Numerical-experimental procedure for predicting fatigue life in SAE AMS 7475-T7351 aluminum alloy considering the effect of stress ratio.

This study addresses the prediction of fatigue life in SAE AMS 7475-T7351 aluminum alloys under variable loads, commonly used in the construction of aircraft fuselages. The main objective of the research was to develop a numerical-experimental procedure to analyze crack growth, using the Walker's approach which considers the effects of the stress ratio R on the fatigue crack growth rate d a / d N , combined with the Finite Element Method and Linear Regression of the Stress Intensity Factor. Observations showed that Walker's model effectively consolidated fatigue crack propagation data for various stress ratios when applied longitudinally to L-T rolling orientation, due to low dependence of exponent m on R -value in d a / d N equation. Simple averaging of m values effectively calculated Walker's exponent. The methodology employed experimental tests following ASTM standards for tension, fracture toughness, and fatigue, complemented by Finite Element Method (FEM) simulations. The Walker's model proved more effective, while the Paris-Erdogan model, which ignores the R effect, resulted in overly conservative service life estimates. The principle of similitude suggests that this methodology could be effective in predicting fatigue life in cases with complex geometries, where calculating the Stress Intensity Factor Fracture parameter is challenging and the Finite Element Method shows efficiency.

Examining the Physicochemical Composition of Three Bioceramic Putties for Endodontic Use.

OBJECTIVE: This study aimed to address the lack of comparative analyses of newly developed bioceramic materials by examining the chemical composition, thermodynamic profile, and microscopic surface features of three bioceramic putties: EndoSequence BC Root Repair Material Fast Set Putty (ESRRM-FS), BIO-C Repair (BCR), and Cera Putty (CP). METHODS: Samples of each of the three bioceramic putty obtained directly from manufacturers were prepared for analysis of physicochemical composition and microscopic features by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) imagery, and energy-disper-sive X-ray spectroscopy (EDS). The data obtained was qualitatively and statistically analysed. Statistical signif-icance was determined at p≤0.05. RESULTS: DSC analysis indicated a standard polymeric vehicle for BCR and CP, coinciding with the polyethene glycol (PEG) thermal profile; the polymeric vehicle in ESRRM-FS remains to be identified. The material with the highest heat capacity was CP (p<0.05), followed by ESRRM-FS and BCR. TGA revealed an inflexion point at 394.12 ºC for ESRRM-FS, which may correspond to the mass loss of dihydroxylation of calcium hydroxide. A more homogenous structure was observed in scanning electron microscopy (SEM) images for ESRRM-FS. EDS analysis indicated BCR had minimal amounts of aluminium (2.06+-0.44%) and a lower percentage of cal-cium than ESRRM-FS (9.11+-1.38% vs. 11.3+-0.87%). CP was composed of aluminium (49.35+-7.01%), carbon (30.65+-5.62%), and oxygen (16.75+-2.44%); no silicon was identified. ESRRM-FS had no aluminium present and the highest calcium percentage (11.3+-0.87%) (p<0.05). CONCLUSION: BCR is a Portland cement-derived material with a lower percentage of calcium than ESRRM-FS and minimal amounts of aluminium. CP is a monocalcium aluminate cement, mainly composed of aluminium, carbon, and oxygen. ESRRM-FS is a biphasic material with the highest calcium percentage among all materials studied and no aluminium.

Forecasting the rheological state properties of self-compacting concrete mixes using the response surface methodology technique for sustainable structural concreting.

It is structurally pertinent to understudy the important roles the self-compacting concrete (SCC) yield stress and plastic viscosity play in maintaining the rheological state of the concrete to flow. It is also important to understand that different concrete mixes with varying proportions of fine to coarse aggregate ratio and their nominal sizes produce different and corresponding flow- and fill-abilities, which are functions of the yield stress/plastic viscosity state conditions of the studied concrete. These factors have necessitated the development of regression models, which propose optimal rheological state behavior of SCC to ensure a more sustainable concreting. In this research paper on forecasting the rheological state properties of self-compacting concrete (SCC) mixes by using the response surface methodology (RSM) technique, the influence of nominal sizes of the coarse aggregate has been studied in the concrete mixes, which produced experimental mix entries. A total of eighty-four (84) concrete mixes were collected, sorted and split into training and validation sets to model the plastic viscosity and the yield stress of the SCC. In the field applications, the influence of the sampling sizes on the rheological properties of the concrete cannot be overstretched due to the importance of flow consistency in SCC in order to achieve effective workability. The RSM is a symbolic regression analysis which has proven to exercise the capacity to propose highly performable engineering relationships. At the end of the model exercise, it was found that the RSM proposed a closed-form parametric relationship between the outputs (plastic viscosity and yield stress) and the studied independent variables (the concrete components). This expression can be applied in the design and production of SCC with performance accuracies of above 95% and 90%, respectively. Also, the RSM produced graphical prediction of the plastic viscosity and yield stress at the optimized state conditions with respect to the measured variables, which could be useful in monitoring the performance of the concrete in practice and its overtime assessment. Generally, the production of SCC for field applications are justified by the components in this study and experimental entries beyond which the parametric relations and their accuracies are to be reverified.

