An In Vitro evaluation of biodegradability of stainless steel crowns at various salivary pH.

AIM: To evaluate the biodegradability of preformed stainless steel crowns at varying salivary pH and the cytotoxic effect of leached out elements on fibroblasts. METHODOLOGY: A total of 243 stainless steel crowns were selected and were divided into 3 groups (I, II, III) based on Ph of immersion media. The pH of samples in group I, II, III were 4.3, 5.5 and 6.3 with 81 crowns in each group. Each group has 9 samples with 8 crowns in each sample. All samples were immersed in polyethylene bottles containing 10ml of artificial saliva and incubated at 37°C for 4 weeks. All the samples were analyzed on 1,7,14 and 21 days by atomic absorption spectrophotometer for the quantitative assement of Ni, Cr and Fe. Fibroblast tissue culture was used to assess the cytotoxicity of the samples. STATISTICAL ANALYSIS: Analysis of variance. RESULTS: Maximum release of Ni, Cr, Fe ions were observed at pH 4.3 followed by pH 5.5 and least release of ions were observed at pH 6.3 from SS crowns. The cytotoxic results showed that the least cell viability of cells was seen at pH 4.3. CONCLUSION: With decrease in pH, there is an increase in ion release from stainless steel crowns and the mean release of nickel, chromium and iron were very much below the average dietary intake. But the allergic manifestations of ions like nickel can't be ruled out.

Effect of Biomineralization Ability on Push-out Strength of Proroot Mineral Trioxide Aggregate, Mineral Trioxide Aggregate Branco, and Calcium Phosphate Cement on Dentin: An In vitro Evaluation.

CONTEXT: Biomineralization is a process which leads to the formation of an interfacial layer with tag-like structures at the cement-dentin interface. It is due to interaction of mineral trioxide aggregate (MTA) and Portland cement with dentin in phosphate-buffered solution (PBS). This study is aimed to evaluate the effect of influence of biomineralization process on push-out bond strength of ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK, USA), MTA Branco (Angelus Soluc¸o˜es Odontolo´gicas, Londrina, PR, Brazil) and calcium phosphate cement (BioGraft CPC). AIM: The aim of this study was to evaluate the effect of biomineralization process on the push-out strength of ProRoot MTA, MTA Branco, and CPC after mixing with 0.2% chlorhexidine gluconate solution (0.2% CHX) and 2% lidocaine solution (2% LA) on the bond strength of MTA-dentin. MATERIALS AND METHODS: Dentin discs with uniform cavities were restored with ProRoot MTA, MTA Branco, and calcium phosphate cement after mixing with 0.2% CHX solution and 2% lidocaine solution. The samples were uniformly distributed into two groups. Experimental group being immersed in PBS solution and control group being immersed in saline for 2 months. Instron testing machine (Model 4444; Instron Corp., Canton, MA, USA) was used to determine the bond strength. STATISTICAL ANALYSIS USED: A two-way analysis of variance and post hoc analysis by Bonferroni test. RESULTS: All samples immersed in experimental group displayed a significantly greater resistance to displacement than that observed for the samples in control group (P < 0.05). MTAs displayed a significantly greater resistance to displacement than calcium phosphate cements. CONCLUSION: The main conclusion of this study was that the push-out bond strength of the cements, mainly the MTA groups, was positively influenced by the biomineralization process.

Effect of recasting on element release from base metal dental casting alloys in artificial saliva and saline solution.

AIM: The aim of this study was to quantitatively estimate the concentration of ion release from recasted base metal alloys in various pH conditions using atomic absorption spectroscopy (AAS). MATERIALS AND METHODS: Specimens of commercially available dental casting alloys (cobalt [Co]-chromium [Cr] and nickel [Ni]- chromium [Cr]) were prepared using lost-wax casting techniques and were stored in the test solution for 1 week and 4 weeks, and ions released during chemical corrosion were detected using AAS. RESULTS: An increase in the quantity of ion release was observed with recasting. These changes were higher after twice recasting in Ni-Cr alloy.

Copper-Catalyzed Tandem O-Arylation-Oxidative Cross Coupling: Synthesis of Chromone Fused Pyrazoles.

