Analysis of Calcium and Phosphate Ion Extraction From Dental Enamel by Bleaching Gels Using Ion Chromatography, Micro-CT, and SEM.

OBJECTIVES: To evaluate the volume and depth of enamel loss promoted by 37.5% and 7.5% hydrogen peroxide (HP) gels, and quantify the loss of calcium (Ca) and phosphate (P) ions by using ion chromatography (IC) analysis after bleaching. METHODS: Sixty bovine enamel specimens were randomly divided into three groups: Control - no bleaching gel; HP37.5%, application of HP 37.5% for 45 minutes for 14 days; and HP7.5%, application of HP 7.5% for 3 applications of 8 minutes. The surface analysis (n=5) was performed using a scanning electron microscope (SEM) and dispersive energy system (EDS) to calcium and phosphorus dosage. The micro-CT was used for the enamel loss analysis (n=5). IC was used to analyze extracted Ca and P (n=10). Data were analyzed by one-way ANOVA and two-way repeated measures ANOVA, followed by Tukey and Dunnett's tests (α=0.05). RESULTS: Significantly higher volume and depth of enamel loss were found for bleached groups compared with the control group. HP7.5% had significantly higher enamel change than HP37.5%. SEM showed higher enamel porosity for HP37.5% and HP7.5% compared to control. The IC demonstrated a significant increase of Ca incorporated into the gel, however, only HP7.5% had a higher P presence than the control group. The HP7.5% showed higher Ca and P ion exchange than HP37.5% (p<0.001). CONCLUSION: HP37.5% and HP7.5%, caused enamel mineral changes compared with the control group. The IC method was demonstrated to be an effective methodology for detecting enamel mineral loss by the bleaching gel.

Use of Computerized Microtomography, Energy Dispersive Spectroscopy, Scanning Electron Microscopy, and Atomic Force Microscopy to Monitor Effects of Adding Calcium to Bleaching Gels.

OBJECTIVES: The aim of this study was to evaluate the mineral content, expressed by calcium (Ca) and phosphate (P), in dental enamel exposed to bleaching agents using micro-computed tomography (micro-CT), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM). METHODS: Sixty bovine dental enamel specimens were randomly divided into three groups (n=20): HP35ca (bleached using 35% hydrogen peroxide with Ca); HP35wca (bleached using 35% hydrogen peroxide without Ca); and control (without bleaching). Five specimens from each group were used for SEM and EDS analyses, 10 specimens were used for AFM analysis, and the remaining five specimens were used for micro-CT analysis. The pH of the gels was measured using a pH meter. The EDS and micro-CT data were analyzed using one-way ANOVA and Pearson's correlation test. The AFM data were analyzed using one-way ANOVA (α=0.05). RESULTS: The weight percentages of Ca and P obtained using EDS were similar between the bleached and control groups. Small, superficial changes were observed by SEM in the HP35wca group. The HP35ca group showed similar patterns to the control group. AFM results showed no significant changes in the enamel roughness in any of the tested groups. No significant difference in the volume or depth of structural enamel loss was found between gels with and without Ca. No mineral loss was observed in the dentin substrate. The EDS and micro-CT analysis data exhibited a high correlation (p<0.001). CONCLUSION: The addition of Ca to the bleaching gel had no beneficial effect on the bleached tooth enamel in terms of composition, mineral loss, and surface roughness. Micro-CT results exhibited a high correlation with the EDS results.

Atividade antimicrobiana de extratos etanólicos de Peperomia pellucida e Portulaca pilosa / Antimicrobial activity of ethanol extracts of Peperomia pellucida and Portulaca pilosa

