Pontos quânticos estabilizados por líquido iônico como estratégia de carga nanométrica não aglomerada em resina adesiva

O objetivo desse estudo foi formular e avaliar resinas adesivas experimentais com diferentes concentrações de pontos quânticos de dióxido de titânio com líquido iônico (TiO2QDs/BMI.BF4). TiO2QDs/BMI.BF4 foram sintetizados com tetracloreto de titânio e líquido iônico (LI). Os adesivos foram formulados com bisfenol A glicidil metacrilato, hidroxietil metacrilato e sistema fotoiniciador. TiO2QDs/BMI.BF4 foram incorporados em 2,5% (G2,5%) e 5% (G5%) ao adesivo e um grupo permaneceu sem carga como grupo controle (GC). TiO2QDs/BMI.BF4 foram analisados por espectroscopia μ-Raman, termogravimetria, microscopia eletrônica de transmissão (MET) e microscopia de fluorescência. Os adesivos foram avaliados quanto à atividade antibacteriana imediata e longitudinal (n=3), citotoxicidade (n=3), cinética de polimerização (n=3), dureza Knoop (n=3) amolecimento em solvente (n=3), resistência de união (μ-TBS) imediata e longitudinal (n=20) e padrão de fratura. TiO2QDs/BMI.BF4 apresentaram tamanho mínimo de 1,19 nm, mediana de 3,5 nm e máximo de 7,11 nm; picos de anatase e rutilo e ~26% de LI. TiO2QDs/BMI.BF4 se mostraram bem dispersos com fluorescência intermitente. G2,5% e G5% apresentaram atividade antibacteriana imediata e longitudinal quanto à formação de biofilme comparados a GC (p0,05). Não houve diferença quanto à microdureza inicial (p=0,909) e μ-TBS imediata (p=0,239). G5% apresentou maior amolecimento em solvente (p=0,021) e menor μ-TBS longitudinal (p0.05). There was no difference in the initial microhardness (p=0.909) and the immediate μ-TBS (p=0.239). G5% presented the highest softening in solvent (p=0.021) and the lowest longitudinal μ-TBS (<0.001), with predominance of mixed fracture for all groups. It was concluded that the addition of quantum dots stabilized by IL is a promising strategy for the development of polymers with non-agglomerated nanofillers

Surface and mechanical properties of adhesives with calcium phosphates challenged to different storage media

To evaluate the behavior of experimental dental adhesives with hydroxyapatite (HAp), alpha-tricalcium phosphate (α-TCP) or octacalcium phosphate (OCP) after storing them in three different media: dry storage, distilled water, or lactic acid. Methods: An experimental adhesive resin was formulated with bisphenol A glycol dimethacrylate, 2-hydroxyethyl methacrylate, and photoiniciator/co-initiator system. HAp (GHAp), α-TCP (Gα-TCP), or OCP (GOCP) were added to the adhesive resin at 2 wt.%, and one group remained without calcium phosphates to be used as a control (GCtrl). The adhesives were evaluated for surface roughness, scanning electron microscopy (SEM), and ultimate tensile strength (UTS) after storing in distilled water (pH=5.8), lactic acid (pH=4) or dry medium. Results: The initial surface roughness was not different among groups (p>0.05). GHAp showed increased values after immersion in water (p<0.05) or lactic acid (p<0.05). SEM analysis showed a surface variation of the filled adhesives, mainly for Gα-TCP and GHAp. GHAp showed the highest UTS in dry medium (p<0.05), and its value decreased after lactic acid storage (p<0.05). Conclusions: The findings of this study showed that HAp, OCP, and α-TCP affected the physical behavior of the experimental adhesive resins in different ways. HAp was the calcium phosphate that most adversely affected the surface roughness and the mechanical property of the material, mainly when exposed to an acid mediu

Evaluation of guanidine antifungal solutions for denture base resin: an in vitro study