Influencia del termociclado sobre la estabilidad del color de dos resinas compuestas / Influence of thermocycling on the color stability of two composite resins

Objetivo: Cuando las resinas compuestas son expuestas a procesos de envejecimiento naturales en boca, como es el ciclaje térmico, pueden sufrir un deterioro en sus propiedades ópticas. El objetivo de este estudio fue evaluar la influencia del envejecimiento térmico sobre la estabilidad del color de dos resinas compuestas. Materiales y métodos: Se confeccionaron 120 pas- tillas de resinas compuestas, divididas en dos grupos: uno de resina Spectra Smart (n=60) y otro de resina Filtex Z350 XT (n=60). Estas muestras fueron sometidas a distintos regíme- nes de ciclaje térmico de 0, 10.000, 20.000 y 30.000 ciclos con temperaturas de entre 5 ºC +/- 2 ºC y 55 ºC +/- 2 °C. Los parámetros de color CIE L*a*b* de cada muestra se mi- dieron con un espectrofotómetro antes y después del proceso de envejecimiento. Las diferencias de color se calcularon me- diante la fórmula CIELAB (ΔE). Los datos fueron analizados estadísticamente usando la prueba no paramétrica de Kruskal Wallis y de U-Mann Whitney. Resultados: Los distintos regímenes de termociclado produjeron cambios de color estadísticamente significativos en ambos materiales. El material que tuvo menor estabilidad cromática fue Spectra Smart aunque sin diferencias estadísti- camente significativas. Conclusión: El envejecimiento térmico simulado a tres años afecta la estabilidad de color de las muestras, tanto de las resinas Spectra Smart, como de Filtex Z350 XT, sin alcanzar los valores que clínicamente determinarían la necesidad del reemplazo de las restauraciones (AU)

Aim: When composite resins are exposed to natural ag- ing processes in the mouth, such as the thermal cycling, they may suffer a deterioration in their optical properties. The aim of this study was to evaluate the influence of thermal aging on the color stability of two composite resins. Materials and methods: 120 composite resins tablets were made, divided into two groups: one of Spectra Smart res- in (n=60) and another of Filtex Z350 XT resin (n=60). These were subjected to different thermal cycle regimes of 0, 10,000, 20,000 and 30,000 cycles with temperature between 5 °C +/- 2 °C and 60 °C +/- 2 °C. The CIE L*a*b* color parameters of each sample were measured with a spectrophotometer before and after the aging process. Color differences were calculat- ed using the CIELAB formula (ΔE). The data were statisti- cally analyzed using the non-parametric Kruskal Wallis and U-Mann Whitney tests. Results: The different thermocycling regimes produce statistically significant color changes in both materials. The material that had the least chromatic stability was Spectra Smart, although without statistically significant differences. Conclusion: Simulated 3 year thermal aging affects the color stability of the samples, both Spectra Smart resins and Filtex Z350 XT, without reaching the values that would clini- cally determine the need to replace the restorations (AU)

Avaliação do potencial de regeneração óssea guiada e biocompatibilidade de membrana polimétrica nano estruturada à base de quitosana / Evaluation of guided bone regeneration potential and biocompatibility of nano-structured polymeric membrane based on chitosan

A regeneração óssea guiada (ROG) é uma técnica muito utilizada na odontologia para reconstrução de defeitos alveolares para posterior instalação de implantes dentários. Para que a técnica seja efetiva, uma membrana que permita o isolamento de diferentes tipos teciduais é necessária. A quitosana nanoestruturada modificada por hidróxidos duplos lamelares (HDL) é um biopolímero sintético que busca unir as características promissoras da quitosana como material bioadesivo e com propriedades antimicrobianas com a hidrocalcita buscando aprimorar suas características estruturais. O objetivo deste estudo in vivo foi avaliar a biocompatibilidade e o potencial de regeneração óssea guiada de uma nova membrana produzida à base de quitosana nanoestrutada modificada por HDL. Ratos Wistar machos adultos (n=64) foram divididos randomicamente em 2 grupos de acordo com o tratamento: Colágeno (COL) e Quitosana (QTS). Os animais foram submetidos à cirurgia para instalação de uma membrana no subcutâneo da região dorsal e à realização de 2 defeitos críticos na calota craniana, respeitando cada lado do animal. O defeito do lado direito foi coberto por uma das membranas testadas (COL ou QTS) enquanto o outro permanecia descoberto (Controle). Oito animais de cada grupo foram sacrificados em 4 tempos de acompanhamento: 3, 7, 14 e 30 dias. Amostras de calota e subcutâneo foram coletadas e preservadas em paraformaldeído 4%. As amostras de calota foram escaneadas em viii microtomógrafico para análise da quantidade de osso neoformado. Em seguida, os espécimes de calota e subcutâneo foram processados laboratorialmente para exames histológicos em parafina: para avaliação histomorfológica das características do processo cicatricial e de degradação das membranas e histomorfométrica para quantificação do processo inflamatório e do nível de reação tecidual por meio do escore global de reação tecidual (EGRT). Análises descritivas e inferenciais foram realizadas para comparação entre os grupos com nível de significância de 5%. Os resultados não demonstraram diferenças entre os grupos COL e QTS quanto à intensidade do processo inflamatório e EGRT. Já em relação aos defeitos na calota, o grupo QTS apresentou maior neoformação óssea em relação ao grupo controle aos 30 dias (p=0,04). Com base nos resultados conclui-se que as membranas de quitosana nano particuladas modificadas por HDL apresentaram biocompatibilidade compatível com a membrana de colágeno e efetividade para uso como barreira em ROG. (AU)

