Is it necessary to pre-treat Dentine before GIC Restorations? Evidence from an in Vitro Study / É necessário pré tratar a dentina antes das restaurações de CIV? Evidência de um estudo in vitro

ABSTRACT The aim of this study was to assess the influence of differentpretreatmentapproaches on glass ionomer cement (GIC)bond strength (BS) to dentine. Sixty bovine incisors wereallocated into six groups according to substrate - sound orcariesaffecteddentine; and substrate pretreatmentapproach -no conditioning (control), polyacrylic acid for 10 s andphosphoric acid for 7 s. Teeth in the cariesaffecteddentinegroup were previously submitted to cariogenic pHcyclingchallenge. After dentine pretreatment,according to experi mentalgroups, polyethylene tubes were placed on flat dentinesurfaces and filled with GIC. Teeth were stored in distilledwater for 24 h at 37 °C and then submitted to microshear test(0.5 mm/min). Failure pattern analysis was performed understereomicroscope (400x). Data were analysed using twowayANOVA and Tukey's test (α=5%). Statistically significantdifferences were found for the pretreatmentapproach,regardless of substrate (p<0.001). The polyacrylic acid groupand control group had similar BS values, and were both betterthan the phosphoric acid group. In general, GIC had betterbonding performance in sound dentine than in cariesaffecteddentine. In conclusion, dentine pretreatmentwith polyacrylicacid did not improve the performance of GIC restoration onclinically relevant substrates.

RESUMO O objetivo deste estudo foi avaliar a influência de diferentesprétratamentosna resistência de união (RU) de cimentos deionômero de vidro (CIV) a dentina. Sessenta incisivos bovinosforam alocados em 6 grupos de acordo com o substrato -hígido ou cariado; e com a abordagem de prétratamento-sem condicionamento (controle), ácido poliacrílico por 10 s, eácido fosfórico por 7 s. Os dentes pertencentes aos grupos dedentina cariada foram previamente submetidos ao desafiocariogênico por meio da ciclagem de pH. Após o prétratamentoda dentina, de acordo com os grupos experimentais,tubos de polietileno foram colocados sobre superfícies planas dedentina e preenchidos com CIV. Os dentes foram armazenadosem água destilada por 24 h a 37°C e então submetidos ao testede microcisalhamento (0,5 mm/min). A análise do padrão defratura foi realizada em estereomicroscópio (400x). Os dadosobtidos foram analisados usando ANOVA de dois fatores e testede Tukey (α=5%). Diferença estatisticamente significante foiencontrada para as diferentes abordagens de prétratamento,independente do substrato (pp<0,001). Aplicação de ácidopoliacrílico resultou em valores de RU similares aos do grupocontrole. Entretanto, ambos os grupos mostraram um melhordesempenho quando comparado a aplicação de ácidofosfórico. De forma geral, CIV apresentou melho5 desempenhoadesivo em dentina sadia quando comparada a dentinacariada. Em conclusão, o prétratamentoem dentina comácido poliacrílico não melhora o desempenho das restauraçõesde CIV em substratos clinicamente relevantes.

Influence of resin-modified glass ionomer and topical fluoride on levels of Streptococcus mutans in saliva and biofilm adjacent to metallic brackets

Abstract Decalcification of enamel during fixed orthodontic appliance treatment remains a problem. White spot lesions are observed in nearly 50% of patients undergoing orthodontic treatment. The use of fluoride-containing orthodontic materials has shown inconclusive results on their ability to reduce decalcification. The aims of this investigation were to compare the levels of Streptococcus mutans (SM) in saliva and biofilm adjacent to orthodontic brackets retained with a resin-modified glass ionomer cement (RMGIC) (Fuji ORTHO LC) and a light cured composite resin (Transbond XT), and to analyze the influence of topical application of the 1.23% acidulated phosphate fluoride (APF) on SM counts. In a parallel study design, two groups (n=14/15) were used with random allocation and high salivary SM counts before treatment. Biofilm was collected from areas adjacent to the brackets on teeth 13, 22, 33, and 41. Both saliva and biofilm were collected on the 7th, 21st, 35th, and 49th days after appliance placement. Topical fluoride application was carried out on the 35th day. Bonding with RMGIC did not alter SM counts in saliva or biofilm adjacent to the brackets. On the other hand, the biofilm adjacent to brackets retained with composite resin showed a significant increase in SM counts along the trial period. Topical application of 1.23% APF did not reduce salivary or biofilm SM counts regardless of the bonding material. In conclusion, fluoride topical application did not show efficacy in reducing SM. The use of RMGIC as bonding materials allowed a better control of SM cfu counts in dental biofilm hindering the significant increase of these microorganisms along the trial period, which was observed in the biofilm adjacent to the composite material.