Antecedentes: Os objetivos deste estudo foram: (1) formular soluções de cloridrato de polihexametileno guanidina (PHM-GH) em diferentes concentrações; (2) avaliar sua atividade antifúngica contra biofilme maduro de Candida albicans em resinas acrílicas; (3) avaliar efeitos na resistência à flexão e rugosidade da superfície. Métodos: Soluções de PHMGH foram formuladas com água destilada e 0,125, 0,250 ou 0,5% em peso de PHMGH. Um grupo sem PHMGH foi usado como controle. Para análise da atividade antifúngica, amostras de resina acrílica foram contaminadas com C. albicans, e imersas em soluções de PHMGH ou água destilada por 5 ou 10 min. Resistência à flexão final e rugosidade da superfície foram avaliadas. Resultados: Todas as soluções de PHMGH aos 5 ou 10 minutos apresentaram atividade antifúngica em comparação ao grupo controle (pBackground: The purposes of this study were: (1) to formulate polyhexamethylene guanidine hydrochloride (PHMGH) solutions at different concentrations; (2) to evaluate their antifungal activity against a mature biofilm of Candida albicans on acrylic resins; (3) to evaluate possible effects on acrylic resins flexural strength and surface roughness. Methods: PHMGH solutions were formulated with distilled water and 0.125, 0.250, or 0.5 wt.% of PHMGH. One group without PHMGH was used as control. For antifungal activity analysis, acrylic resin specimens were contaminated with C. albicans. Specimens were immersed in PHMGH solutions or distilled water for 5 or 10 min. Ultimate flexural strength and surface roughness of acrylic resins were evaluated. Results: All PHMGH solutions at 5 or 10 min showed antifungal activity compared to the control group (

Análisis de la distribución de microdureza, contenido mineral y orgánico de dientes humanos, bovinos y ovinos

Objetive. Human teeth have been commonly used for in vitro and in situ studies. Cu­rrently, other animals’ teeth have been purposed for dental research to overcome human teeth’ problematic availability. This study aimed to investigate the enamel and dentin from human, bovine, and ovine teeth concerning the microhardness, organic, and inorganic contents via micro-Raman spectroscopy. Methods. Human, bovine, and ovine teeth were divided according to their type and age into seven groups: Ovine; Bovine-12 months; Bovine-24 months; Bovine-36 months; Bovine-48 months; Bovine-+60 months; Human (control). The enamel’s microhardness (superficial and deep) and dentin (superficial, middle, and deep) were analyzed. The calcium/phosphate ratio and amide contents were determined by micro-Raman spectroscopy. Results. Overall, the microhardness of human enamel was superior to the other species. Dentin’s microhardness was similar among groups. Ovine group showed lower values of calcium/phosphate ratio than human. Amide content was similar between bovine and human. The microhardness and calcium/phosphate ratio of enamel and dentin, respectively, decreased as the age of bovine teeth increased. Conclusions. Researchers must be aware and take into consideration the differences of ovine and bovine enamel compared to human enamel. Other alternatives that are more similar to the microhardness of human enamel should be sought. Bovine teeth of 12 and 24 months are suitable substitutes for dentin of human teeth. Researchers must also be aware of the age of the animals and specify it in the studies.Objetivo. Los dientes humanos se han utilizado comúnmente para estudios in vitro e in situ. Actualmente, los dientes de otros animales se han destinado a la investigación dental para superar la disponibilidad problemática de los dientes humanos. Este estudio tuvo como objetivo investigar el esmalte y la dentina de los dientes humanos, bovinos y ovinos en relación con la microdureza y los contenidos orgánicos e inorgánicos a través de la espectroscopia micro-Raman. Métodos. Los dientes humanos, bovinos y ovinos se dividieron según su tipo y edad en siete grupos: Ovinos; Bovino-12 meses; Bovino-24 meses; Bovino-36 meses; Bovino-48 meses; Bovino-+60 meses; Humano (control). Se analizó la microdureza del esmalte (superficial y profunda) y de la dentina (superficial, media y profunda). La relación calcio/fosfato y los contenidos de amida se determinaron mediante espectroscopía micro-Raman. Resultados. En general, la microdureza del esmalte humano fue superior a la de otras especies. La microdureza de la dentina fue similar entre los grupos. El grupo ovino mostró valores más bajos de la relación calcio/fosfato que el humano. El contenido de amida fue similar entre bovinos y humanos. La microdureza y la relación calcio/fosfato del esmalte y la dentina, respectivamente, disminuyeron a medida que aumentaba la edad de los dientes bovinos. Conclusiones. El esmalte de los dientes ovinos y bovinos no es un sustituto adecuado del de los dientes humanos. Se deben buscar otras alternativas que sean similares a la microdureza del esmalte humano. Sin embargo, los dientes bovinos de 12 y 24 meses son sustitutos adecuados de la dentina de los dientes humanos. Los investigadores deben conocer la edad de los animales y especificarla en los estudios

