Cannabidiol-loaded microparticles embedded in a porous hydrogel matrix for biomedical applications.

In this study, poly (lactic-co-glycolic acid) (PLGA) microparticles loaded with cannabidiol (CBD) were synthesized (PLGA@CBD microparticles) and embedded up to 10 wt% in a chondroitin sulfate/polyvinyl alcohol hydrogel matrix. In vitro chemical, physical, and biological assays were carried out to validate the potential use of the modified hydrogels as biomaterials. The microparticles had spherical morphology and a narrow range of size distribution. CBD encapsulation efficiency was around 52%, loading was approximately 50%. Microparticle addition to the hydrogels caused minor changes in their morphology, FTIR and thermal analyses confirmed these changes. Swelling degree and total porosity were reduced in the presence of microparticles, but similar hydrophilic and degradation in phosphate buffer solution behaviors were observed by all hydrogels. Rupture force and maximum strain at rupture were higher in the modified hydrogels, whereas modulus of elasticity was similar across all materials. Viability of primary human dental pulp cells up to 21 days was generally not influenced by the addition of PLGA@CBD microparticles. The control hydrogel showed no antimicrobial activity against Staphylococcus aureus, whereas hydrogels with 5% and 10% PLGA@CBD microparticles showed inhibition zones. In conclusion, the PLGA@CBD microparticles were fabricated and successfully embedded in a hydrogel matrix. Despite the hydrophobic nature of CBD, the physicochemical and morphological properties were generally similar for the hydrogels with and without the CBD-loaded microparticles. The data reported in this study suggested that this original biomaterial loaded with CBD oil has characteristics that could enable it to be used as a scaffold for tissue/cellular regeneration.

A multi-country survey on the impact of COVID-19 on dental practice and dentists' feelings in Latin America.

BACKGROUND: The COVID-19 pandemic has significantly influenced the routine of healthcare workers. This study investigated the impact of the pandemic on dental practice and dentists' feelings in Latin America. METHODS: A survey was conducted with dentists from 11 Spanish-speaking Latin American countries in September-December 2020. Professionals were invited by email and via an open campaign promoted on social media. The questions investigated dental care routines, practice changes, and feelings about the pandemic. Descriptive statistics were used to identify frequencies and distributions of variables. Proportions were compared using chi-square tests. RESULTS: A total of 2127 responses were collected from a sample with diverse demographic, sex, work, and education characteristics. The impact of COVID-19 was considered high/very high by 60% of respondents. The volume of patients assisted weekly was lower compared with the pre-pandemic period (mean reduction = 14 ± 15 patients). A high rate of fear to contracting the COVID-19 at work was observed (85%); 4.9% of participants had a positive COVID-19 test. The main professional challenges faced by respondents were reduction in the number of patients or financial gain (35%), fear of contracting COVID-19 (34%), and burden with or difficulty in purchasing new personal protective equipment (22%). The fear to contracting COVID-19 was influenced by the number of weekly appointments. A positive test by the dentists was associated with their reports of having assisted COVID-19 patients. The most cited feelings about the pandemic were uncertainty, fear, worry, anxiety, and stress. Negative feelings were more prevalent for professionals who did not receive training for COVID-19 preventive measures and those reporting higher levels of fear to contract the disease. CONCLUSION: This multi-country survey indicated a high impact of the pandemic on dental care routines in Latin America. A massive prevalence of bad feelings was associated with the pandemic.

Effect of the incorporation of hydroxyapatite on the diametral tensile strength of conventional and hybrid glass ionomer cements.

The objective was to evaluate the effect of the incorporation of calcium hydroxyapatite particles (HAp) in the diametral tensile strength of a conventional type II glass ionomer (GC Gold Label 2) and a resin-modified glass ionomer cement (GC Gold Label 2 LC R). Two experimental HAp (E1HAp or E2HAp) were synthesized and characterized using X-ray diffraction and Confocal Raman spectroscopy. Both HAp were added into the powder of a conventional or resin-modified glass ionomer cement at 5 or 10 wt.%. A commercial HAp (CHAp) was used as reference material. For each glass ionomer cement, a group without the incorporation of HAp was used as a control. A universal testing machine was used for the mechanical test. The results were analyzed through a two-way ANOVA test followed by a complementary Tukey test. For all analyzes, the level of significance was set at α = 0.05. The average particle size for E1Hap was 15 µm, E2HAp was 35 µm and for CHAp was 1 µm. For conventional GIC, the addition of 10% E1HAp and 5% CHAp significantly increased the diametral tensile strength values (p ≤ 0.005). On the other hand, for the resin-modified GIC, except for the 5% E2HAp group, all experimental groups significantly reduced the values of diametral tensile strength (p ≤ 0.007). The addition of HAp improved the mechanical properties only for the conventional glass ionomer cement.