Development of a novel resin with antimicrobial properties for dental application

The adhesion of biofilm on dental prostheses is a prerequisite for the occurrence of oral diseases. Objective: To assess the antimicrobial activity and the mechanical properties of an acrylic resin embedded with nanostructured silver vanadate (β-AgVO3). Material and Methods: The minimum inhibitory concentration (MIC) of β-AgVO3 was studied in relation to the species Staphylococcus aureus ATCC 25923, Streptococcus mutans ATCC 25175, Pseudomonas aeruginosa ATCC 27853, and Candida albicans ATCC 10231. The halo zone of inhibition method was performed in triplicate to determine the inhibitory effect of the modified self-curing acrylic resin Dencor Lay - Clássico®. The surface hardness and compressive strength were examined. The specimens were prepared according to the percentage of β-AgVO3 (0%-control, 0.5%, 1%, 2.5%, 5%, and 10%), with a sample size of 9x2 mm for surface hardness and antimicrobial activity tests, and 8x4 mm for the compression test. The values of the microbiologic analysis were compared and evaluated using the Kruskal-Wallis test (α=0.05); the mechanical analysis used the Shapiro-Wilk's tests, Levene's test, ANOVA (one-way), and Tukey's test (α=0.05). Results: The addition of 10% β-AgVO3 promoted antimicrobial activity against all strains. The antimicrobial effect was observed at a minimum concentration of 1% for P. aeruginosa, 2.5% for S. aureus, 5% for C. albicans, and 10% for S. mutans. Surface hardness and compressive strength increased significantly with the addition of 0.5% β-AgVO3 (p<0.05). Higher rates of the nanomaterial did not alter the mechanical properties of the resin in comparison with the control group (p>0.05). Conclusions: The incorporation of β-AgVO3 has the potential to promote antimicrobial activity in the acrylic resin. At reduced rates, it improves the mechanical properties, and, at higher rates, it does not promote changes in the control. .

Mechanical and Biological Properties of Acrylic Resins Manipulated and Polished by Different Methods

This study evaluated the influence of the manipulation technique and polishing method on the flexural strength and cytotoxicity of acrylic resins. Two manipulation techniques and three polishing methods were used in the fabrication of acrylic plates that were divided into 6 groups (n=10). Groups MM, MC and MW: mass technique with mechanical polishing, chemical polishing and without polishing, respectively; and Groups SM, SC and SW: Saturation technique with mechanical polishing, chemical polishing and without polishing, respectively). Flexural strength was tested in a universal testing machine and the cytotoxicity assay used cell cultures (L-929) for periods of 24 h to 168 h. Flexural strength and cytotoxicity data were assessed using two-way and three-way ANOVA, respectively (α=0.05), followed by post hoc Bonferroni test for multiple comparisons. The effect of combinations of manipulation techniques and polishing methods on flexural strength showed significant differences only between Group SC and Groups MW, MM and MC (p<0.01). Cell viability ranged from 51% (3.9%) to 87,6% (3.2) in the 24-h time interval, and from 87.8% (5.0) to 95.7% (3.1%) in the 168-h time interval. With the increase of cell viability, from the third day (72 h), there was no significant difference among the groups, except between MM and SC (p<0.01) at 72 h. In conclusion, the manipulation technique and polishing method had more influence on the cytotoxicity than on flexural strength.