Effect of silver nanoparticles on the physicochemical and antimicrobial properties of an orthodontic adhesive

Orthodontic treatment with fixed brackets plays a major role on the formation of white spot lesions. Objective This study aimed to incorporate silver nanoparticle solutions (AgNP) in an orthodontic adhesive and evaluate its physicochemical and antimicrobial properties. Material and Methods Silver nanoparticle solutions were added to a commercial adhesive in different concentrations (w/w): 0%, 0.11%, 0.18%, and 0.33%. Shear bond strength (SBS) test was performed after bonding metal brackets to enamel. Raman spectroscopy was used to analyze in situ the degree of conversion (DC) of the adhesive layer. The surface free energy (SFE) was evaluated after the measurement of contact angles. Growth inhibition of Streptococcus mutans in liquid and solid media was determined by colony-forming unit count and inhibition halo, respectively. One-way ANOVA was performed for SBS, DC, SFE, and growth inhibition. Results The incorporation of AgNP solution decreased the SBS (

Effect of silver nanoparticles on the physicochemical and antimicrobial properties of an orthodontic adhesive

Ortodontiv treatment with fixed brackets plays a mayor role on the formation of white spot lesions. Objective:Tadhesive and evaluate its physicochemical and antimicrobial properties. Material and Methods: Silver nanoparticle solutions were added to a commercial adhesive in different concentrations (w/w): 0%, 0.11%, 0.18%, and 0.33%. Shear bond strength (SBS) test was performed after bonding metal brackets to enamel. Raman spectroscopy was used to analyze in situ the degree of conversion (DC) of the adhesive layer. The surface free energy (SFE) was evaluated after the measurement of contact angles. Growth inhibition of Streptococcus mutans in liquid and solid media was determined by colony-forming unit count and inhibition halo, respectively. One-way ANOVA was performed for SBS, DC, SFE, and growth inhibition. Results: The incorporation of AgNP solution decreased the SBS (p<0.001) and DC in situ (p<0.001) values. SFE decreased after addition of 0.18% and 0.33% AgNP. Growth inhibition of S. mutans in liquid media was obtained after silver addition (p<0.05). Conclusions: The addition of AgNP solutions to Transbond™ XT adhesive primer inhibited S. mutans growth. SBS, DC, and SFE values decreased after incorporation up to 0.33% AgNP solution without compromising the chemical and physical properties of the adhesive

Influence of Different Thickness in the Degree of Conversion of an Adhesive Resin.