Is the use of Cannabis associated with periodontitis? A systematic review and meta-analysis.

Recent studies have shown that there is also biological plausibility for a possible relationship between periodontal disease and Cannabis use, thus the aim of this study was to investigate whether the use of Cannabis is associated with periodontitis. Electronic searches were performed in PubMed, Scopus, ISI-Web of Science, BVS-Virtual health library and Scielo without restrictions. Search strategy was performed using relevant keywords considering the structure of each database. Longitudinal and cross-sectional studies that investigated the association between the use of Cannabis and periodontal disease were included. Meta-analyses and sensitivity analysis were conducted. A total of 143 records were found in the initial searches and five articles were included in the systematic review, being four studies included in the meta-analysis. Overall, 13 491 individuals were included, of which 49.5% were males. Three of included studies investigated the relationship between cannabis and periodontal disease in adults and the other two studies were performed in adolescents. A positive association was observed between the use of cannabis and periodontitis (PR 1.12 CI 95% [1.06-1.19]) with 19.0% of heterogeneity. The analysis of sensibility showed that none study influenced the results enough to change the pooled estimate. Regarding to the quality assessment, all studies presented high quality. The results of systematic review and meta-analyses demonstrate that the use of Cannabis is associated with a higher prevalence of periodontitis.

In vitro characterization of a novel resin-based restorative material containing alkaline fillers.

OBJECTIVE: In this study, a comparative evaluation of the physicochemical properties of Cention N and other direct restorative materials was performed. Three restorative materials-a resin-modified glass ionomer (Fuji II LC), an alkasite-based resinous material (Cention N), and a resin composite (Tetric N Ceram)-were characterized in terms of degree of conversion, Knoop hardness number (KHN) ratio, flexural strength, elastic modulus, water sorption, water solubility, microshear bond strength to dentin, immediate microleakage, and radiopacity. METHODOLOGY: The microshear bond strength to dentin and microleakage of Cention N were evaluated with and without the application of an adhesive system (Tetric N Bond Universal). A one-way ANOVA test was used to analyze the data in terms of degree of conversion, KHN ratio, water sorption, water solubility, microshear bond strength to dentin, and radiopacity. A two-way ANOVA test (carried out considering the material type and ethanol aging as factors) was used to analyze the data in terms of flexural strength and elastic modulus. The Kruskal-Wallis test was used to statistically analyze the data on microleakage. A significance level of α=0.05 was used for all tests. RESULTS: Fuji II LC was found to have the highest degree of conversion, water sorption, and microleakage, as well as the lowest flexural strength. Cention N had the highest solubility; when used with an adhesive system, it achieved bond strength and microleakage similar to those of the Tetric N Ceram composite. Tetric N Ceram had the highest degree of conversion, KHN ratio, and radiopacity. Conclusion: The properties of Cention N validate its efficacy as an alternative direct restorative material when used in conjunction with an adhesive system.

Evaluation of irradiance and radiant exposure on the polymerization and mechanical properties of a resin composite.

The objective of the present study was to evaluate the effect of irradiance and radiant exposure on the chemical-mechanical properties of a resin composite. A micro-hybrid resin composite (Clearfil AP-X, Kuraray) was investigated under two different irradiances: low (300 mW/cm2) and high (800 mW/cm2) and radiant exposures: 8 and 16 J/cm2. Four groups, named Low 8 J/cm2, High 8 J/cm2, Low 16 J/cm2, and High 16 J/cm2 were tested, and their flexural strengths, elastic moduli, depths of cure, and degrees of conversion were evaluated. Data were analyzed using two-way ANOVA and Tukey's test. A multiple linear regression model was used to correlate the irradiance and radiant exposure with dependent variables (α = 0.05). Irradiance and radiant exposure were found statistically significant for all dependent variables. The interaction between the factors was statistically significant only for the degree of conversion and elastic modulus. Group Low 16 J/cm2 exhibited a significantly superior performance in all the evaluated properties. Barring the degree of conversion, no significant differences were observed among the properties evaluated between the Low 8 J/cm2 and High 8 J/cm2 groups. The adjusted R2 values were high for the depth of cure and degree of conversion (0.58 and 0.96, respectively). Both irradiance and radiant exposure parameters play an important role in establishing the final properties of a micro-hybrid resin composite. Irradiance has a greater influence under higher radiant exposures.

Physicochemical characterization of two bulk fill composites at different depths.