Guided bone regeneration (GBR) is a technique widely used in dentistry to reconstruct alveolar defects for subsequent installation of dental implants. For the technique to be effective, a membrane that allows the isolation of different tissue types is necessary. Nanostructured chitosan modified by lamellar double hydroxides (HDL) is a synthetic biopolymer that seeks to combine the promising characteristics of chitosan as a bioadhesive material with antimicrobial properties with hydrocalcite seeking to improve its structural characteristics. The objective of this in vivo study was to evaluate the biocompatibility and guided bone regeneration potential of a new membrane produced based on nanostructured chitosan modified by HDL. Adult male Wistar rats (n=64) were randomly divided into 2 groups according to treatment: Collagen (COL) and Chitosan (QTS). The animals underwent surgery to install a membrane in the subcutaneous tissue of the dorsal region and to perform 2 critical defects in the cranial vault, respecting each side of the animal. The defect on the right side was covered by one of the tested membranes (COL or QTS) while the other remained uncovered (Control). Eight animals from each group were sacrificed at 4 follow-up times: 3, 7, 14 and 30 days. Calvary and subcutaneous samples were collected and preserved in 4% paraformaldehyde. The cap samples were scanned in a microtomograph to analyze the amount of newly formed bone. Then, the cap and subcutaneous specimens were processed in the laboratory for histological examinations in paraffin: for histomorphological evaluation of the characteristics of the scarring process and membrane degradation and histomorphometric for quantification of the inflammatory process and the level of tissue reaction through the global score of tissue reaction (EGRT). Descriptive and inferential analyzes were performed for comparison between groups with a significance level of 5%. The results showed no differences between the COL and QTS groups regarding the intensity of the inflammatory process and EGRT. In relation to the defects in the calvaria, x the QTS group presented greater new bone formation in relation to the control group at 30 days (p=0.04). Based on the results, it is concluded that the nanoparticulate chitosan membranes modified by HDL showed biocompatibility compatible with the collagen membrane and effectiveness for use as a barrier in GBR. (AU)

Effect of frozen storage on preservation of a silicone-based test food material

Aim: This study aimed to evaluate the effect of frozen storage on the physical properties of a silicone-based test food material, highly used to evaluate the masticatory performance in research settings. Methods: A total of 1,666 silicone cubes of Optosil Comfort® with 5.6-mm edges were shaped and stored at -18°C. The cubes were subsequently tested for flexural strength (maximum force, displacement, stress, and strain) before breaking (n = 136), changes in weight and size (n = 170), and masticatory performance (n = 1360) at eight timepoints: immediately after cube preparation (baseline, no freezing), and 1, 2, 3 and 4 weeks, and 2, 4 and 6 months after frozen storage. The cubes were thawed 8 h before each assessment. Results: The maximum force, stress, maximum displacement, and deformation values for the cubes were not affected by freezing (P > 0.05). At all of the time points, the cubes exhibited similar weight (P = 0.366) and size (identical values). The masticatory performance for the cubes also showed no differences from baseline through 6 months (P = 0.061). Conclusion: Freezing Optosil Comfort® silicone cubes did not alter the physical and mechanical properties of the material, being suitable to optimize the assessment of masticatory parameters for research purposes

A Brief Review on the High-Energy Electromagnetic Radiation-Shielding Materials Based on Polymer Nanocomposites.

This paper revises the use of polymer nanocomposites to attenuate high-energy electromagnetic radiation (HE-EMR), such as gamma radiation. As known, high-energy radiation produces drastic damage not only in facilities or electronic devices but also to life and the environment. Among the different approaches to attenuate the HE-EMR, we consider the use of compounds with a high atomic number (Z), such as lead, but as known, lead is toxic. Therefore, different works have considered low-toxicity post-transitional metal-based compounds, such as bismuth. Additionally, nanosized particles have shown higher performance to attenuate HE-EMR than those that are micro-sized. On the other hand, materials with π-conjugated systems can also play a role in spreading the energy of electrons ejected as a consequence of the interaction of HE-EMR with matter, preventing the ionization and bond scission of polymers. The different effects produced by the interactions of the matter with HE-EMR are revised. The increase of the shielding properties of lightweight, flexible, and versatile materials such as polymer-based materials can be a contribution for developing technologies to obtain more efficient materials for preventing the damage produced for the HE-EMR in different industries where it is found.

