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Antimicrobial activity and physicochemical performance of a modified endodontic sealer
2020 - GONCALVES, FLAVIA; CAMPOS, LUIZA M. de P.; SANCHES, LUCIANA K.F.; SILVA, LARISSA T.S.; SANTOS, TAMIRIS M.R. dos; VARCA, GUSTAVO H.C.; LOPES, DIANA P.; COGO-MULLER, KARINA; PARRA, DUCLERC F.; BRAGA, ROBERTO R.; SANTOS, MARCELO dos; BOARO, LETICIA C.C.
Introduction: this study aimed to evaluate the antimicrobial and physicochemical properties of a commercial endodontic sealer modified by the addition of montmorillonite (MMT) nanoparticles loaded with two different drugs: chlorhexidine (CHX) or metronidazole (MET). Methods: 5 wt% MMT/CHX or MMT/MET nanoparticles were added to the sealer AH-Plus. The experimental materials were evaluated for drug release, antimicrobial activity, flow, flexural strength, and flexural modulus. Data were subjected to one-way ANOVA, Kruskal-Wallis, and Mann-Whitney tests. Results: The drug incorporation into MMT particles was 9% and 10% for CHX and MET, respectively. At 20 days after manipulation, 16.5% of the drug was released by the sealer with MMT/MET and 0.4% by MMT/CHX. The addition of both nanoparticles decreased the flow of materials, but they were still in compliance with ISO 6876-2012. The conversion, flexural strength, and flexural modulus of MMT/MET (87%, 37±7 MPa, 2.3 GPa) and MMT/CHX (78%, 29±2 MPa, 2.7 GPa) were similar in both groups but lower than in the control group (100%, 54±7 MPa, 4.0±0.7 GPa). Both experimental materials were able to form an inhibition halo for E. faecalis bacteria (CHX: 4.8±1.4 and MET: 4.0±1.6 mm), whereas the control group did not inhibit the microorganism. Conclusion: both formulations proposed as endodontic sealer presented effective antimicrobial activity and acceptable flow. The addition of MMT/CHX and MMT/MET particles decreased the conversion and mechanical properties, but further studies are required to clarify the clinical relevance of these properties.
Estudo da liberação de clorexidina incorporada em nanopartículas de montmorilonita em compósitos a base de BisGMA/TEGDMA
2016 - CAMPOS, L.M.P.; BOARO, L.C.C.; SANTOS, T.M.R.; VARCA, G.H.C.; SANTOS, L.K.G.; LUGAO, A.B.; PARRA, D.F.
O objetivo desse estudo foi desenvolver nanocompósitos experimentais adicionados com nanopartículas de Montmorilonita (MMT) incorporadas com diacetato de clorexidina (CHX) como carga, em uma matriz polimérica a base de BisGMA/TEGDMA (1:1). Foram confeccionados compósitos experimentais (n=5) adicionados com carga nas concentrações de 0.01, 0.5, 2 e 10% em massa (p/p). A liberação da CHX foi avaliada in vitro em uma solução neutra (pH 7, 50mm) a 37 oC, por 366 horas. A quantificação de CHX foi avaliada por espectrofotometria de UV (λ=255 nm). A formação de nanocompósitos foi avaliada por meio das metodologias Microscopia Eletrônica de Transmissão (MET) e Difração de Raio-X (DRX). Foi observada uma liberação de fármaco constante em todos os grupos analisados, de 0 a 366 horas. Ao atingir 366 horas, o grupo adicionado com 0,01% de carga apresentou 0.126 g.L-1 de liberação de CHX, o grupo com 0.5% apresentou 0.139 g.L-1, o grupo com 2% apresentou 0.150 g.L-1 e o grupo com 10% apresentou 0.151 g.L-1. Observou-se por meio do DRX e MET que houve intercalação entre a MMT (adicionada com CHX) e a matriz polimérica, em todos os grupos avaliados. Concluiu-se que houve a formação de nanocompósitos e que os mesmos promoveram constante liberação de CHX entre 0 a 366 horas. Esses resultados evidenciaram um forte potencial no desenvolvimento de nanocompósitos contendo fármaco antimicrobiano para aplicação odontológica.
Chemical and mechanical properties of experimental dental composites as a function of formulation and postcuring thermal treatment
2018 - ESTEVES, RENATA A.; BOARO, LETICIA C.C.; GONÇALVES, FLAVIA; CAMPOS, LUIZA M.P.; SILVA, CECY M.; RODRIGUES-FILHO, LEONARDO E.