OBJECTIVES: This study analyzed the physical-chemical behavior of 2 bulk fill resin composites (BFCs; Filtek Bulk Fill [FBF], and Tetric-N-Ceram Bulk Fill [TBF]) used in 2- and 4-mm increments and compared them with a conventional resin composite (Filtek Z250). MATERIALS AND METHODS: Flexural strength and elastic modulus were evaluated by using a 3-point bending test. Knoop hardness was measured at depth areas 0-1, 1-2, 2-3, and 3-4 mm. The translucency parameter was measured using an optical spectrophotometer. Real-time polymerization kinetics was analyzed using Fourier transform infrared spectroscopy. RESULTS: Flexural strength was similar among the materials, while TBF showed lower elastic modulus (Z250: 6.6 ± 1.3, FBF: 6.4 ± 0.9, TBF: 4.3 ± 1.3). The hardness of Z250 was similar only between 0-1 mm and 1-2 mm. Both BFCs had similar hardness until 2-3 mm, and showed significant decreases at 3-4 mm (FBF: 33.45 ± 1.95 at 0-1 mm to 23.19 ± 4.32 at 3-4 mm, TBF: 23.17 ± 2.51 at 0-1 mm to 15.11 ± 1.94 at 3-4 mm). The BFCs showed higher translucency than Z250. The polymerization kinetics of all the materials were similar at 2-mm increments. At 4-mm, only TBF had a similar degree of conversion compared with 2 mm. CONCLUSIONS: The BFCs tested had similar performance compared to the conventional composite when used in up to 2-mm increments. When the increment was thicker, the BFCs were properly polymerized only up to 3 mm.

Residual Adhesive Removal Methods for Rebonding of Debonded Orthodontic Metal Brackets: Systematic Review and Meta-Analysis.

Debonding of orthodontic brackets is a common occurrence during orthodontic treatment. Therefore, the best option for treating debonded brackets should be indicated. This study aimed to evaluate the bond strength of rebonded brackets after different residual adhesive removal methods. This systematic review and meta-analysis was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. PubMed, Web of Science, The Cochrane Library, SciELO, Scopus, LILACS, IBECS, and BVS databases were screened up to December 2020. Bond strength comparisons were made considering the method used for removing the residual adhesive on the bracket base. A total of 12 studies were included for the meta-analysis. Four different adhesive removal methods were identified: sandblasting, laser, mechanical grinding, and direct flame. When compared with new orthodontic metallic brackets, bond strength of debonded brackets after air abrasion (p = 0.006), mechanical grinding (p = 0.007), and direct flame (p < 0.001) was significantly lower. The use of an erbium-doped yttrium aluminum garnet (Er:YAG) laser showed similar shear bond strength (SBS) values when compared with those of new orthodontic brackets (p = 0.71). The Er:YAG laser could be considered an optimal method for promoting the bond of debonded orthodontic brackets. Direct flame, mechanical grinding, or sandblasting are also suitable, obtaining clinically acceptable bond strength values.

Synthesis and characterization of poly(vinyl alcohol)/chondroitin sulfate composite hydrogels containing strontium-doped hydroxyapatite as promising biomaterials.

Novel poly(vinyl alcohol)/chondroitin sulfate (PVA/CS) composite hydrogels containing hydroxyapatite (HA) or Sr-doped HA (HASr) particles were synthesized by a freeze/thaw method and characterized aiming towards biomedical applications. HA and HASr were synthesized by a wet-precipitation method and added to the composite hydrogels in fractions up to 15 wt%. Physical-chemical characterizations of particles and hydrogels included scanning electron microscopy, energy-dispersive spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetry, porosity, compressive strength/elastic modulus, swelling degree, and cell viability. Particles were irregular in shape and appeared to have narrow size variation. The thermal behavior of composite hydrogels was altered compared to the control (bare) hydrogel. All hydrogels exhibited high porosity. HA/HASr particles reduced total porosity without reducing pore size. The mechanical strength was improved as the fraction of HA or HASr was increased. HASr particles led to a faster water uptake but did not interfere with the total hydrogel swelling capacity. In cell viability essay, increased cell growth (above 120%) was observed in all groups including the control hydrogel, suggesting a bioactive effect. In conclusion, PVA/CS hydrogels containing HA or HASr particles were successfully synthesized and showed promising morphological, mechanical, and swelling properties, which are particularly required for scaffolding.

Simple and Low-Cost Thermal Treatments on Direct Resin Composites for Indirect Use.

