailability assays were performed. In vitro biocompatibility and human nasal chondrocyte gene expression with these biofunctionalised electrospun scaffold templates were assessed. In vivo chondrogenic activity and chondrocyte gene expression were evaluated in athymic rats. RESULTS: Chemical analysis demonstrated that LTGF anchored to the scaffolds was available for enzymatic, chemical and cell activation. The biofunctionalised scaffolds were non-toxic. Gene expression suggested chondrocyte re-differentiation after 14 days in culture. By 6 weeks, the implanted biofunctionalised scaffolds had induced highly passaged chondrocytes to re-express Col2A1 and produce type II collagen. CONCLUSIONS: We have demonstrated a proof of concept for cell-mediated activation of anchored growth factors using a novel biofunctionalised scaffold in cartilage engineering. This presents a platform for development of protein delivery systems and for tissue engineering.

O design inteligente e a estratificação biomimética em restaurações diretas posteriores: consolidando a era pós-amálgama / Rational design and biomimetic layering of posterior composite restorations: consolidating the postamalgam era

No campo da dentística restauradora, muitas conquistas têm sido alcançadas, principalmente em relação à crescente conscientização dos pacientes quanto à possibilidade de se obterem restaurações mais funcionais e estéticas. O grande dilema tem sido como raciocinar clinicamente com esses novos conceitos, ou seja, modificar a abordagem antiga, que era baseada na ausência da verdadeira união. Quais conceitos clássicos devem permanecer vigentes nesse novo contexto? Mimetizar, em ciência, envolve permitir a cópia de um modelo que, na área odontológica, sem dúvida, é o dente intacto. Este artigo aborda a associação desse conceito com a técnica e a seleção dos materiais na prática clínica.

The increased awareness of patients for more functional and esthetic restorations led to a number of archievements that occurred in Restorative Dentistry. A major concern is how to clinically thinking on these new concepts, changing the old approach which was based on the lack of true adhesion. Which classical concepts should be maintained in this new context? Mimicking in science, involves a process of copying a model that, in the dental field, is in most cased an intact tooth. This article discusses the association of this concept with the technique and selection of materials in clinical practice.

Recent developments in mechanics of biological materials: A brief review / 医用生物力学

As a rapidly developing area in biomechanics, mechanics of biological materials aims to investigate the fundamental relationship between functions, properties, structures, and compositions of various natural biological materials at different length scales and the underlying physical mechanisms through experimental research and theoretical analysis, and to provide inspirations from the splendid living world for the biomimetic design of new materials. In this paper, some recent achievements, mainly made by Chinese scholars in this field, are briefly reviewed, including the stiffening and toughening mechanisms of such biological composites as nacres and horns, the relation between the surface wetting behavior and the micro/nanostructures, and some relevant biomimetic applications as well. The contents of seven invited papers published in this special issue are also introduced.