Intermolecular tandem copper-catalyzed O-arylation-oxidative acylation (cross dehydrogenative coupling-CDC) has been developed under air as an oxidant. The reaction between 2,4-dihydro-3H-pyrazol-3-ones and ortho-halo aryl carboxaldehydes furnished the corresponding chromone fused pyrazoles, in a straightforward manner. The synthetic utility of the presented tandem catalysis has been demonstrated with the synthesis of an A2-subtype selective adenosine receptor antagonist in only two steps.

Prediction of peptidoglycan hydrolases- a new class of antibacterial proteins.

BACKGROUND: The efficacy of antibiotics against bacterial infections is decreasing due to the development of resistance in bacteria, and thus, there is a need to search for potential alternatives to antibiotics. In this scenario, peptidoglycan hydrolases can be used as alternate antibacterial agents due to their unique property of cleaving peptidoglycan cell wall present in both gram-positive and gram-negative bacteria. Along with a role in maintaining overall peptidoglycan turnover in a cell and in daughter cell separation, peptidoglycan hydrolases also play crucial role in bacterial pathophysiology requiring development of a computational tool for the identification and classification of novel peptidoglycan hydrolases from genomic and metagenomic data. RESULTS: In this study, the known peptidoglycan hydrolases were divided into multiple classes based on their site of action and were used for the development of a computational tool 'HyPe' for identification and classification of novel peptidoglycan hydrolases from genomic and metagenomic data. Various classification models were developed using amino acid and dipeptide composition features by training and optimization of Random Forest and Support Vector Machines. Random Forest multiclass model was selected for the development of HyPe tool as it showed up to 71.12 % sensitivity, 99.98 % specificity, 99.55 % accuracy and 0.80 MCC in four different classes of peptidoglycan hydrolases. The tool was validated on 24 independent genomic datasets and showed up to 100 % sensitivity and 0.94 MCC. The ability of HyPe to identify novel peptidoglycan hydrolases was also demonstrated on 24 metagenomic datasets. CONCLUSIONS: The present tool helps in the identification and classification of novel peptidoglycan hydrolases from complete genomic or metagenomic ORFs. To our knowledge, this is the only tool available for the prediction of peptidoglycan hydrolases from genomic and metagenomic data. AVAILABILITY: http://metagenomics.iiserb.ac.in/hype/ and http://metabiosys.iiserb.ac.in/hype/ .

The efficiency of 2.5% sodium hypochlorite in preventing inoculation of periapical tissues with contaminated patency files: An ex vivo evaluation.

The purpose of this in vitro study was to analyze the effectiveness of 2.5% sodium hypochlorite (NaOCl) in preventing inoculation of periapical tissue with contaminated patency files. Fifty single-rooted teeth with single canals were used in the study. They were randomly divided into five groups of which two were experimental groups, two positive controls, and one negative control group. After root canal preparation, teeth in Group I (experimental) were filled with 2.5 NaOCl and #15 stainless steel K-files contaminated with Streptococcus sanguis (ATCC# 10556) were allowed to pass through the root canal into the culture medium and cultured. Teeth in Group II (experimental) were also filled with NaOCl, but contaminated files used in this group were immersed in 2.5% NaOCl for 10 s prior to being placed in the canal. The negative control used sterile files pass through 2.5% NaOCl into the culture medium. The first positive control used contaminated patency files in teeth with saline. The second positive control group placed contaminated files into broth next to teeth filled with NaOCl (to evaluate potential chlorine leakage). The results were as follows. Both the experimental groups and the negative control group showed no growth. Both the positive control groups 100% growth for S. sanguis. This indicates that the NaOCl present in the canal after irrigation was sufficient to kill the test organism.

Sealing ability of white and gray mineral trioxide aggregate mixed with distilled water and 0.12% chlorhexidine gluconate as a root end filling material: an ex vivo evaluation.

