Efficacy of EDTA-T gel for smear layer removal at root surfaces

Objective: The purpose of this in vitro study was to investigate the efficacy of EDTA gel preparation, associated with texapon detergent (EDTA-T), for removing the smear layer at human root surfaces. Method and materials: An experimental smear layer was produced by scaling using periodontal curettes, and the root surfaces were etched with the following concentrations of EDTA-T: 5%, 10%, 15%, 20%, 24%, and negative control (saline solution) for 1, 2, or 3 minutes using both passive and active methods. The surfaces were evaluated by scanning electron microscopy, and photomicrographs were evaluated in relation to smear removal. Results: All EDTA-T groups were more effective than the control group (P < .0001). EDTA-T at 15% was more effective when applied by the passive method, although this difference was not observed for the active method. The active method was statistically better than the passive method (P < .0001). Conclusion: The etching of the root surface with EDTA-T gel by active application, independently of the other factors evaluated, was effective for smear layer removal.

Effects of basic fibroblast growth factor on density and morphology of fibroblasts grown on root surfaces with or without conditioning with tetracycline or EDTA.

A study was conducted to evaluate in vitro the effect of root surface conditioning with basic fibroblast growth factor (b-FGF) on morphology and proliferation of fibroblasts. Three experimental groups were used: non-treated, and treated with 50 microg or 125 microg b-FGF/ml. The dentin samples in each group were divided into subgroups according to the chemical treatment received before application of b-FGF: none, or conditioned with tetracycline-HCl or EDTA. After contact with b-FGF for 5 min, the samples were incubated for 24 h with 1 ml of culture medium containing 1 x 10(5) cells/ml plus 1 ml of culture medium alone. The samples were then subjected to routine preparation for SEM, and random fields were photographed. Three calibrated and blind examiners performed the assessment of morphology and density according to two index systems. Classification and regression trees indicated that the root surfaces treated with 125 microg b-FGF and previously conditioned with tetracycline-HCl or EDTA presented a morphology more suggestive of cellular adhesion and viability (P = 0.004). The density of fibroblasts on samples previously conditioned with EDTA, regardless of treatment with b-FGF, was significantly higher than in the other groups (P < 0.001). The present findings suggest that topical application of b-FGF has a positive influence on both the density and morphology of fibroblasts.

Crescimento de Mentha piperita L, cultivada em solução nutritiva com diferentes doses de potássio

The research aimed at the evaluation of the influence of different potassium doses on the growth and development of Mentha piperita L. The experiment was conducted with stalks rooted in a commercial substrate and transplanted to a complete nutritive solution varying the treatments as following: (a) 234 mg L-1 of K; (b) 117 mg L-1 of K; and (c) 58.5 mg L-1 of K. Plants were evaluated at 21, 42, 63, 84 and 105 days after transplanting (DAT). In this study there were determined the physiological indexes leaf area ratio (LAR), specific leaf area (SLA), net assimilatory rate (NAR) and relative growth rate (RGR) were determined. The results indicated that the decreasing of K concentration to 25% did not affect the LAR, SLA, NAR and RGR physiological indexes.

Microwave-induced fast decalcification of rat bone for electron microscopic analysis: An ultrastructural and cytochemical study

Bone decalcification is a time-consuming process. It takes weeks and preservation of the tissue structure depends on the quality and velocity of the demineralization process. In the present study, a decalcification methodology was adapted using microwaving to accelerate the decalcification of rat bone for electron microscopic analysis. The ultrastructure of the bone decalcified by microwave energy was observed. Wistar rats were perfused with paraformaldehyde and maxillary segments were removed and fixed in glutaraldehyde. Half of specimens were decalcified by conventional treatment with immersion in Warshawsky solution at 4oC during 45 days, and the other half of specimens were placed into the beaker with 20 mL of the Warshawsky solution in ice bath and thereafter submitted to irradiation in a domestic microwave oven (700 maximum power) during 20 s/350 W/±37°C. In the first day, the specimens were irradiated 9 times and stored at 40°C overnight. In the second day, the specimens were irradiated 20 times changing the solution and the ice after each bath. After decalcification, some specimens were postfixed in osmium tetroxide and others in osmium tetroxide and potassium pyroantimonate. The specimens were observed under transmission electron microscopy. The results showed an increase in the decalcification rate in the specimens activated by microwaving and a reduction of total experiment time from 45 days in the conventional method to 48 hours in the microwave-aided method.

Production and partial characterization of keratinase produced by a microorganism isolated from poultry processing plant wastewater

A Streptomyces was isolated from poultry plant wastewater, showed high keratinolytic activity when cultured on feather meal medium. Optimum keratinolytic activity was observed at 40°C and pH 8.0. The enzyme also showed to be stable between 40 and 60°C. The keratinolytic activity was not inhibited by EDTA, DMSO and Tween 80. On the other hand, CaCl2, ZnCl2, and BaCl2 slightly inhibited the keratinolytic activity. The Streptomyces isolated might be useful in leather, keratin waste treatment, animal feeding industry, and also cosmetic industry. © 2008 Academic Journals.

