Desempenho adesivo de sistemas de união à dentina aplicados in vivo e in vitro: efeito da pressão intrapulpar e profundidade dentinária

O objetivo do presente estudo foi investigar a influência da pressão intrapulpar e da profundidade dentinária sobre o desempenho adesivo de dois agentes de união à dentina, Single Bond (3M ESPE, St. Paul, MN, EUA) e Clearfil SE Bond (Kuraray, Tokyo, Japão), aplicados in vitro e in vivo. Quarenta e oito prémolares superiores hígidos foram selecionados e os pares pertencentes aos mesmos pacientes foram aleatoriamente distribuídos em 4 grupos experimentais de acordo com o sistema adesivo e a pressão intrapulpar, presente ou ausente. Dos dentes pertencentes ao mesmo par, um foi tratado in vivo e o outro in vitro. A ausência ou presença de pressão intra-pulpar foi determinada in vivo pelo uso de anestésicos locais com ou sem vasoconstritor, respectivamente. In vitro, os dentes foram mantidos sob pressão hidrostática de 15 cm de água por 24 horas. Cavidades de classe I foram preparadas e os sistemas adesivos aplicados de acordo com a recomendação dos fabricantes, seguidos da restauração incremental em resina composta. Para os dentes tratados in vitro, os mesmos procedimentos restauradores foram realizados após 6 meses de armazenagem em solução contendo timol 0,1%. Espécimes com área de secção transversal de 1 mm2 foram obtidos e submetidos ao ensaio mecânico de microtração. In vivo, ambos os sistemas adesivos apresentaram desempenho adesivo comparável, enquanto in vitro, o sistema Single Bond foi superior ao sistema Clearfil SE Bond. Esse último não foi influenciado por nenhuma das variáveis estabelecidas no estudo, ou seja, aplicação in vitro ou in vitro, presença de pressão intrapulpar e profundidade em dentina. O sistema Single Bond aplicado sob pressão intrapulpar positiva sofreu variação significante de resistência de união em função da profundidade da dentina, ou seja, em dentina profunda seu desempenho adesivo... (Resumo completo, clicar acesso eletrônico abaixo)

Rhizospheric streptomycetes as potential biocontrol agents of Fusarium and Armillaria pine rot and as PGPR for Pinus taeda

Pinus taeda is one of the main timber trees in Brazil, occupying 1.8 million ha with an annual productivity of 25-30 m(3) ha(-1). Another important species is Araucaria angustifolia, belonging to the fragile Rainforest biome, which for decades has been a major source of timber in Brazil. Some diseases that affect the roots and/or the stem of these trees and cause "damping-off" of the seedlings, with economic and environmental losses for the forest sector, are caused by the plant pathogenic fungi Fusarium sp. or Armillaria sp. This research project intended to isolate actinobacteria from the Araucaria rhizosphere, which present an antagonistic effect against these fungi. After the selection of the best pathogen inhibitors, morphologic characteristics, enzyme production, and their effect on the growth of Pinus taeda were studied. The actinobacteria were tested for their antagonistic capacity against Fusarium sp. in Petri plates with PDA as substrate. The inhibition zone was measured after 3, 5, 7, and 10 days. Of all the isolates tested, only two of them maintained inhibition zones up to 4 mm for 10 days. The inhibition of Armillaria sp. was tested in liquid medium and also in Petri dishes through the evaluation of the number of the fungal rhizomorphs in dual culture with the actinobacteria. It was found that all five isolates were able to inhibit the rhizomorph production, with the best performance of the isolate A43, which was capable of inhibiting both fungi, Fusarium and Armillaria. In a greenhouse experiment, the effect of five isolates on the growth of Pinus taeda seedlings was tested. Plant height, stem diameter, root and shoot dry matter were determined. The Streptomyces isolate A43 doubled plant growth. These results may lead to the development of new technologies in the identification of still unknown bacterial metabolites and new management techniques to control forest plant diseases.