As plantas utilizadas na medicina tradicional estão sendo cada vez mais estudadas por serem possíveis fontes de substâncias com atividades antimicrobianas. Dentre elas, destacando-se a Peperomia pellucida (erva-de-jabuti) e a Portulaca pilosa (amor-crescido), utilizadas comumente na Amazônia. A P. pellucida é utilizada, popularmente, em casos de hemorragia, como curativo para feridas, dores abdominais, abscessos, acne, furúnculos, cólicas, problemas renais, hipertensão e colesterol, enquanto a P. pilosa é utilizada como hepato-protetor, antidiarreico, diurético, para queimaduras, erisipelas e ferimentos. Neste trabalho, foram realizadas a abordagem fitoquímica e a atividade antimicrobiana in vitro desses dois materiais vegetais. A prospecção fitoquímica revelou a presença de açúcares redutores, fenóis e taninos, esteroides e triterpenoides, glicosídios cardíacos e carotenoides no extrato etanólico seco (EES) de P. pillosa, e a presença de proteínas e aminoácidos, fenóis e taninos, flavonoides, esteroides e triterpenoides, azulenos, carotenoides, depsídios e depsidonas no EES de P. pellucida. Para avaliação da atividade antimicrobiana dos extratos etanólicos brutos, foi empregado o método de disco difusão em ágar, nas concentrações de 500; 250; 125 e 62,5 µg/mL. Os extratos testados que apresentaram atividade antimicrobiana na avaliação preliminar foram submetidos à determinação da concentração inibitória mínima (CIM) pela técnica de microdiluição em caldo. O extrato de P. pellucida possui atividade antimicrobiana frente a S. aureus e P. aeruginosa, e o de P. pilosa contra Pseudomonas aeruginosa.

Plants used in traditional medicine are under increasing scrutiny as possible sources of substances with antimicrobial activity. In this article we focus on Peperomia pellucida (erva-de-jabuti) and Portulaca pilosa (amor crescido), both commonly used in the Amazon. P. pellucida is popularly used as a wound dressing, to stop bleeding, and in cases of abdominal pain and cramps, abscesses, acne, boils, kidney problems, hypertension and raised cholesterol, and P. pilosa as a hepato-protective, antidiarrheal and diuretic and for burns, erysipelas and injuries. In this study, we investigated the phytochemistry and antimicrobial activity of extracts of these two plant materials. Phytochemical screening revealed the presence of reducing sugars, phenols and tannins, steroids and terpenoids, cardiac glycosides and carotenoids in the dried ethanol extract (DEE) of P. pilosa and of proteins and amino acids, phenols and tannins, flavonoids, steroids and triterpenoids, azulenes, carotenoids, depsides and depsidones in the P. pellucida DEE. The antimicrobial activity of the ethanol extracts was assayed by the agar disc diffusion method, at concentrations of 500, 250, 125 and 62.5µg/mL. The plant extracts that showed antimicrobial activity in the preliminary assessment were subjected to the broth microdilution test to determine the minimum inhibitory concentration (MIC). The P. pellucida extract had antimicrobial activity against S. aureus and P. aeruginosa and that of P. pilosa against P. aeruginosa.

Metabolism of ethionine in ethionine-sensitive and ethionine-resistant cells of the enteric yeast Candida slooffii.

In a defined medium with added ethionine plus low methionine, phenylalanine, tryptophan, tyrosine, adenine, and additional methionine reversed inhibition of the enteric yeast Candida slooffii by ethionine. Isoleucine and 7-methylguanine restored half-maximal growth. Choline but not triethylcholine inhibited C. slooffii. 6-Mercaptopurine reversed ethionine inhibition and also synergistic inhibition by ethionine plus choline. Protection against ethionine by adenine plus aromatics was also evident with log-phase cells in the absence of methionine. Incorporation of ethionine-ethyl-1-(14)C by resting cells was partially inhibited by aromatic amino acids and methionine. Ethionine depressed incorporation of (3)H-phenylalanine but not of (3)H-adenine. Ethionine-resistant mutants were isolated which incorporated ethionine efficiently and degraded it to yet unidentified substances not including 5'-ethylthioadenosine. Ethionine-sensitive cells accumulated more S-adenosylethionine (SAE) than resistant mutants. Adenine was a good precursor of SAE. Radioactivity from ethionine-ethyl-1-(14)C was recovered from cell fractions of ethionine-sensitive cells with the following distribution: cold trichloroacetic acid-soluble > hot trichloroacetic acid-insoluble > lipids > deoxyribonucleic acid > ribonucleic acid. Total radioactivity recovered from ethionine-sensitive cells was twice as much as that from ethionine-resistant mutants.