The aim of this study was to evaluate the influence of three low-cost additional thermal treatments, available in the dental office, on the mechanical, chemical and optical properties of a light-cured resin composite indicated for direct restorations but used as indirect restorative. The direct resin composite TPH3 (Dentsply) was light-polymerized using a light-emitting diode curing unit and submitted to three experimental additional thermal treatments: dry heat at 170 °C for 5 min, autoclave at 121 °C for 6 min, or microwave oven at 450 W for 3 min. The resin composite without any thermal treatment was used as negative control group. An indirect resin composite (Vita CM LC, Vita Zahnfabrik) was tested as a reference. Flexural strength, elastic modulus, microhardness, degree of C=C conversion, roughness before and after simulated toothbrush abrasion, translucency parameter and color difference (ΔE00) were evaluated. Data were analyzed at α=0.05. The indirect resin composite presented lower C=C conversion and mechanical performance. The flexural strength was significantly higher in the dry oven group compared with the control. The roughness was not different among groups before or after brushing, but the thermal treatments caused an increase in C=C conversion, microhardness, and elastic modulus without affecting the translucency parameter or showing visible color alteration (ΔE00<1.8). These results suggest that the use of additional thermal methods of polymerization represents an economical and simple alternative to enhance the mechanical and chemical properties of direct resin composites when used as indirect restoratives.

Bone, Periodontal and Dental Pulp Regeneration in Dentistry: A Systematic Scoping Review.

The aim of presented systematic scoping review was to investigate the actual and future clinical possibilities of regenerative therapies and their ability to regenerate bone, periodontal and pulp with histological confirmation of the nature of formed tissue. Electronic search was conducted using a combination between Keywords and MeSH terms in PubMed, Scopus, ISI-Web of Science and Cochrane library databases up to January 2016. Two reviewers conducted independently the papers judgment. Screened studies were read following the predetermined inclusion criteria. The included studies were evaluated in accordance with Arksey and O'Malley's modified framework. From 1349 papers, 168 completed inclusion criteria. Several characterized and uncharacterized cells used in Cell Therapy have provided bone regeneration, demonstrating bone gain in quantity and quality, even as accelerators for bone and periodontal regeneration. Synthetic and natural scaffolds presented good cell maintenance, however polyglycolid-polylactid presented faster resorption and consequently poor bone gain. The Growth Factor-Mediated Therapy was able to regenerate bone and all features of a periodontal tissue in bone defects. Teeth submitted to Revascularization presented an increase of length and width of root canal. However, formed tissues not seem able to deposit dentin, characterizing a repaired tissue. Both PRP and PRF presented benefits when applied in regenerative therapies as natural scaffolds. Therefore, most studies that applied regenerative therapies have provided promising results being possible to regenerate bone and periodontal tissue with histological confirmation. However, pulp regeneration was not reported. These results should be interpreted with caution due to the short follow-up periods.

In vitro characterization of a novel resin-based restorative material containing alkaline fillers

Abstract Objective: In this study, a comparative evaluation of the physicochemical properties of Cention N and other direct restorative materials was performed. Three restorative materials—a resin-modified glass ionomer (Fuji II LC), an alkasite-based resinous material (Cention N), and a resin composite (Tetric N Ceram)—were characterized in terms of degree of conversion, Knoop hardness number (KHN) ratio, flexural strength, elastic modulus, water sorption, water solubility, microshear bond strength to dentin, immediate microleakage, and radiopacity. Methodology: The microshear bond strength to dentin and microleakage of Cention N were evaluated with and without the application of an adhesive system (Tetric N Bond Universal). A one-way ANOVA test was used to analyze the data in terms of degree of conversion, KHN ratio, water sorption, water solubility, microshear bond strength to dentin, and radiopacity. A two-way ANOVA test (carried out considering the material type and ethanol aging as factors) was used to analyze the data in terms of flexural strength and elastic modulus. The Kruskal-Wallis test was used to statistically analyze the data on microleakage. A significance level of α=0.05 was used for all tests. Results: Fuji II LC was found to have the highest degree of conversion, water sorption, and microleakage, as well as the lowest flexural strength. Cention N had the highest solubility; when used with an adhesive system, it achieved bond strength and microleakage similar to those of the Tetric N Ceram composite. Tetric N Ceram had the highest degree of conversion, KHN ratio, and radiopacity. Conclusion: The properties of Cention N validate its efficacy as an alternative direct restorative material when used in conjunction with an adhesive system.