Objetivos: o objetivo desse trabalho foi avaliar o grau de conversão (GC) de diferentes espessuras (1; 2; 3 e 4 mm) de uma resina adesiva translúcida de uso odontológico. Materiais e métodos: o GC de uma resina adesiva translúcida foi avaliado por meio de espectroscopia no infravermelho por transformada de Fourier (FTIR) acoplado a um dispositivo de refletância total atenuada (ATR). Foram utilizadas quatro matrizes de polivinilsiloxano de 1; 2; 3 ou 4 mm de espessura por 7 mm de diâmetro cada uma para conter o adesivo dispensado (n = 3) sobre o cristal de diamante do dispositivo de ATR. ANOVA de uma via e teste de comparações múltiplas de Student-Newman-Keuls foram utilizados com um nível de significância estatística de 5%. Resultados: espécimes de 1 mm de espessura apresentaram estatisticamente maiores valores de GC (62,19± 0,20) comparado aos demais grupos (p0,05), mas foram maiores que o grupo de 4mm (p>0,05). Conclusão: é necessária a padronização da espessura dos espécimes submetidos ao ensaio de avaliação de GC por FTIR-ATR.Aim: the purpose of this study was to evaluate the degree of conversion (DC) of different thicknesses (1, 2, 3 and 4 mm) of a translucent dental adhesive resin Materials and Methods: the degree of conversion (DC) of adhesive resins was measured by Fourier Transform Infrared Spectroscopy (FTIR) equipped with an attenuated total reflectance device (ATR). It were used four matrices of polyvinylsiloxane with dimensions of 1; 2; 3 or 4 mm in thickness and 7 mm in diameter each one to contain the dispensed adhesive (n = 3) on the diamond crystal of the ATR device. The data were analyzed by one-way ANOVA and Student-Newman-Keels’ post hoc test (α=0.05). Results: specimens of 1 mm of thickness showed statistically higher DC (62.19 ± 0.20) compared to the other groups (p0.05), but groups of 2 and 3 mm showed higher DC than the group of 4 mm (

Myristyltrimethylammonium Bromide (MYTAB) as a cationic surface agent to inhibit Streptococcus mutans grown over dental resins: an in vitro study

This in vitro study evaluated the effect of myristyltrimethylammonium bromide (MYTAB) on the physical, chemical, and biological properties of an experimental dental resin. The resin was formulated with dental dimetacrylate monomers and a photoinitiator/co-initiator system. MYTAB was added at 0.5 (G0.5%), 1 (G1%), and 2 (G2%) wt %, and one group remained without MYTAB and was used as the control (GCtrl). The resins were analyzed for the polymerization kinetics, degree of conversion, ultimate tensile strength (UTS), antibacterial activity against Streptococcus mutans, and cytotoxicity against human keratinocytes. Changes in the polymerization kinetics profiling were observed, and the degree of conversion ranged from 57.36% (±2.50%) for G2% to 61.88% (±1.91%) for G0.5%, without a statistically significant difference among groups (p > 0.05). The UTS values ranged from 32.85 (±6.08) MPa for G0.5% to 35.12 (±5.74) MPa for GCtrl (p > 0.05). MYTAB groups showed antibacterial activity against biofilm formation from 0.5 wt % (p 0.05). In conclusion, the addition of 0.5 wt % of MYTAB did not alter the physical and chemical properties of the dental resin and provided antibacterial activity without cytotoxic effect

Evaluation of the physicochemical and antibacterial properties of experimental adhesives doped with lithium niobate

The aim of the present study was to formulate dental adhesives with different concentrations of LiNbO3 and to evaluate their physicochemical and antibacterial properties. A dental adhesive was formulated using methacrylate monomers and photoinitiators and used as a control filler-free group. Subsequently, three experimental adhesives doped with LiNbO3 at different concentrations (1 wt.%, 2 wt.%, and 5 wt.%) were also formulated. All the experimental adhesives were assessed to evaluate the degree of conversion (DC), softening in solvent, immediate and long-term microtensile bond-strength (μ-TBS), radiopacity, ultimate tensile strength, and antibacterial activity. The incorporation of 1 wt.% of LiNbO3 had no negative effect on the DC of the adhesive resin compared to the control group (p > 0.05). We observed a decrease in the percentage of softening in solvent in the group LiNbO3 at 1 wt.% (p 0.05). After six months, the group with 5 wt.% still presented the highest μ-TBS (p 0.05). LiNbO3 was successfully incorporated in dental adhesives, increasing the radiopacity and their resistance to degradation. Although LiNbO3 offered no antibacterial properties, the reliability of LiNbO3 incorporation in the adhesive encourages new tests to better investigate the antimicrobial action of LiNbO3 through temperature variation