Avaliação por câmera termográfica de implante de co-poliamida associado a elastômero termoplástico em traqueia de coelho / Evaluation of co-polyamide implant comprising a thermoplastic elastomer in rabbit trachea using thermographic camera / Evaluación con cámara termográfica de un implante de copoliamida asociado a un elastómero termoplástico en la tráquea de un conejo

La termografía es eficaz para detectar la temperatura de la superficie corporal y puede utilizarse como método auxiliar para diagnosticar procesos inflamatorios y para evaluar patrones de cicatrización, lo que permite su amplio uso en Medicina Veterinaria. El procedimiento ha ganado protagonismo por ser una técnica no invasiva, indolora, de bajo costo y segura, ya que elimina la necesidad del uso de contrastes, sedación y radiación. El objetivo de este artículo es analizar la eficacia del uso de la termografía en la evaluación de la biocompatibilidad en la reparación del tejido traqueal, así como identificar procesos inflamatorios tras la implantación de la prótesis impresa en nailon con impresión 3D asociada al elastómero termoplástico - PCTPE. Se dividieron quince conejos blancos de Nueva Zelanda (Oryctolagus cuniculus) machos en tres grupos de diferentes períodos de evaluación (siete, 15 y 30 días). Se implantaron prótesis tridimensionales tras la resección completa de tres anillos traqueales. La evaluación de las imágenes termográficas se realizó en el lugar de implantación de la prótesis traqueal justo antes del procedimiento quirúrgico e inmediatamente antes de la eutanasia. Hubo una diferencia significativa entre los grupos, ya los 30 días la temperatura mínima (p = 0,0357), media (p = 0,0135) y máxima (p = 0,0058) fue menor en comparación con los otros grupos...(AU)

Thermography is efficient for detecting body surface temperature and can be used as an auxiliary method for the diagnosis of inflammatory processes and in the evaluation of scarring patterns, which allows its wide use in Veterinary Medicine. The procedure has gained prominence, as it is a non-invasive, painless, low-cost and safe technique, since it does not require the use of contrasts, sedation and radiation. The objective of this article is to analyze the efficiency of the use of thermography in the evaluation of biocompatibility in tracheal tissue repair, as well as to identify inflammatory processes after implantation of the 3D printed impression prosthesis of nylon associated with the thermoplastic elastomer - PCTPE. Fifteen male New Zealand White rabbits (Oryctolagus cuniculus) were divided into three groups of different evaluation periods (seven, 15 and 30 days). Three-dimensional prostheses were implanted after complete resection of three tracheal rings. The evaluation of the thermographic images was performed at the place of implantation of the tracheal prosthesis just before the surgical procedure and immediately before euthanasia. There was a significant difference between the groups, and at 30 days the minimum (p = 0,0357), average (p = 0,0135) and maximum (p = 0,0058) temperature was lower when compared with the other groups...(AU)

A termografia é eficiente para detecção da temperatura da superfície corporal e pode ser utilizada como método auxiliar de diagnóstico de processos inflamatórios e na avaliação de padrões cicatriciais, o que permite sua ampla utilização na Medicina Veterinária. O procedimento tem ganhado destaque, pois trata-se de técnica não invasiva, indolor, de baixo custo e segura, pois dispensa a necessidade do uso de contrastes, sedação e radiação.  O objetivo desse artigo é analisar a eficiência do uso da termografia na avaliação da biocompatibilidade em reparação tecidual traqueal, bem como identificar processos inflamatórios após a implantação da prótese impressa em impressão 3D de náilon associado ao elastômero termoplástico- PCTPE. Quinze coelhos machos, da linhagem Nova Zelândia Branco (Oryctolagus cuniculus), foram distribuídos em três grupos de períodos de avaliação diferentes (sete, 15 e 30 dias). As próteses tridimensionais foram implantadas após ressecção completa de três anéis traqueais. A avaliação das imagens termográficas foi efetuada no local de implantação da prótese traqueal no momento anterior ao procedimento cirúrgico e imediatamente antes da eutanásia. Houve diferença significativa entre os grupos, sendo que aos 30 dias a temperatura mínima (p=0,0357), média (p=0,0135) e máxima (p=0,0058) foi menor quando comparado com os demais grupos...(AU)

Use of auxiliary devices during retreatment of direct resin composite veneers.