Estabilidad dimensional de hidrocoloides irreversibles de vaciado convencional y de vaciado de tiempo extendido disponibles en el mercado uruguayo

Objetivo. Comparar la estabilidad dimensional de un hidrocoloide irreversible de vaciado convencional con hidrocoloides irreversibles de vaciado extendido. Metodología. Fueron evaluados cuatro productos con indicación de vaciado extendido: Jeltrate Plus (Denstply Sirona), Hydrogum 5 (Zhermack SpA), Algimax (Major), Kromopan (Lascod) y un producto de vaciado convencional (Tropicalgin; Zhermack SpA). Con cada producto se realizaron 10 impresiones y se vaciaron en yeso tipo III en cinco tiempos de almacenamiento diferentes (0, 24, 96, 120 y 168 horas). Un escáner para modelos tridimensionales se utilizó para digitalizar los modelos de yeso y realizar las mediciones correspondientes: sumatoria de las longitudes, variabilidad dimensional, porcentaje de variabilidad. Resultados. Las cinco marcas comerciales presentaron una sumatoria de longitudes mayor al grupo control (p<0,033). A las 0, 24 y 96h Tropicalgin e Hydrogum 5 presentaron significativamente menor variación dimensional en comparación con el modelo maestro (p<0,001). Los porcentajes de variabilidad oscilaron entre un 0.24 a 0.91%. Conclusiones. La estabilidad dimensional depende del producto utilizado. Almacenado correctamente, el hidrocoloide irreversible de vaciado convencional parece no sufrir alteraciones significativas hasta 96h, mientras que en el caso de Hydrogum 5 parece mantener su estabilidad dimensional hasta 168h.

Objetivo. Comparar a estabilidade dimensional de um hidrocolóide irreversível de vazamento convencional com hidrocolóides irreversíveis de vazamento prolongado. Metodologia. Foram avaliados quatro produtos com indicação de vazamento estendido: Jeltrate Plus (Denstply Sirona), Hydrogum 5 (Zhermack SpA), Algimax (Major), Kromopan (Lascod) e um produto de vaziamento convencional (Tropicalgin; Zhermack SpA). Para cada produto foram feitas 10 impressões e vazadas em gesso tipo III em cinco tempos de armazenamento diferentes (0, 24, 96, 120 e 168 horas). Um scanner de modelos tridimensionais foi utilizado para digitalizar os modelos de gesso e fazer as medições correspondentes: soma dos comprimentos, variabilidade dimensional, percentagem de variabilidade. Resultados. As cinco marcas comerciais apresentaram somatório de comprimentos maior que o grupo controle (p<0,033). Nos tempos 0, 24 e 96h Tropicalgin e Hydrogum 5 apresentaram variação dimensional significativamente menor em comparação ao modelo Mestre (p<0,001). Os percentuais de variabilidade variaram de 0,24 a 0,91%. Conclusões. A estabilidade dimensional depende do produto utilizado. Armazenado corretamente, o hidrocolóide irreversível de vaziamento convencional convencionalmente parece não sofrer alterações significativas até 96h, enquanto no caso do Hydrogum 5 parece manter sua estabilidade dimensional até 168h.

Aim . Compare the dimensional stability of a conventional pouring irreversible hydrocolloid with extended pouring irreversible hydrocolloids. Methodology. Four products with extended emptying indication were evaluated: Jeltrate Plus (Denstply Sirona), Hydrogum 5 (Zhermack SpA), Algimax (Major), Kromopan (Lascod) and a conventional emptying product (Tropicalgin; Zhermack SpA). For each product, 10 impressions were made and cast in type III plaster at five different storage times (0, 24, 96, 120 and 168 hours). A three-dimensional model scanner was used to digitize the plaster models and make the corresponding measurements: sum of lengths, dimensional variability, percentage of variability. Results . The five commercial brands presented a greater sum of lengths than the control group (p<0,033). At 0, 24 and 96h Tropicalgin and Hydrogum 5 presented significantly less dimensional variation compared to the master model (p<0,001). The variability percentages ranged from 0.24 to 0.91%. Conclusions. Dimensional stability depends on the product used. Stored correctly, the conventionally cast irreversible hydrocolloid appears not to undergo significant alterations up to 96h, while in the case of Hydrogum 5 it appears to maintain its dimensional stability up to 168h.

Bleaching and enamel surface interactions resulting from the use of highly-concentrated bleaching gels.