Myotoxic phospholipases A2 isolated from Bothrops brazili snake venom and synthetic peptides derived from their C-terminal region: Cytotoxic effect on microorganism and tumor cells

This paper reports the purification and biochemical/pharmacological characterization of two myotoxic phospholipases A2 (PLA2s) from Bothrops brazili venom, a native snake from Brazil. Both myotoxins (MTX-I and II) were purified by a single chromatographic step on a CM-Sepharose ion-exchange column up to a high purity level, showing Mr ∼ 14,000 for the monomer and 28,000 Da for the dimer. The N-terminal and internal peptide amino acid sequences showed similarity with other myotoxic PLA2s from snake venoms, MTX-I belonging to Asp49 PLA2 class, enzymatically active, and MTX-II to Lys49 PLA2s, catalytically inactive. Treatment of MTX-I with BPB and EDTA reduced drastically its PLA2 and anticoagulant activities, corroborating the importance of residue His48 and Ca2+ ions for the enzymatic catalysis. Both PLA2s induced myotoxic activity and dose-time dependent edema similar to other isolated snake venom toxins from Bothrops and Crotalus genus. The results also demonstrated that MTXs and cationic synthetic peptides derived from their 115-129 C-terminal region displayed cytotoxic activity on human T-cell leukemia (JURKAT) lines and microbicidal effects against Escherichia coli, Candida albicans and Leishmania sp. Thus, these PLA2 proteins and C-terminal synthetic peptides present multifunctional properties that might be of interest in the development of therapeutic strategies against parasites, bacteria and cancer. © 2008 Elsevier Inc. All rights reserved.

Calcium hydroxide intracanal dressing removal with different rotary instruments and irrigating solutions: A scanning electron microscopy study

This study evaluated the efficacy of 2 types of rotary instruments employed in association with sodium hypochlorite (NaOCl) or EDTA in removing calcium hydroxide (CH) residues from root canals dentin walls. Forty-two mandibular human incisors were instrumented with the ProTaper System up to F2 instrument, irrigated with 2.5% NaOCl followed by 17% EDTA and filled with a CH intracanal dressing. After 7 days, the CH dressing was removed using 4 techniques: NiTi rotary instrument size 25, 0.06 taper (K3 Endo) and irrigation with 17% EDTA (Group 1), NiTi rotary F1 instrument (ProTaper) and irrigation with 17% EDTA (Group 2), NiTi rotary instrument size 25, 0.06 taper and irrigation with 2.5% NaOCl (Group 3) and NiTi rotary F1 instrument and irrigation with 2.5% NaOCl (Group 4). Two roots without intracanal dressing were used as negative controls. Teeth were evaluated by scanning electron microscopy, in the cervical and apical canal thirds. None of the techniques removed the CH dressing completely. In the apical and cervical thirds, F1 instrument was better than instrument size 25, 0.06 taper in removing CH residues (p<0.05), regardless of the final irrigating solution. No difference was found between the irrigating solutions in the groups of F1 instrument and of instrument size 25, 0.06 taper (p>0.05). The negative controls had no CH residues on the dentin walls. In conclusion, the ProTaper F1 instrument was better than K3 Endo instrument size 25, 0.06 taper in the removal of CH intracanal medication, regardless of irrigating solution used.

Influence of dental exposure to oral environment on smear layer removal and collagen exhibition after using different conditioning agents

Although in vitro studies have shown encouraging results for root surface conditioning with demineralizing agents, in vivo studies have failed to show its benefits in periodontal healing. This can be attributed to several factors, among which, the hypermineralization of dental surface. Therefore, this in vitro study compared, using scanning electron microscopy (SEM), the effect of root surface conditioning with different conditioners (1% and 25% citric acid, 24% EDTA and 50 mg/mL tetracycline hydrochloride) in impacted teeth and in teeth that had their roots exposed to the oral environment. One trained examiner assessed the SEM micrographs using a root surface modification index. There was a tendency of more root surface modification in the group of impacted teeth, suggesting that the degree of root mineralization influences its chemical demineralization.