This study evaluated the influence of formulation and thermal treatment on the degree of conversion, fracture toughness, flexural strength, and elasticmodulus of experimental composites. Six composites were analyzed at BisGMA: TEGDMAmolar ratios of 1 : 1 and 7 : 3 with filler at 30, 50, and 70wt%.The degree of conversionwas analyzed by Fourier transforminfrared spectroscopy, fracture toughness was measured using the single-edge notched beam, and flexural strength and elastic modulus were measured with the 3-point bend test. For all tests, one-half of the specimens received thermal treatment at 170∘C for 10 min. Data were analyzed by the Kruskal-Wallis or ANOVA/Tukey’s test (𝛼 = 5%).The 1 : 1 BisGMA : TEGDMA ratio showed higher properties than the 7 : 3 ratio. Although the material with 70% filler had a conversion lower than the one with 50%, it showed higher mechanical properties.The thermal treatment improved all properties in all materials. Therefore, the use of an equimolar ratio of BisGMA: TEGDMA can be paired with 70 wt% filler to design dental composites that possess increased advantageous physical and chemical properties. Furthermore, the simple and low-cost method of thermal treatment proposed for use in clinical dentistry has been shown to effectively improve the properties of all evaluated materials.
Antibacterial resin-based composite containing chlorhexidine for dental applications
2019 - BOARO, LETICIA C.C.; CAMPOS, LUIZA M.; VARCA, GUSTAVO H.C.; SANTOS, TAMIRIS M.R. dos; MARQUES, PAMELA A.; SUGII, MARI M.; SALDANHA, NATHALIA R.; COGO-MULLER, KARINA; BRANDT, WILLIAM C.; BRAGA, ROBERTO R.; PARRA, DUCLERC F.
Objeticve. The aim of this study was to develop a composite material with antibacterial activ-ity using MMT loaded with clorhexidine (CHX). For that it was used a BisGMA/TEGDMAmatrix and added low concentration of MMT/CHX. The aim was to evaluate the drug releasecapacity of MMT, and not to provide reinforcement.Methods. Six experimental composites were made with organic matrix of BisGMA/TEGDMAin equal proportions by weight. The composites received organophlizated montmorillonitewith or without CHX. The concentrations were 2,5; 5 or 10% by weight. Degree of conversion(DC) was evaluated using FTIR (peak 6165 cm-1; n = 5). Specimens for flexural properties(10×2×1 mm) were immediate tested (24h). Elastic modulus(E) and flexural strength (FS)was measured using the three point bending test (n = 10). Inibition halo was used to test theantibacterial activity against Staphylococcus aureus, Streptococcus mutans, and Porphyromonasgingivalis (n = 5 for each bacteria). The inhibition of biofilm formation (BF) was evaluated byinserting polymerized disc of composite in to a culture media colonized with Streptococcusmutans (n = 10). The release of CHX was measured using ultraviolet (255 nm) for 10 days(n = 5). The data of degree of conversion was analysed using Kruskal–Wallis/ Mann–Whitney,and the other variables using two-way ANOVA/Tukey, always considering a global level ofsignificance of 5%.Results. DC ranged from 71% to 74%. E ranged from 5.7 to 8.1 GPa. FS ranged from 61.4 to74.7 MPa. There were no statistical differences among the groups for all the variables. Forthe three bacteria tested the composites with CHX loaded presented inhibition of growthfor all concentration, except for 2,5% that did not inihibited the growth of P. gingivalis. BFwas lower for the groups with 10% MMT/CHX, all groups presented BF, even those withoutCHX loaded. All concentrations presented release off CHX during all the 28 days analyzed. Conclusions. Within the limitation of this study it can be concluded that: all concentrations tested presented release of CHX and reduced BF. All concentration presented antibacterial activity for the three bacteria tested, except for 2,5% that did not inhibit the growth of P. gingivalis. The presence of MMT with CHX loaded did not interfere in the properties evaluated.
Avaliação das propriedades térmicas de compósitos experimentais odontológicos a base de BISGMA e TEGDMA utilizando como carga nanopartículas de MMT e MMT/AMX
2018 - SANTOS, T.M.R.; SANTOS, M.J.; CAMPOS, L.M.P.; PARRA, D.F.