Tooth bleaching is considered a non-invasive treatment, although the use of highly-concentrated products may provoke increased surface roughness and enamel demineralization, as well as postoperative sensitivity. Thus, the aim of this study was to investigate whether hydrogen peroxide (H2O2) concentration would affect tooth bleaching effectiveness and the enamel surface properties. Enamel/dentin bovine specimens (6 × 4 mm) were immersed in coffee solution for 7 days and evaluated with a spectrophotometer (Easyshade; baseline), using the CIEL*a*b* color parameters. Hardness was measured using a hardness tester. The specimens were randomly assigned into four groups: one negative control, in which the specimens were not bleached, but they were irradiated with a laser-light source (Whitening Lase II, DMC Equipments); and three groups using distinct H2O2 concentration, namely LP15% (15% Lase Peroxide Lite), LP25% (25% Lase Peroxide Sensy), and LP35% (35% Lase Peroxide Sensy), all products from DMC. The bleached specimens were also irradiated with the laser-light source. After bleaching, all specimens were evaluated using scanning electron microscopy (SEM). pH kinetics and rate was monitored during bleaching. The data were analyzed using ANOVA and Tukey's test (p < 0.05). All bleaching gels produced similar color change (p > 0.05). Concerning hardness, only the LP25% and LP35% significantly reduced hardness after bleaching; also, there was a progressive tendency for a greater percentage reduction in hardness with increased H2O2 concentration of the gel (R2 = 0.9973, p < 0.001). SEM showed that LP25% and LP35% produced an etching pattern on enamel with prism rods exposure. In conclusion, H2O2 concentration above the 15% level does not increase bleaching effectiveness, and may increase the possibility for alteration of enamel hardness, surface morphology, and acidity of the medium. When using H2O2-based bleaching agents, dental practitioners should choose for less concentrated gels, e.g., around the 15% level.

Resistencia de unión al cizallamiento de diferentes agentes de fijación a aleaciones metálicas odontológicas / Shear bond strength of different bonding agents to dental metal alloys

Introducción: La fijación de las restauraciones indirectas es uno de los pasos más importantes, para conseguir una adecuada retención y sellado de la interfase entre el material restaurador y el diente. Objetivo: Evaluar la resistencia de unión al cizallamiento de diferentes agentes de fijación a dos aleaciones metálicas utilizadas en odontología. Métodos: Estudio experimental in vitro. Cien especímenes de aleaciones de metales base, 50 de níquel-cromo y 50 de níquel-cromo-titanio fueron preparados y divididos de manera aleatoria en 5 grupos. Esta división se realizó acorde con el agente de fijación utilizado: sistema autograbante de dos pasos (Clearfil SE Bond; CSB), sistema adhesivo universal (Single Bond Universal; SBU), cemento resinoso autoadhesivo (Maxcem Elite; ME), ionómero de vidrio (IV) y fosfato de zinc (ZnPO). Posteriormente a la aplicación de cada agente de fijación, los especímenes tratados fueron almacenados en agua destilada por 24 h a 37 ºC y sometidos a un ensayo de resistencia de unión al cizallamiento. Resultados: La resistencia de unión al cizallamiento fue influenciada significativamente por el tipo de agente de fijación (p = 0,002) y el tipo de aleación utilizada (p < 0,001). La resistencia de unión al cizallamiento fue mayor, al utilizar el sistema Clearfil SE Bond, seguida de Single Bond Universal; las diferencias entre Maxcem Elite y el Fosfato de zinc no fueron significativas. Finalmente, el IV no mostró adhesión a ninguna de las aleaciones metálicas utilizadas. Conclusiones: El uso de Clearfil SE Bond aumentó la resistencia de unión de los cementos resinosos a las aleaciones metálicas(AU)

Introduction: The bonding of indirect restorations is one of the most important steps, in order to achieve adequate retention and sealing of the interface between the restorative material and the tooth. Objective: To evaluate the shear bond strength of different bonding agents to two metal alloys used in dentistry. Methods: In vitro experimental study. One hundred specimens of base metal alloys, 50 nickel-chromium and 50 nickel-chromium-titanium were prepared and randomly divided into 5 groups. This division was made according to the bonding agent used: two-step self-etching system (Clearfil SE Bond; CSB), universal adhesive system (Single Bond Universal; SBU), self-adhesive resin cement (Maxcem Elite; ME), glass ionomer (IV) and zinc phosphate (ZnPO). After the application of each bonding agent, the treated specimens were stored in distilled water for 24 hr at 37 ºC and subjected to a shear bond strength test. Results: Shear bond strength was significantly influenced by the type of bonding agent (p = 0.002) and the type of alloy used (p < 0.001). Shear bond strength was highest when using the Clearfil SE Bond system, followed by Single Bond Universal; the differences between Maxcem Elite and Zinc Phosphate were not significant. Finally, IV did not show adhesion to any of the metal alloys used. Conclusions: The use of Clearfil SE Bond increased the bond strength of resinous cements to metallic alloys(AU)

Examining the Effect of Radiant Exposure on Commercial Photopolimerizable Dental Resin Composites.