The removal of direct composite veneers, when the retreatment is necessary, represents a challenge to the clinician, since the healthy dental structure must be preserved. Thus, the aim of this study was to compare the accuracy provided by different auxiliary devices during retreatment of direct composite veneers. Seventy-five bovine teeth were prepared for direct composite veneers, scanned (T1), and restored. Specimens were divided into 5 groups for retreatment: conventional high-speed handpiece without auxiliary device (WD); high-speed handpiece with a white LED (WL); high-speed handpiece with an UV light (UL); electric motor and multiplier 1/5 handpiece (EM); and conventional high-speed handpiece using magnifying loupe (ML). After retreatments, other scanning was performed (T2). Changes on dental wear or composite residues areas, as well as, the average between wear and presence of residues were measured. Data were submitted to Kruskal-Wallis and Dunn's post-test (p≤ 0.05). There were greater areas of wear for ML, being statistically superior to WD and EM groups. The ML presented smaller residues areas, being statistically lower than the WD and EM groups. Regarding the average between wear and the presence of resin residues, additional wear occurred after re-preparation, regardless of the group. Magnifying loupe promoted greater areas of wear and smaller areas of resin residues than conventional high-speed handpiece and electric motor. Both techniques using light accessories did not differ from other ones.

Avaliação por câmera termográfica de implante de co-poliamida associado a elastômero termoplástico em traqueia de coelho / Evaluation of co-polyamide implant comprising a thermoplastic elastomer in rabbit trachea using thermographic camera / Evaluación con cámara termográfica de un implante de copoliamida asociado a un elastómero termoplástico en la tráquea de un conejo

La termografía es eficaz para detectar la temperatura de la superficie corporal y puede utilizarse como método auxiliar para diagnosticar procesos inflamatorios y para evaluar patrones de cicatrización, lo que permite su amplio uso en Medicina Veterinaria. El procedimiento ha ganado protagonismo por ser una técnica no invasiva, indolora, de bajo costo y segura, ya que elimina la necesidad del uso de contrastes, sedación y radiación. El objetivo de este artículo es analizar la eficacia del uso de la termografía en la evaluación de la biocompatibilidad en la reparación del tejido traqueal, así como identificar procesos inflamatorios tras la implantación de la prótesis impresa en nailon con impresión 3D asociada al elastómero termoplástico - PCTPE. Se dividieron quince conejos blancos de Nueva Zelanda (Oryctolagus cuniculus) machos en tres grupos de diferentes períodos de evaluación (siete, 15 y 30 días). Se implantaron prótesis tridimensionales tras la resección completa de tres anillos traqueales. La evaluación de las imágenes termográficas se realizó en el lugar de implantación de la prótesis traqueal justo antes del procedimiento quirúrgico e inmediatamente antes de la eutanasia. Hubo una diferencia significativa entre los grupos, ya los 30 días la temperatura mínima (p = 0,0357), media (p = 0,0135) y máxima (p = 0,0058) fue menor en comparación con los otros grupos...

Thermography is efficient for detecting body surface temperature and can be used as an auxiliary method for the diagnosis of inflammatory processes and in the evaluation of scarring patterns, which allows its wide use in Veterinary Medicine. The procedure has gained prominence, as it is a non-invasive, painless, low-cost and safe technique, since it does not require the use of contrasts, sedation and radiation. The objective of this article is to analyze the efficiency of the use of thermography in the evaluation of biocompatibility in tracheal tissue repair, as well as to identify inflammatory processes after implantation of the 3D printed impression prosthesis of nylon associated with the thermoplastic elastomer - PCTPE. Fifteen male New Zealand White rabbits (Oryctolagus cuniculus) were divided into three groups of different evaluation periods (seven, 15 and 30 days). Three-dimensional prostheses were implanted after complete resection of three tracheal rings. The evaluation of the thermographic images was performed at the place of implantation of the tracheal prosthesis just before the surgical procedure and immediately before euthanasia. There was a significant difference between the groups, and at 30 days the minimum (p = 0,0357), average (p = 0,0135) and maximum (p = 0,0058) temperature was lower when compared with the other groups...

A termografia é eficiente para detecção da temperatura da superfície corporal e pode ser utilizada como método auxiliar de diagnóstico de processos inflamatórios e na avaliação de padrões cicatriciais, o que permite sua ampla utilização na Medicina Veterinária. O procedimento tem ganhado destaque, pois trata-se de técnica não invasiva, indolor, de baixo custo e segura, pois dispensa a necessidade do uso de contrastes, sedação e radiação.  O objetivo desse artigo é analisar a eficiência do uso da termografia na avaliação da biocompatibilidade em reparação tecidual traqueal, bem como identificar processos inflamatórios após a implantação da prótese impressa em impressão 3D de náilon associado ao elastômero termoplástico- PCTPE. Quinze coelhos machos, da linhagem Nova Zelândia Branco (Oryctolagus cuniculus), foram distribuídos em três grupos de períodos de avaliação diferentes (sete, 15 e 30 dias). As próteses tridimensionais foram implantadas após ressecção completa de três anéis traqueais. A avaliação das imagens termográficas foi efetuada no local de implantação da prótese traqueal no momento anterior ao procedimento cirúrgico e imediatamente antes da eutanásia. Houve diferença significativa entre os grupos, sendo que aos 30 dias a temperatura mínima (p=0,0357), média (p=0,0135) e máxima (p=0,0058) foi menor quando comparado com os demais grupos...