O objetivo do presente estudo foi identificar a influência da nanopartícula de Montmorillonita (MMT) carregada com amoxicilina (AMX) nas propriedades térmica de um compósito experimental odontológica a base de BISGMA e TEGDMA. Foram feitos ensaios individuais dos componentes da matriz polimérica odontológica, do compósito com de MMT e do compósito com MMT/Amoxicilina. Primeiramente foi feito um sol de MMT+AMX com 9 partes de MMT para 1 parte de AMX. Foram confeccionados compósitos com 9% de MMT e 10% de MMT/AMX e também um grupo controle sem carga para comparações. Observou-se a interação dos componentes da matriz odontológica entre si, da matriz carregada com o sol de MMT/AMX e da matriz utilizando somente a MMT como carga. As caracterizações dos compósitos foram realizadas por meio das seguintes técnicas: Análise de Termogravimetria (TGA), Calorimetria exploratória diferencial (DSC) e Espectroscopia de Infravermelho com transformada de Fourier (FTIR) dos compósitos. A faixa de temperatura na análise de TGA foi de 25 - 600 ºC com taxa de aquecimento de 10 ºC min-1, em atmosfera de nitrogênio. A faixa de temperatura do DSC foi de 25 - 550ºC, em atmosfera de nitrogênio e a análise de FTIR foi feita por transmitância dos compósitos e dos pós individualizados. Observaram-se por meio do TGA todos os eventos de decomposição dos componentes da matriz polimérica, os mesmos se degradaram abaixo de 500ºC. Já com todos os componentes devidamente homogeneizados. A temperatura de degradação total chegou a 510 ºC, já para o grupo com MMT e MMT/AMX em sua composição, a temperatura de degradação ultrapassou os 520 ºC. Foi observado que a MMT interfere na resistência térmica do compósito e a AMX não afetou a estabilidade que a MMT trouxe para o compósito. Por meio da análise de FTIR foi possível identificar a presença dos componentes, tanto para a matriz, quanto para as cargas.
Síntese de nanopartículas de prata funcionalizadas com BisGMA e TEGDMA para uso odontológico
2018 - SANTOS, M.J.; SANTOS, T.M.R.; OLIVEIRA, C.B.; CAMPOS, L.M.P.; PARRA, D.F.
A resina composta permanece como material de eleição no tratamento das lesões cariosas. Entretanto, uma maior formação de biofilme bacteriano ocorre na superfície das restaurações realizadas com esse material quando comparadas ao amálgama dental e cimento de ionômero de vidro, por exemplo. O BisGMA (metacrilato de glicida do Bisfenol A) e o TEGDMA (dimetacrilato de trietilenoglicol) são os dois monômeros mais comumente utilizados na composição da fração orgânica da resina composta. A incorporação de partículas de carga nessa matriz é responsável por conferir melhores propriedades físicas e mecânicas e a incorporação de nanopartículas de prata tem o intuito de conferir ainda atividade antimicrobiana. Para que não haja então prejuízo das propriedades do material, essas partículas devem ser funcionalizadas. Neste trabalho, nanopartículas de prata foram sintetizadas e funcionalizadas em BisGMA e TEGDMA. A caracterização das nanopartículas foi feita através das técnicas de UV-Vis, DLS, MEV-EDS, TEM e teste de atividade bactericida. As análises evidenciam a síntese efetiva de partículas de prata na escala nanométrica com atividade antimicrobiana para incorporação em resinas compostas odontológicas.
Liberação da amoxicilina em compósitos odontológicos com base no índice de adsorção de fármaco na nanopartícula
2018 - SANTOS, T.; CAMPOS, L.; SANTOS, M.; PARRA, D.
Este estudo tem como objetivo avaliar a adsorção da Amoxicilina na nanopartícula de Montmorilonita (MMT) e sua liberação em compósitos restauradores finais, para aplicações odontológicas. A adsorção da amoxicilina na nanopartícula de MMT foi feita em uma solução de água milli-Q, com agitação constante de 48 horas. Foram feitas medições de 2 em 2 horas. A partir do ensaio de dessorção, foi possível observar em porcentagem o valor de carregamento de fármaco na argila. Após avaliação desse estudo, foi realizada a incorporação da amoxicilna na nano argila por processo de sonicação e secagem em estufa. Para avaliação da liberação de fármaco, foram elaborados corpos de prova com o composto argila/fármaco em uma matriz polimérica a base de BisGMA e TEGDMA para ensaio de liberação de fármaco. Os resultados desse estudo evidenciam a capacidade de absorção real da Amoxicilina na nanopartícula de MMT, e assim tornando possível observar o potencial de liberação de fármaco da matriz polimérica.