The objective of this study was to evaluate the effect of radiant exposure on the chemical and physical properties of four commercial dental resin composites. The four dental resin composites used were Kalore, Admira, Tetric N-Ceram Bulk Fill, and Filtek Z350 XT. The composites were subjected to three curing protocols: 1000 mW/cm² for 5 s, 1000 mW/cm² for 10 s, and 400 mW/cm² for 25 s. The flexural strength, elastic modulus, water sorption, water solubility, degree of conversion, and polymerization shrinkage were evaluated. The results were analyzed by means of ANOVA and Tukey tests. For Admira and Kalore, significant differences between light exposure protocols were observed for the elastic modulus (p < 0.001), which was higher when a higher amount of radiant exposure was used. For Filtek Z350, differences were only observed for the degree of conversion (p < 0.001), and a higher amount of radiant exposure allowed us to obtain higher values. The Tetric N-Ceram Bulk Fill analysis showed significant differences for the elastic modulus and water sorption (p < 0.001), and specimens that had been subject to a radiant exposure of 10 J/cm² showed a higher elastic modulus. In most cases, the physical and mechanical properties analyzed were not affected by different radiant exposure values. Other resin-based composite (RBC) characteristics seem to have a greater influence on material properties.

Decálogo de buenas prácticas para el uso y mantenimiento de las Unidades de Fotocurado LEDs

Actualmente varios biomateriales restauradores resinosos endurecen mediante una reacción de fotopolimerización, para lo cual es necesaria una unidad de polimerización (UP). El objetivo de este manuscrito es generar una guía basada en la evidencia científica actual para contribuir al correcto uso de las UP. Se realizó una búsqueda de artículos publicados desde el año 2002 hasta enero del 2022 a través de PubMed y Google Scholar. Se organizó la información en 10 tópicos de relevancia en forma de decálogo: longitud de onda, intensidad de la luz, diámetro de la punta, tiempo de curado, modo de curado, distancia de curado, uso de barreras, batería y carga, limpieza y desinfección, finalizando con los controles periódicos. Los profesionales de la salud deben conocer y recordar la importancia de realizar un adecuado uso y mantenimiento de las UP, ya que esto puede influir en el desempeño clínico de los biomateriales.

Atualmente, diversos biomateriais restauradores resinosos endurecem através de uma reação de fotopolimerização, para a qual é necessária uma unidade de polimerização (UP). O objetivo deste manuscrito é gerar um guia baseado em evidências científicas atuais para o uso correto de UPs. Foi feita uma busca por artigos publicados de 2002 a janeiro de 2022 por meio do PubMed e Google Scholar. As informações foram organizadas em 10 tópicos relevantes na forma de um decálogo: comprimento de onda, intensidade da luz, diâmetro da ponta, tempo de cura, modo de cura, distância de cura, uso de barreiras, bateria e carregamento, limpeza e desinfecção e verificações regulares. Os profissionais de saúde devem conhecer e lembrar a importância do uso e manutenção adequados das UPs, pois isso pode influenciar no desempenho clínico do biomaterial.

Efecto de la intensidad de las unidades de fotopolimerización sobre la biocompatibilidad y resistencia a la flexión de una resina compuesta

Objetivo: Determinar el efecto de la intensidad de dos unidades de fotopolimerización sobre la biocompatibilidad, resistencia flexural y módulo elástico de una resina compuesta. Metodología: Se crearon dos grupos de resina compuesta Filtek Z250XT cada uno fotopolimerizado con intensidades diferentes (800 mW/cm2 por 20s). La viabilidad celular fue analizada mediante ensayo de MTT a las 24 y 48 horas siguiendo la normativa ISO 10993-5. La resistencia flexural y módulo elástico fueron analizadas siguiendo la normativa ISO 4049. Resultados: En el grupo fotopolimerizado con una intensidad <400 mW/cm2, la citotoxicidad fue estadísticamente mayor tanto a las 24 como a las 48 horas y la resistencia flexural y módulo elástico fueron estadísticamente menores Conclusión: Una intensidad de polimerización <400 mW/cm2, aumenta los niveles de citotoxicidad y disminuye las propiedades mecánicas de las resinas compuestas. Se destaca la importancia del control periódico de las unidades de fotopolimerización.