Influence of Incorporating Zirconium- and Barium-based Radiopaque Filler Into Experimental and Commercial Infiltrants.

OBJECTIVES: To evaluate how adding different concentrations of particles (barium or zirconium oxide 25%/45% by weight) to a commercial infiltrant (Icon) and an experimental infiltrant influences cohesive strength (CS), degree of conversion (DC), water sorption (WS), solubility (SL), radiopacity, and penetration depth. METHODS AND MATERIALS: Microtensile CS (n=10) was evaluated using a universal testing machine. DC (n=5) was evaluated in a Fourier-transform infrared spectrometer. Polymerized samples were dissected, weighed, and stored to obtain the final mass for WS and SL tests (n=10). Radiopacity analysis (n=5) was performed using a digital radiography system. Penetration depth analysis (n=5) was performed by confocal laser scanning microscopy. Analyses were performed using the R program, with a significance level of 5%, except for the penetration depth analyses, which were evaluated only qualitatively. RESULTS: The groups with 45% zirconium showed greater CS values, regardless of the infiltrant. Among the groups with no particle addition, those of the experimental infiltrant presented higher DC than those of Icon. The experimental infiltrant presented lower WS than Icon. All groups had SL below the ISO recommended levels. Radiopacity higher than 2.24 mmAl (enamel radiopacity) was observed only in the groups with 45% zirconium. All the groups achieved similar penetration depth, but the groups containing experimental infiltrant appear to have had longer tag extensions. CONCLUSIONS: Addition of 45% of zirconium presented good results for CS and WS, as well as SL below the ISO recommended standard, adequate radiopacity, and penetration depth similar to the other groups.

GSVA score reveals molecular signatures from transcriptomes for biomaterials comparison.

Two in silico methodologies were implemented to reveal the molecular signatures of inorganic hydroxyapatite and ß-TCP materials from a transcriptome database to compare biomaterials. To test this new methodology, we choose the array E-MTAB-7219, which contains the transcription profile of osteoblastic cell line seeded onto 15 different biomaterials up to 48 hr. The expansive potential of the methodology was tested from the construction of customized signatures. We present, for the first time, a methodology to compare the performance of different biomaterials using the transcriptome profile of the cell through the Gene set variation analysis (GSVA) score. To test this methodology, we implemented two methods based on MSigDB collections, using all the collections and sub-collections except the Hallmark collection, which was used in the second method. The result of this analysis provided an initial understanding of biomaterial grouping based on the cell transcriptional landscape. The comparison using GSVA score combined efforts and expand the potential to compare biomaterials using transcriptome profile. Altogether, our results provide a better understanding of the comparison of different biomaterials and suggest a possibility of the new methodology be applied to the prospection of new biomaterials.

Development of an antibacterial and anti-metalloproteinase dental adhesive for long-lasting resin composite restorations.

Despite all the advances in adhesive dentistry, dental bonds are still fragile due to degradation events that start during application of adhesive agents and the inherent hydrolysis of resin-dentin bonds. Here, we combined two outstanding processing methods (electrospinning and cryomilling) to obtain bioactive (antimicrobial and anti-metalloproteinase) fiber-based fillers containing a potent matrix metalloproteinase (MMP) inhibitor (doxycycline, DOX). Poly(ε)caprolactone solutions containing different DOX amounts (0, 5, 25, and 50 wt%) were processed via electrospinning, resulting in non-toxic submicron fibers with antimicrobial activity against Streptococcus mutans and Lactobacillus. The fibers were embedded in a resin blend, light-cured, and cryomilled for the preparation of fiber-containing fillers, which were investigated with antibacterial and in situ gelatin zymography analyzes. The fillers containing 0, 25, and 50 wt% DOX-releasing fibers were added to aliquots of a two-step, etch-and-rinse dental adhesive system. Mechanical strength, hardness, degree of conversion (DC), water sorption and solubility, bond strength to dentin, and nanoleakage analyses were performed to characterize the physico-mechanical, biological, and bonding properties of the modified adhesives. Statistical analyses (ANOVA; Kruskal-Wallis) were used when appropriate to analyze the data (α = 0.05). DOX-releasing fibers were successfully obtained, showing proper morphological architecture, cytocompatibility, drug release ability, slow degradation profile, and antibacterial activity. Reduced metalloproteinases (MMP-2 and MMP-9) activity was observed only for the DOX-containing fillers, which have also demonstrated antibacterial properties against tested bacteria. Adhesive resins modified with DOX-containing fillers demonstrated greater DC and similar mechanical properties as compared to the fiber-free adhesive (unfilled control). Concerning bonding performance to dentin, the experimental adhesives showed similar immediate bond strengths to the control. After 12 months of water storage, the fiber-modified adhesives (except the group consisting of 50 wt% DOX-loaded fillers) demonstrated stable bonds to dentin. Nanoleakage was similar among all groups investigated. DOX-releasing fibers showed promising application in developing novel dentin adhesives with potential therapeutic properties and MMP inhibition ability; antibacterial activity against relevant oral pathogens, without jeopardizing the physico-mechanical characteristics; and bonding performance of the adhesive.