Pharmacokinetics of dexmedetomidine administered intravenously in isofluraneanesthetized cats

Objective-To determine the pharmacokinetics of dexmedetomidine administered as a short-duration IV infusion in isoflurane-anesthetized cats. Animals-6 healthy adult domestic female cats. Procedures-Dexmedetomidine hydrochloride was injected IV (10 μg/kg over 5 minutes [rate, 2 μg/kg/min]) in isoflurane-anesthetized cats. Blood samples were obtained immediately prior to and at 1, 2, 5, 6, 7, 10, 15, 30, 60, 90, 120, 240, and 480 minutes following the start of the IV infusion. Collected blood samples were transferred to tubes containing EDTA, immediately placed on ice, and then centrifuged at 3,901 X g for 10 minutes at 4°C. The plasma was harvested and stored at -20°C until analyzed. Plasma dexmedetomidine concentrations were determined by means of liquid chromatography-mass spectrometry. Dexmedetomidine plasma concentration-time data were fitted to compartmental models. Results-A 2-compartment model with input in and elimination from the central compartment best described the disposition of dexmedetomidine administered via short-duration IV infusion in isoflurane-anesthetized cats. Weighted mean ± SEM apparent volume of distribution of the central compartment and apparent volume of distribution at steady-state were 402 ± 47 mL/kg and 1,701 ± 200 mL/kg, respectively; clearance and terminal half-life (harmonic mean ± jackknife pseudo-SD) were 6.3 ± 2.8 mL/min/kg and 198 ± 75 minutes, respectively. The area under the plasma concentration curve and maximal plasma concentration were 1,061 ± 292 min·ng/mL and 17.6 ± 1.8 ng/mL, respectively. Conclusions and Clinical Relevance-Disposition of dexmedetomidine administered via short-duration IV infusion in isoflurane-anesthetized cats was characterized by a moderate clearance and a long terminal half-life.

Blood cells attachment after root conditioning and PRP application: An in vitro study

Aim: Root conditioning is aimed at smear layer removal and at dental matrix collagen exposure, which may promote periodontal regeneration. This in vitro study assessed smear layer removal, collagen fiber exposure and the influence of PRP (platelet-rich plasma) application on adhesion of blood cells to the root surface using scanning electron microscopy (SEM). Materials and methods: Scaled root samples (n = 160) were set in five groups and conditioned with: group I - control group (saline solution); group II (EDTA 24%); group III (citric acid 25%); group IV (tetracycline hydrochloride 50 mg/ml); group V (sodium citrate 30%). Eighty samples were assessed using the root surface modification index (RSMI). The other eighty samples were set in two groups. The first group (n = 40) received PRP gel application with a soft brush and the second group (n = 40) received PRP application and then a blood drop. The fibrin clot formation was assessed in the first group and the blood cells adhesion was assessed in the second group using the BEAI (blood elements adhesion index). A previously trained, calibrated, and blind examiner evaluated photomicrographs. Statistical analysis was performed using the Kruskal-Wallis's and Dunn's tests. Results: Group III attained the best results for RSMI and BEAI. Moreover, it was the only group showing fibrin clot formation. Conclusion: Citric acid was the most efficient conditioner for smear layer removal, collagen fiber exposure and blood cell adhesion. Moreover, it was the only group showing fibrin clot formation after PRP application. Clinical significance: This study demonstrated that root conditioning followed by PRP application may favor blood cell adhesion on root surface which may optimize periodontal healing.

Efeitos do condicionamento radicular com diferentes agentes para a adesão de plasma rico em plaquetas e de células sanguíneas: estudo in vitro

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeito do condicionamento radicular na reparação periodontal de defeitos tipo deiscência: Estudo experimental em cães

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência de diferentes tratamentos físico-químicos na adesão e viabilidade de fibroblastos de ligamento periodontal à superfície radicular simulando dentes avulsionados

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

No evidence for association of ataxia-telangiectasia mutated gene T2119C and C3161G amino acid substitution variants with risk of breast cancer

Background There is evidence that certain mutations in the double-strand break repair pathway ataxia-telangiectasia mutated gene act in a dominant-negative manner to increase the risk of breast cancer. There are also some reports to suggest that the amino acid substitution variants T2119C Ser707Pro and C3161G Pro1054Arg may be associated with breast cancer risk. We investigate the breast cancer risk associated with these two nonconservative amino acid substitution variants using a large Australian population-based case–control study. Methods The polymorphisms were genotyped in more than 1300 cases and 600 controls using 5' exonuclease assays. Case–control analyses and genotype distributions were compared by logistic regression. Results The 2119C variant was rare, occurring at frequencies of 1.4 and 1.3% in cases and controls, respectively (P = 0.8). There was no difference in genotype distribution between cases and controls (P = 0.8), and the TC genotype was not associated with increased risk of breast cancer (adjusted odds ratio = 1.08, 95% confidence interval = 0.59–1.97, P = 0.8). Similarly, the 3161G variant was no more common in cases than in controls (2.9% versus 2.2%, P = 0.2), there was no difference in genotype distribution between cases and controls (P = 0.1), and the CG genotype was not associated with an increased risk of breast cancer (adjusted odds ratio = 1.30, 95% confidence interval = 0.85–1.98, P = 0.2). This lack of evidence for an association persisted within groups defined by the family history of breast cancer or by age. Conclusion The 2119C and 3161G amino acid substitution variants are not associated with moderate or high risks of breast cancer in Australian women.