Effectiveness of therapeutic agents in disease treatment in Piaractus mesopotamicus

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Hydroxyquinoline derived vanadium(IV and V) and copper(II) complexes as potential anti-tuberculosis and anti-tumor agents

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cardiovascular Complications following Chronic Treatment with Cocaine and Testosterone in Adolescent Rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of light-curing on the antibacterial activity of dentin bonding agents

Aim: This study evaluated the effect of light-activation on the antibacterial activity of dentin bonding systems. Methods: Inocula of Streptococcus mutans and Lactobacillus casei cultures were spread on the surface of BHI agar and the materials were applied and subjected or not to light-activation. Zones of bacterial growth inhibition around the discs were measured. Results: Excite, Single Bond and the bond of Clearfil SE Bond (SE) and Clearfil Protect Bond (CP) did not show any antibacterial activity. The strongest inhibitory activity was observed for the primers of CP and Prompt (PR) against S. mutans and the primers of SE and PB against L. casei. Conclusion: Light-activation significantly reduced or suppressed the antibacterial activity of the initially active uncured dentin bonding systems

Correlation between pH and surface structural changes on human enamel submitted to different tooth whitening agents

The intense valuation of an esthetic pleasant smile guided the dentistry to bleached tooth due the popularity of whitening treatments. The consequence of it is an increasing interest in searching the effect of peroxides in hard dental tissues. The aim of this work was to analyze qualitatively in vitro the human enamel after three different bleaching treatments: Opalescence PF 10%, White Class 7.5% and Opalescence Xtra Boost 38%, correlating the structural changes in the surface of the enamel with its respective pH. A total of 40 sound human pre-molars were randomly divided into four groups of 10 elements, which had been immersed in artificial saliva during all the experiment. Bleaching protocols followed the recommendations of the respective manufacturers. Each bleached sample and control group were submitted to a scanning electronic microscopy analysis and compared with one another. Bleaching agents used in this experiment had modified the morphologic aspect of the surface of the dental enamel; however, it did not have correlation between the degrees of severity of the alterations and pH. There is a correlation between hydrogen peroxide concentration and changes in the enamel, where G4 showed more severe alterations, followed for G3 and G2.

Effect of staining agents on color change of composites

Composite resins are materials that can present color changing when exposed to pigments. Objective: The aim of this study was to evaluate, in vitro, the color changing of composites after immersion in different substances for different periods. Material and methods: Two microhybrid composite resins: Charisma (Heraeus – Kulzer) and Opallis (FGM) were used. Red wine and acai pulp were also used as immersion medium. For this study, 32 specimens with 10 mm of diameter and 2 mm of thickness were used, divided into 4 groups: Group 1 – Opallis composite immersed in red wine solution; Group 2 – Opallis composite immersed in acai berry pulp solution; Group 3 – Charisma composite immersed in red wine solution; Group 4 – Charisma composite immersed in acai berry pulp solution. The specimens were evaluated in the following time periods: T0 – baseline, T1 – 24 hours, T2 – 48 hours, T3 – 72 hours and T4 – 96 hours. For the assessment of staining, a spectrophotometer for colorimetry was used (Color Guide 45 / 0, PCB 6807 BYK-Gardner Gerestsried GmBH, Germany), and the values obtained were transferred to a computer and recorded according to CIELAB system. Results: The data were evaluated using Kruskal- Wallis non-parametric tests with the following mean values for the immersion periods of 24, 48, 72 and 96 hours, respectively: G1 – 7.35, 7.84, 9.04,10.48; G2 – 2.92, 4.15, 4.30, 4.64; G3 – 3.14, 7.35, 8.13, 8.43, G4 – 4.49, 5.99, 6.92, 6.76. Conclusion: Red wine showed a higher tendency toward altering the composite color than acai berry pulp. In addition, no significant difference was found concerning to the behavior of the two composite resins. Concerning to the immersion time periods, significant differences were only observed among the groups in the 24 hour time period.

Marginal adaptation of Class V restorations with current generation dentin-bonding agents: effect of different dentin surface treatments.

This study sought to assess the use of chlorhexidine with several excipients as a dentin surface treatment and its effect on marginal adaptation of class V restorations with current-generation dentin bonding agents. A total of 120 human third molars were selected and allocated into 12 groups, with standardized buccal class V restorations randomly divided into preconditioned dentin rinsed with: water; water + chlorhexidine; ethanol; or ethanol + chlorhexidine. After rinsing of dentin (previously conditioned with 35% phosphoric acid) with the test solutions, the Adper single bond 2, prime and bond 2.1, and Excite bonding systems were applied randomly. Restorations were performed with FiltekTM Z350 XT composite resin. The resulting specimens were subjected to thermal and mechanical load cycling. Quantitative analysis of marginal adaptation was performed on epoxy replicas by means of scanning electron microscopy. Results were assessed by means of the Kruskal-Wallis test (percentages of continuous margins) and Wilcoxon test (differences between percentages of continuous margins before and after thermal cycling and mechanical loading), at a significance level of p < 0.05. Outcomes in the chlorhexidine-treated groups were not superior to those obtained with other treatments.