Failure Modes and Survival of Anterior Crowns Supported by Narrow Implant Systems.

The reduced hardware design of narrow implants increases the risk of fracture not only of the implant itself but also of the prosthetic constituents. Hence, the current study is aimed at estimating the probability of survival of anterior crowns supported by different narrow implant systems. Three different narrow implant systems of internal conical connections were evaluated (Ø3.5 × 10 mm): (i) Active (Nobel Biocare), (ii) Epikut (S.I.N. Implant System), and (iii) BLX (Straumann). Abutments were torqued to the implants, and standardized maxillary incisor crowns were cemented. The assemblies were subjected to step-stress accelerated life testing (SSALT) in water through load application of 30 degrees off-axis lingually at the incisal edge of the crowns using a flat tungsten carbide indenter until fracture or suspension. The use level probability Weibull curves and reliability for completion of a mission of 100,000 cycles at 80 N and 120 N were calculated and plotted. Weibull modulus and characteristic strength were also calculated and plotted. Fractured samples were analyzed in a stereomicroscope. The beta (ß) values were 1.6 (0.9-3.1) and 1.4 (0.9-2.2) for BLX and Active implants, respectively, and 0.5 (0.3-0.8) for the Epikut implant, indicating that failures were mainly associated with fatigue damage accumulation in the formers, but more likely associated with material strength in the latter. All narrow implant systems showed high probability of survival (≥95%, CI: 85-100%) at 80 and 120 N, without significant difference between them. Weibull modulus ranged from 6 to 14. The characteristic strength of Active, Epikut, and BLX was 271 (260-282) N, 216 (205-228) N, and 275 (264-285) N, respectively. The failure mode predominantly involved abutment and/or abutment screw fracture, whereas no narrow implant was fractured. Therefore, all narrow implant systems exhibited a high probability of survival for anterior physiologic masticatory forces, and failures were restricted to abutment and abutment screw.

Cell investigation into the biocompatibility of adult human dermal fibroblasts with PCL nanofibers/TiO2 nanotubes on the surface of Ti-30Ta alloy for biomedical applications.

The polymer poly(ε-caprolactone) (PCL) has been used in the biomaterial field for its relatively inexpensive price and suitability for modification. Also, its chemical and biological properties are desirable for biomedical applications. The electrospinning process has been used for producing polymer fibers of PCL due in large part to an increased interest in nanoscale properties and technologies. Moreover, the use of biocompatible polymers for the viability of cell growth is a promising alternative to improve osseointegration. Characterization techniques such as scanning electron microscopy and contact angle were used for analyses of samples. Adult human dermal fibroblasts (neonatal) were utilized to evaluate the biocompatibility of the association of the electrospinning process of the biocompatible polymer (PCL) with TiO2 nanotubes on the Ti-30Ta alloy surface. The results of this study showed a favorable response for adhesion on the surface. This promising material is due to the modulation of the biological response.

Scanning electron microscopy comparison of the resin-dentin interface using different specimen preparation methods.

Microscopy has been widely used to complement the data of studies related to dentin bonding; however, different specimen preparation methods may influence the analysis. Aiming to contribute to the reported scenario, this study evaluated the effect of two specimen-sectioning methods (cleavage and diamond disk cut) on the quality of the scanning electron microscopy (SEM) images. Four crowns of human molars were selected and had an area of approximately 6 mm2 of dentin exposed. They were then divided into two groups according to the universal adhesive application: total and self-etching modes. Then, composite blocks were built up and the specimens were stored in deionized water to allow the postcuring. The specimens were further divided according to the sectioning method: cleavage or diamond disk cut. Four specimens were obtained from each tooth. They were desiccated, placed on aluminum stubs, sputter-coated with gold, and observed in a scanning electron microscope, with ×2000 of magnification. The quality of the SEM images were evaluated by two calibrated examiners and classified into four scores (1-4). Mann-Whitney test (p < .05) showed that the diamond disk provided significantly higher scores than cleavage, whereas no significant difference was observed when comparing the total-etching and self-etching modes of application. The diamond disk cut method is preferable to the cleavage method to ensure the quality of the SEM analysis in studies involving the resin-dentin interface.

Electrospun novel nanocomposite comprising polyurethane integrated with ayurveda amla oil for bone tissue engineering.