AIM: The aim of this study was to evaluate the sealing ability of white and gray mineral trioxide aggregate (MTA) mixed with distilled water and 0.12% chlorhexidine (CHX) gluconate when used as a root-end filling material using the dye-penetration technique. MATERIALS AND METHODS: A total of 48 single-rooted human teeth were cleaned, shaped, and obturated with gutta-percha and AH Plus sealer. The apical 3 mm of each root was resected, and 3-mm deep root-end cavity preparations were made. The teeth were randomly divided into 4 experimental groups, each containing 8 teeth, and 2 negative and positive control groups, each containing 8 teeth. Root-end cavities in the experimental groups were filled with the experimental materials. After application of nail polish, the teeth were exposed to India ink for 72 h and longitudinally sectioned, and the extent of dye penetration was measured with a stereomicroscope. RESULTS: No statistically significant differences were observed in the sealing ability of gray and white MTA mixed with distilled water and 0.12% CHX. CONCLUSION: CHX appears to be a good alternative to replace distilled water, as a solution to be mixed with MTA.

Gold nanoparticles from pro and eukaryotic photosynthetic microorganisms--comparative studies on synthesis and its application on biolabelling.

Today, a material science focuses on the nanoparticles synthesis in general and synthesizing them by biological entity in particular for their marvel production and its remarkable property. In this present study, synthesis of gold nanoparticles using photosynthetic microorganisms such as Coelastrella sp. (eukaryotes) and Phormidium sp. (prokaryotes) were reacted with Chloroauric acid (HAuCl(4)) and bioaccumulation was assessed. Various techniques were adopted for characterization of nanoparticles and compared. It was found to be 25 nm sized nanotriangles and 30 nm sized spherical shaped nanoparticles were synthesized by prokaryotic and eukaryotic microorganisms respectively by TEM analysis. Biogenic gold nanoparticles have potent antioxidant property and the interaction of gold nanoparticles with DNA was evaluated that biogenic nanoparticles were actively bound to DNA in increased concentration. It was revealed that biogenic nanoparticles have wide range of applications depends on the biological entity used. Selection of suitable biological entity is very much important for the production of nanoparticles with desirable shapes and size for the biomedical applications.

Coronal microleakage with five different temporary restorative materials following walking bleach technique: An ex-vivo study.

CONTEXT: Walking bleach technique uses 30% hydrogen peroxide and sodium perborate, and this paste mixture causes loosening of the coronal temporary restorative materials and thus decreasing its clinical effectiveness and causing irritation to the patients oral tissues. In the present study, sealing ability of hygroscopic coronal temporary restorative materials were compared with the other commonly used temporary restorative materials. AIM: To evaluate the effects of walking bleach material on the marginal sealing ability and coronal microleakage of the hydrophilic temporary restorative materials with that of the other commonly used temporary restorative materials in endodontic practice. MATERIALS AND METHODS: Seventy-five extracted human maxillary central incisor teeth were prepared chemo-mechanically and obturated with gutta-percha in lateral condensation technique. Surface of each tooth was double coated with cyanoacrylate glue. All the teeth were randomly divided in to five groups. Out of 15 teeth in each group, 10 teeth served as experimental specimens, in which bleaching agent was placed in the pulp chamber and 5 teeth served as control, in which no bleaching agent was placed. The access cavities were restored with temporary restorative materials being tested per each group respectively. The specimens were then immersed in 1% India ink dye and subjected to thermo cycling for 7 days. All the teeth were longitudinally sectioned and observed with stereomicroscope and were graded according to the depth of linear dye penetration. STATISTICAL ANALYSIS USED: Mann-Whitney U test and Kruskal-Wallis test. RESULTS: Hydrophilic temporary restorative materials Cavit G and Coltosol F have shown minimal coronal dye leakage with better sealing ability when exposed to walking bleach paste mixture in the dye penetration tests compared to other commonly used temporary restorative materials. CONCLUSION: Marginal sealing ability of Cavit G and Coltosol F were not influenced by the effects of bleaching agent compared to other temporary restorative materials used in the study.

Synthetic and antibacterial studies on some new furanopeptides.

A series of new furanopeptides (3) are prepared by the coupling of arylsubstituted furoic acids (1) with amino acid methyl esters, di and tetra-peptide methyl esters using dicyclohexyl carbodiimide (DCC) as coupling agent. Some of the newly synthesized compounds are characterized on the basis of IR, 1H NMR, mass spectral data and elemental analysis. Some of the selected compounds are also tested for their antibacterial properties.