In vitro study of staining agents effects on optical properties of esthetic restorative materials

The authors have studied the effect of four staining agents on the optical properties of esthetic restorative materials through translucency tests. Two commercial brands of composite resins were used: Point 4 (Kerr) and Charisma (Heraeus-Kulzer). The liquids tested were: wine, cola, chlorhexidine solution and nicotine solution. The translucency was measured at different periods of time: P0 – before immersion (baseline), P1 - 1 h after immersion, P2 - 2 h after immersion and successively, P3 – 24 h after immersion up to a period of 7 weeks. ANOVA statistical analysis was applied to the data (p < 0.05). The results lead to the following conclusions: (1) Composite resins submitted to the tested immersion mediums were stained, (2) the lower percentage of translucency was observed for nicotine containing solution, (3) The percentage of translucency decreased with the period of immersion.

Stress vulnerability during adolescence

Objective: This study investigated the physiological and somatic changes evoked by daily exposure to the same type of stressor (homotypic) or different aversive stressor stimuli (heterotypic) in adolescent and adult rats, with a focus on cardiovascular function. The long-term effects of stress exposure during adolescence were also investigated longitudinally. Methods: Male Wistar rats were exposed to repeated restraint stress (RRS, homotypic) or chronic variable stress (CVS, heterotypic). Results: Adrenal hypertrophy, thymus involution, and elevated plasma glucocorticoid were observed only in adolescent animals, whereas reduction in body weight was caused by both stress regimens in adults. CVS increased mean arterial pressure (adolescent: p = .001; adult: p = .005) and heart rate (HR; adolescent: p = .020; adult: p = .011) regardless of the age, whereas RRS increased blood pressure selectively in adults (p = .001). Rest tachycardia evoked by CVS was associated with increased cardiac sympathetic activity in adults, whereas a decreased cardiac parasympathetic activity was observed in adolescent animals. Changes in cardiovascular function and cardiac autonomic activity evoked by both CVS and RRS were followed by alterations in baroreflex activity and vascular reactivity to vasoconstrictor and vasodilator agents in adolescent adult animals. Except for the circulating glucocorticoid change, all alterations observed during adolescence were reversed in adulthood. Conclusions: These findings suggest a stress vulnerability of adolescents to somatic and neuroendocrine effects regardless of stress regimen. Our results indicated an age-stress type-specific influence in stress-evoked cardiovascular/autonomic changes. Data suggest minimal consequences in adulthood of stress during adolescence.

Compressive strength and setting time of MTA and portland cement associated with different radiopacifying agents

The aim of this study was to evaluate the compressive strength and setting time of MTA and Portland cement (PC) associated with bismuth oxide (BO), zirconium oxide (ZO), calcium tungstate (CT), and strontium carbonate (SC). Methods. For the compressive strength test, specimens were evaluated in an EMIC DL 2000 apparatus at 0.5 mm/min speed. For evaluation of setting time, each material was analyzed using Gilmore-type needles. The statistical analysis was performed with ANOVA and the Tukey tests, at 5% significance. Results. After 24 hours, the highest values were found for PC and PC + ZO. At 21 days, PC + BO showed the lowest compressive strength among all the groups. The initial setting time was greater for PC. The final setting time was greater for PC and PC + CT, and MTA had the lowest among the evaluated materials (< 0.05). Conclusion. The results showed that all radiopacifying agents tested may potentially be used in association with PC to replace BO.

Ph and antimicrobial activity of portland cement associated with different radiopacifying agents

The aim of this study was to evaluate the antimicrobial activity and pH changes induced by Portland cement (PC) alone and in association with radiopacifiers. Methods. The materials tested were pure PC, PC + bismuth oxide, PC + zirconium oxide, PC + calcium tungstate, and zinc oxide and eugenol cement (ZOE). Antimicrobial activity was evaluated by agar diffusion test using the following strains: Micrococcus luteus, Streptococcus mutans, Enterococcus faecalis, Pseudomonas aeruginosa, and Candida albicans. After 24 hours of incubation at 37°C, inhibition of bacterial growth was observed and measured. For pH analysis, material samples (n=10) were placed in polyethylene tubes and immersed in 10 mL of distilled water. After 12, 24, 48, and 72 hours, the pH of the solutions was determined using a pH meter. Results. All microbial species were inhibited by the cements evaluated. All materials composed of PC with radiopacifying agents promoted pH increase similar to pure Portland cement. ZOE had the lowest pH values throughout all experimental periods. Conclusions. All Portland cement-based materials with the addition of different radiopacifiers (bismuth oxide, calcium tungstate, and zirconium oxide) presented antimicrobial activity and pH similar to pure Portland cement.

Impact of chemical agents for surface treatments on microhardness and flexural strength of root dentin

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)