Ayurveda oil contains numerous source of biological constituents which plays an important role in reducing the pain relief caused during bone fracture. The aim of the study is to fabricate the polyurethane (PU) scaffold for bone tissue engineering added with ayurveda amla oil using electrospinning technique. Scanning Electron Microscopy (SEM) analysis showed that the fabricated nanocomposites showed reduced fiber diameter (758 ± 185.46 nm) than the pristine PU (890 ± 116.91 nm). Fourier Infrared Analysis (FTIR) revealed the existence of amla oil in the PU matrix by hydrogen bond formation. The contact angle results revealed the decreased wettability (116° ± 1.528) of the prepared nanocomposites compared to the pure PU (100° ± 0.5774). The incorporation of amla oil into the PU matrix improved the surface roughness. Further, the coagulation assay indicated that the addition of amla oil into PU delayed the blood clotting times and exhibited less toxic to red blood cells. Hence, the fabricated nanocomposites showed enhanced physicochemical and better blood compatibility parameters which may serve as a potential candidate for bone tissue engineering.

Micro-computed tomography high resolution evaluation of dimensional and morphological changes of 3 root-end filling materials in simulated physiological conditions.

The aim of this study was to evaluate volumetric and morphological stability of 3 root-end filling materials in addition to porosity and interface voids, using micro-computed tomography (µCT) in high resolution and a highly accurate approach for image analysis. Following root-end resection and apical preparation, two-rooted maxillary premolars were divided into three groups, according to the filling materials: White MTA Angelus, Biodentine, and IRM. Samples were scanned by µCT at 5 µm after the setting time and at time intervals of 7 and 30 days after immersion in phosphate-buffered saline (PBS). Volumetric and morphological changes besides material porosity and interface voids were evaluated by comparing initial values and those obtained after immersion. Data were analyzed statistically, using ANOVA and t-tests (α = 0.05). All materials showed volumetric stability. Regarding the morphological changes, Biodentine had a significant thickness reduction after storage in PBS when compared with MTA. Biodentine also showed an increase in porosity, as well as in percentage and thickness of voids after 30 days of immersion. In conclusion, µCT in high resolution and an accurate image analysis approach may be used to evaluate morphological changes of endodontic materials. Although Biodentine showed suitable adaptability and lower values of porosity than MTA, after PBS immersion there was a dimensional reduction of this material, besides an increase in porosity and interface voids.

Synthesis of bio-based polyurethanes from Kraft lignin and castor oil with simultaneous film formation.

Kraft lignin (KL) and castor oil (CO) were used as polyols in the synthesis of bio-based polyurethanes (PUs) in the absence of both solvents and catalysts at room temperature with simultaneous film formation. KL was purified (PKL), and both KL and PKL were fully characterized. CO was mixed with different percentages of PKL (0%, 10%, 30%, and 50%), as well as with polymeric methyl phenyl diisocyanate. After degassing, the reaction mixture was stirred; when the medium viscosity was suitable for spreading, it was poured onto a glass plate, and the thickness was adjusted using an extender. The storage modulus (E', 25 °C) and tensile strength of the lignopolyurethane films (LignoPUCOPKL) were higher than those of the control film (PUCO). LignoPUCOPKL30 and LignoPUCOPKL50 did not break under the conditions that the other films broke under. It was noted phase segregation (rigid and flexible domains) for LignoPUCOPKL30 and LignoPUCOPKL50, and the glass transition temperature (Tg) of the flexible domains (96.2 °C and 52.3 °C, respectively) was higher than that of PUCO (8.4 °C). The formed films were also characterized by scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, contact angles, and swelling tests. To our knowledge, the approach of this study is unprecedented.

Micro-shear bond strength of adhesives with different degrees of acidity: Effect on sound and artificially hypermineralized dentin.

This study evaluates the bond strength of four self-etching adhesive systems with different acidity levels in normal and artificially hypermineralized dentin substrate. Healthy human molars were divided into groups: normal dentin-N (n = 36) and artificially hypermineralized dentin-H (n = 36). Self-etching adhesive systems Clearfil S3 Bond (n = 9), Optibond All in One (n = 9), Clearfil SE Bond (n = 9), and Adhese (n = 9) were used for both the N and H groups. Transparent cylindrical matrices were positioned on the treated dentin surfaces, filled with composite resin, and light-cured for 40 s. After the transparent cylindrical matrices were removed, the specimens were stored for 24 hr in a humid environment at 37°C and were subjected to a micro-shear bond strength test. For each group, a specimen was prepared and evaluated in scanning electron microscope for adhesive interface observation. Normality was confirmed and the two-way analysis of variance and Games-Howell post-tests were conducted (α = .05). The data demonstrated an interaction between the adhesive system and type of dentin substrate (p < .01). For normal dentin, all adhesive systems assessed were adequate; however, in the hypermineralized dentin, the Clearfil SE Bond two-step self-etching adhesive system with mild pH presented the highest immediate bond strength. There was a predominance of adhesive failures for all adhesive systems in the different dentin substrates evaluated. It was concluded that the self-etching adhesive systems evaluated were efficient for both substrates, and for the hypermineralized dentin, the Clearfil SE Bond presented a higher bond strength value.