Este estudo avaliou a influência da técnica de manipulação e método de polimento sobre a resistência à flexão e citotoxicidade de resinas acrílicas. Duas técnicas de manipulação e três métodos de polimento foram usados na fabricação de placas de acrílico que foram divididas em 6 grupos (n=10). Grupos MM, MC e MW: técnica de massa com polimento mecânico, polimento químico e sem polimento, respectivamente; e Grupos SM, SC e SW: técnica de saturação com polimento mecânico, polimento químico e sem polimento, respectivamente. A resistência à flexão foi testada em uma máquina universal de ensaios e o ensaio de citotoxicidade foi realizada utilizando culturas de células (L929) para os períodos de 24 h a 168 h. Dados da resistência à flexão e de citotoxicidade foram avaliados usando ANOVA dois fatores e ANOVA três fatores, respectivamente (α=0,05), seguido pelo teste post hoc de Bonferroni para comparações múltiplas. O efeito das combinações de técnicas de manipulação e métodos de polimento na resistência à flexão mostraram diferenças significativas apenas entre Grupo SC e Grupos MW, MM e MC (p<0,01). A viabilidade celular variou de 51,0% (3,9%) para 87,6% (3,2%) no intervalo de tempo de 24 h, e de 87,8% (5,0%) para 95,7% (3,1%) no intervalo de tempo de 168 h. Com o aumento da viabilidade celular, a partir do terceiro dia (72 h), não houve diferença significativa entre os grupos, exceto entre MM e SC (p<0,01) em 72 h. Em conclusão, a técnica de manipulação e o método de polimento tiveram maior influência sobre a citotoxicidade do que sobre a resistência à flexão.

Effect of an acrylic resin combined with an antimicrobial polymer on biofilm formation

OBJECTIVES: The purpose of this study was to evaluate the antimicrobial activity of an acrylic resin combined with an antimicrobial polymer poly (2-tert-butylaminoethyl) methacrylate (PTBAEMA) to inhibit Staphylococcus aureus, Streptococcus mutans and Candida albicans biofilm formation. MATERIAL AND METHODS: Discs of a heat-polymerized acrylic resin were produced and divided according to PTBAEMA concentration: 0 (control), 10 and 25%. The specimens were inoculated (10(7) CFU/mL) and incubated at 37ºC for 48 h. After incubation, the wells were washed and each specimen was sonicated for 20 min. Replicate aliquots of resultant suspensions were plated at dilutions at 37ºC for 48 h. The number of colony-forming units (CFU) was counted and expressed as log (CFU+1)/mL and analyzed statistically with α=.05. RESULTS: The results showed that 25% PTBAEMA completely inhibited S. aureus and S. mutans biofilm formation. A significant reduction of log (CFU+1)/mL in count of S. aureus (control: 7.9±0.8A; 10%: 3.8±3.3B) and S. mutans (control: 7.5±0.7A; 10%: 5.1±2.7B) was observed for the group containing 10% PTBAEMA (Mann-Whitney, p<0.05). For C. albicans, differences were not significant among the groups (control: 6.6±0.2A; 10%: 6.6±0.4A; 25%: 6.4±0.1A), (Kruskal-Wallis, p>0.05, P=0.079). CONCLUSIONS: Acrylic resin combined with 10 and 25% of PTBAEMA showed significant antimicrobial activity against S. aureus and S. mutans biofilm, but it was inactive against the C. albicans biofilm.

Effect of renal embolization with trisacryl and PAVc

OBJECTIVES: Evaluate the degree of vascular occlusion, vascular recanalization, and necrosis of the vascular wall caused by polyvinyl alcohol-covered polyvinyl acetate (PVAc) particles compared to trisacryl particles after renal embolization. METHODS: Seventy-nine female albino New Zealand rabbits underwent arterial catheterization of the right kidney. Thirty-three animals were embolized with trisacryl particles, thirty-one with PVAc particles, and fifteen were kept as controls. Four animals were excluded (three trisacryl and one PVAc) due to early death. Five subgroups of six animals were created. The animals in the different groups were sacrificed either 48 hours, 5 days, 10 days, 30 days, or 90 days after embolization. The control group was divided into subgroups of three animals each and kept for the same periods of time. The kidneys were dyed with hematoxylin-eosin and Masson's trichrome and then examined using optical microscopy. RESULTS: There were significant differences in the degree of vascular occlusion caused by the trisacryl and the PVAc particles between the five-day and the ten-day groups. Additional differences were noted between the five-day and 48-hour groups in regard to the amount of necrosis. For both findings, the PVAc group members showed adequate tissue reaction (ischemia and volumetric reduction) and less recanalization than those treated with trisacryl. CONCLUSION: The use of PVAc as an embolization material exhibited an adequate tissue reaction (ischemia and volumetric reduction), more expressive vascular occlusion and necrosis, and less recanalization than the trisacryl material.

A study to evaluate the antimicrobial activity of feracrylum and its comparison with povidone-iodine.