Objetivo: Determinar o efeito da intensidade de duas unidades de fotopolimerização na biocompatibilidade, resistência à flexão e módulo de elasticidade de uma resina composta. Metodologia: Foram fabricados dois grupos de resina composta Filtek Z250XT, cada um deles foi fotopolimerizado com intensidades diferentes ( 800 mW/cm2 por 20s). A viabilidade celular foi analisada por ensaio de MTT em 24 e 48 horas seguindo a norma ISO 10993-5. A resistência à flexão e o módulo de elasticidade foram analisados ​​seguindo a norma ISO 4049. Resultados: No grupo fotopolimerizado com intensidade <400mW/cm2, a citotoxicidade foi estatisticamente maior nas 24 e 48 horas e a resistência à flexão e o módulo de elasticidade foram estatisticamente menores. Conclusão: Uma intensidade de polimerização <400 mW/cm2 aumenta os níveis de citotoxicidade e diminui as propriedades mecânicas das resinas compostas. Destaca-se a importância do controle periódico das unidades de fotopolimerização.

Objective: To determine the effect of the intensity of two light curing units on the biocompatibility, flexural strength and elastic modulus of a composite resin. Methodology: Two groups of Filtek Z250XT (3M ESPE) composite resin were created, each one photopolymerized using different intensities ( 800 mW/cm2 for 20s). Cell viability was analyzed by MTT assay at 24 and 48 hours following the ISO 10993-5 standard. The flexural strength and elastic modulus were analyzed following the ISO 4049 standard. Results: In the group photopolymerized with an intensity <400 mW/cm2, cytotoxicity was statistically higher both at 24 and 48 hours and flexural strength and elastic modulus were statistically lower. Conclusion: A polymerization intensity <400 mW/cm2 increases the levels of cytotoxicity and decreases the mechanical properties of composite resins. The importance of the periodic control of the light curing units is emphasized.

Evaluation of irradiance and radiant exposure on the polymerization and mechanical properties of a resin composite

Abstract The objective of the present study was to evaluate the effect of irradiance and radiant exposure on the chemical-mechanical properties of a resin composite. A micro-hybrid resin composite (Clearfil AP-X, Kuraray) was investigated under two different irradiances: low (300 mW/cm2) and high (800 mW/cm2) and radiant exposures: 8 and 16 J/cm2. Four groups, named Low 8 J/cm2, High 8 J/cm2, Low 16 J/cm2, and High 16 J/cm2 were tested, and their flexural strengths, elastic moduli, depths of cure, and degrees of conversion were evaluated. Data were analyzed using two-way ANOVA and Tukey's test. A multiple linear regression model was used to correlate the irradiance and radiant exposure with dependent variables (α = 0.05). Irradiance and radiant exposure were found statistically significant for all dependent variables. The interaction between the factors was statistically significant only for the degree of conversion and elastic modulus. Group Low 16 J/cm2 exhibited a significantly superior performance in all the evaluated properties. Barring the degree of conversion, no significant differences were observed among the properties evaluated between the Low 8 J/cm2 and High 8 J/cm2 groups. The adjusted R2 values were high for the depth of cure and degree of conversion (0.58 and 0.96, respectively). Both irradiance and radiant exposure parameters play an important role in establishing the final properties of a micro-hybrid resin composite. Irradiance has a greater influence under higher radiant exposures.

Venous Blood Derivatives as FBS-Substitutes for Mesenchymal Stem Cells: A Systematic Scoping Review.

Although the biological properties of mesenchymal stem cells (MSC) are well-characterized in vitro, MSC clinical application is still far away to be achieved, mainly due to the need of xenogeneic substances for cell expansion, such as fetal bovine serum (FBS). FBS presents risks regarding pathogens transmissions and internalization of animal's proteins, which can unleash antigenic responses in patients after MSC implantation. A wide range of venous blood derivatives (VBD) has been reported as FBS substitutes showing promising results. Thus, the aim of this study was to conduct a systematic scoping review to analyze whether VBD are effective FBS substitutes for MSC ex vivo expansion. The search was performed in SciVerse ScopusTM, PubMed, Web of ScienceTM, BIREME, Cochrane library up to January 2016. The keywords were selected using MeSH and entry terms. Two independent reviewers scrutinized the records obtained considering specific inclusion criteria. The included studies were evaluated in accordance with a modified Arksey and O' Malley's framework. From 184 found studies, 90 were included. Bone marrow mesenchymal stem cells (BMMSC) were presented in most of these studies. Overall, VBD allowed for either, maintenance of MCS's fibroblast-like morphology, high proliferation, high colony-formation ability and maintenance of multipotency. Besides. MSC expanded in VBD supplements presented higher mitogen activity than FBS. VBD seems to be excellent xeno-free serum for ex vivo expansion of mesenchymal stem cells. However, an accentuated heterogeneity was observed between the carried out protocols for VBD isolation did not allowing for direct comparisons between the included studies.