Conversion of endodontic sealer modified with nanoparticles carrying antibacterial drugs
2017 - SANCHES, L.K.F.; CAMPOS, L.M.P.; PARRA, D.F.; BRAGA, R.R.; SANTOS, M.; BOARO, L.C.C.
Purpose/aim: The aim of this study was to evaluate the polymeric conversion of a commercial endodontic sealer modified with montmorillonite nanoparticles carrying to different antibacterial drugs: clorhexidine (CHX) and metronidazole (MET). Materials and methods: The sealer used was AH Plus sealer, and 5% in weight was added of the nanoparticles carrying one of the drugs CHX or MET. Cylindrical specimens were made with 5 mm diameter and 1 mm thick (n = 5). The degree of conversion (DC) was determined using near FTIR. DC was evaluated using the absorption peak at 4529 cm−1 that decrease during polymerization, and the absorption peak at 4623 cm−1 which is unaltered as normalization. The measurements were obtained for each sample immediately, 4 h and 24 h after mixing the two pastes of the sealer. A group with no modification by the nanoparticle was added as a control. The data was analyzed using one-way ANOVA/Tukey (α = 5%). Results: Results are presented in Table 1. Table 1. Means (SD) for degree of conversion (%) at 4 and 24 h. No statistical difference was presented among groups for neither periods of evaluation. Drug DC (%) 4 h 24 h Control 35 (11) A 68 (8) A CHX 31 (11) A 81 (11) A MET 38 (6) A 77 (14) A Conclusions: Within the limitations of this study it can be concluded that addition of the nanoparticle carrying both drug did not influence the polymerization of the sealer.
Antibacterial activity of endodontic sealer modified with nanoparticles
2017 - SILVA, L.T.S.; COGO-MULLER, K.; BRANDT, W.C.; CAMPOS, L.M.P.; PARRA, D.F.; SANTOS, M.; BOARO, L.C.C.
Purpose/aim: The aim of this study was to evaluate the antibacterial activity of a commercial endodontic sealer modified with montmorillonite nanoparticles carrying to different drugs: clorhexidine (CHX) and metronidazole (MET). Materials and methods: The sealer used was AH Plus sealer, and 5% in weight was added of the nanoparticles carrying one of the drugs CHX or MET. Cylindrical specimens were made with 5 mm diameter and 1 mm thick (n = 5). The antibacterial activity was evaluated by the inhibition halo test. This method was conducted according to Clinical Standard Laboratory Institute M2-A8 protocol, with some modifications (CLSI, 2003). The bacteria selected were the E. Fecallis which is the most frequently bacteria found in recidivate apical infection. Discs specimens were positioned over the agar and plates were incubated in the appropriate conditions for 48 h. After this period, inhibition zones were measured using a calliper rule. A group with no modification by the nanoparticle was added as a control. The data was analyzed using Mann–Whitney (alpha = 5%). Results: Results are presented in Table 1. For the control group no inhibition zone was formed, so the statistical analyze was performed only between the experimental groups. Table 1. Means (SD) for inhibition halo (mm). No statistical difference was presented between the drugs. Drug Inhibition halo (mm) Control 0 CHX 4.8 (1.4) A MET 4.0 (1.6) A Conclusions: Within the limitations of this study it can be concluded that the addition of the nanoparticle carrying both drugs added an antibacterial activity that was not found in the commercial sealer.
Nfluence of radiation on the thermal and mechanical properties of BISGMA / TEGDMA based nanocomposites using pre-irradiated MMT nanoparticles as filler
2017 - SANTOS, TAMIRIS M.R.; CAMPOS, LUIZA M.P.; SANTOS, MARIANA de J.; BOARO, LETICIA C.; PARRA, DUCLERC F.
In the present study was observed the influence of gamma radiation in thermal and mechanical properties of the experimental dental composites based on BISGMA/TEGDMA filled with pre-irradiated MMT nanoparticles (Cloisite® 20A). MMT nanoparticle was pre-irradiated at doses of 10, 15 and 70 kGy. As a control group MMT nanoparticle was added in the polymeric matrix without pre-irradiation. Four formulations of experimental nanocomposites were studied all with 50% wt of filler. The characterization of the experimental composites was performed by means of the following techniques: Thermogravimetry Analysis (TGA), Elastic Modulus and Flexural Strength. It was observed that the group filled with pre-irradiated nanoparticles at dose of 70 kGy showed a delay in the decomposition temperature when compared to the control group. For elastic modulus the results showed a proportional increase related to the dose of radiation applied in the MMT nanoparticle. Regarding flexural strength, the groups filled with pre–irradiated nanoparticles and the control group presented similar results.