Feracrylum, a water-soluble polymer of polyacrylic acid is known for its hemostatic property. Present work is an effort to evaluate its minimum inhibitory concentration (MIC) and compare it with the MIC of povidone-iodine. Ten different species of pathogenic microorganisms were selected, strains of which were obtained from Haffkine Institute. The organisms were maintained under appropriate culture media. The MIC of Freracrylum was determined by using tube culture method where its activity was compared against a standard antimicrobial agent providone-iodine. The study parameters showed that Feracrylum exhibits antimicrobial activity against a wide variety of microorganisms and its efficacy is comparable to that of povidone-iodine.

Avaliação da reação tecidual de uma resina termoplástica em tecido subcutâneo de ratos / Assessment of subcutaneous rat tissue reaction to a thermoplastic resin

A reação tecidual da resina tesmoplástica TAK Hydroplastic foi avaliada por meio da sua implantação em tecido subcutâneo de ratos nos períodos de observação de duas, três, seis e 12 semanas. A resina acrílica incolor termicamente ativada foi escolhida como Grupo Controle. No final de duas semanas o tecido subcutâneo dos ratos adjacentes aos corpos de prova do Grupo Controle e Experimental, exibiram uma reação inflamatória moderada que decresceu para leve no período de observação de 12 semanas, mostrando ser o TAK Hydroplastic, um material aceitável em testes de implantação subcutânea

Biocompatibilidade de resinas acrílicas termicamente ativadas (incolor e com pigmento rosa): teste biológico em tecido conjuntivo de ratos / Biocompatibility of acrylic resins activated by heat (uncolored and with rose pigment): biological test in connective tissue of rats

Testou-se a biocompatibilidade de discos de resinas acrílicas termicamente ativadas, incolor e com pigmento rosa, utilizadas na confecçäo de próteses, em tecido conjuntivo de 12 ratos, sacrificados com 7, 14, 21 e 28 dias de implantaçäo. Os materiais mostraram ser biocompatíveis ao tecido conjuntivo, podendo ser utilizados na intimidade dos tecidos. A resina incolor mostrou reaçäo mais favorável

Comparaçäo de métodos para determinaçäo de anticorpos para rubéola na fraçäo IgM: ultracentrifugaçäo em gradiente de sacarose e cromatografia em microcoluna de Sephacryl S-300 / Comparison of methods for rubella IgM antibody determination: sucrose density fractionation and microcolumn chromatography using Sephacryl S-300

Os métodos de ultracentrifugaçäo em gradiente de sacarose e cromatografía em microcolunas de Sephacryl S-300 foram comparados na pesquisa de anticorpos da classe IgM para rubéola. Após o fracionamento das imunoglobulinas, empregou-se a reaçäo de inibiçäo da hemaglutinaçäo para determinar os anticorpos das fraçöes. O uso de microcolunas representa uma metodologia simples e rápida, com resultados seguros entre as 1ª e 3ª semanas após o início da doença. Pela fácil execuçäo e baixo custo, pode ser aplicada na separaçäo de imunoglobulinas, encontrando uma ampla aplicaçäo no laboratório clínico para o estudo de diferentes agentes

Recubrimiento pelicular con una dispersión de resinas acrílicas / Pelicular recover with acrilic resin

El presente trabajo se realizó con el propósito de comprobar la conveniencia de la aplicación de resinas acrílicas en medio acuoso para recubrir tabletas, empleándose 2 tipos de tabletas, oblangos y ovaladas a los que se aplicaron 2 tipos de resinas acrílicas, una para cubierta entérica y otra para liberación a nivel del estómago ensayándose diversos espesores de película y cantidades diferentes de materiales hidrófilos de modo que se pudiera definir un menor tiempo de liberación acorde al pH del tracto gastrointestinal. La aplicación de las resinas acrílicas se efectuó empleando un bombo grageador piloto, al cual se adaptó un ventilador de aire frio, una secadora y una pistola de aire comprimido, con una sola tobesa manteniéndose, para la pulverización de las resinas, condiciones definidas de ángulo y velocidad de rodamiento de las tabletas, el ángulo de inclinación de la aguja inyectora y la temperatura de aire de secado. Las tabletas ovaladas fueron más fáciles de recubrir en tanto que los oblangas demandaron de una mayor velocidad de rodamiento para evitar que se pegasen entre si.