A laboratory evaluation of cell viability, radiopacity and tooth discoloration induced by regenerative endodontic materials.

AIM: To analyse the cytotoxicity, colour change and radiopacity of MTA Flow (MTA), UltraCal XS (UC) and Bio-C Temp (BT). METHODOLOGY: Human dental pulp cells (hDPCs) stimulated with lipopolysaccharide (LPS) were placed in contact with several dilutions of culture media previously exposed to the experimental materials and tested for cell viability using MTT. Bovine teeth were prepared to simulate an open apex and to mimic extensive crown fracture. The roots were filled with a mixture of agar and blood, and the materials placed over this mixture. The control group consisted of teeth filled only with agar and blood. Colour assessment analyses were performed before and immediately after material insertion and repeated at 30, 45 and 60 days using a spectrophotometer. The total colour change (ΔEab , ΔE00 and whiteness index (WI)) was calculated based on the CIELAB colour space. Digital radiographs were acquired for radiopacity analysis. Cell viability was analysed by one-way anova, whilst differences in colour parameters (ΔEab , ΔE00 and WI) were assessed by two-way repeated measures anova (α = 0.05). Tukey's test was used to compare the experimental groups, and Dunnett's test was used to compare the experimental groups with the control group. RESULTS: MTA, UC and BT had similar cell viability to that of the control group (DMEM) (P > 0.05), except for the BT group at the 1 : 1 and 1 : 2 dilutions, which had significantly lower viability (P < 0.001). All materials were associated with discoloration values greater than what is considered to be the acceptable threshold, and BT resulted in less or similar tooth colour change than MTA and UC, respectively. Decreasing radiopacity over time was observed only in the MTA group (P = 0.007). Lower values of radiopacity were found in the BT group compared with the UC and MTA groups (P < 0.001). CONCLUSIONS: The new bioceramic material (BT) had acceptable cell viability, similar to that of MTA and UC at the highest dilutions, and BT resulted in less tooth colour change than MTA and UC. Despite its lower radiopacity, BT was identified radiographically.

Evaluation of apoptosis/necrosis and cytokine release provoked by three root canal sealers in human polymorphonuclears and monocytes.

AIM: To evaluate the in vitro cytotoxicity and cytokine release of three fresh root canal sealers and to determine the type of cell death they induce. METHODOLOGY: The sealers tested were Sealer 26 (S26), AH Plus (AHP), and Endosequence BC Sealer (END). Fresh sealers were cultivated in contact with monocytes and polymorphonuclears (PMNs) obtained from the peripheral blood of humans. Cell viability, apoptosis and necrosis were analysed at 4 h (PMNs) or 24 h (monocytes) using Annexin-V and propidium iodide in a cytometer. The supernatants were used to quantify Interleukin (IL)-4, IL-6, IL-10, IL-12 and tumour necrosis factor-α (TNF-α) in monocytes and IL-8 in PMNs by ELISA. One-way ANOVA and the Tukey post-test were used to compare data for cytotoxicity, and the multiple T-test was used to determine the differences between sealers in the release of cytokines that were statistically significant. RESULTS: After 4 h of treatment, S26 was associated with greater cell viability than the other sealers (P < 0.05) in the PMN culture and had similar values of necrosis as END (P > 0.05). After 24 h of treatment, AHP and END had greater monocyte cell viability than S26 (P < 0.05), which had more necrosis (P < 0.05). END had the lowest levels of IL-12 compared to the other sealers (P < 0.05) and higher levels of IL-6 compared to S26 (P < 0.05). The tested sealers did not differ in the release of IL-8, IL-10, TNF-α and IL-4 (P > 0.05). CONCLUSIONS: The effect of toxic agents released varied depending on the cell type studied. The composition of the sealers appeared to alter the form of self-regulation in the production of these cytokines by cells.

Effect of different storage media on root dentine composition and viability of fibroblasts evaluated by several assay methods.

AIM: To perform multiparametric analysis of the effects of soya milk (SM), whole milk (WM) and Hank's balanced salt solution (HBSS) on the viability of fibroblasts (HGF). The study also aimed to evaluate the influence of these solutions on bovine root dentine according to OH- and PO43- on the surface. METHODOLOGY: The HGF cytotoxicity was determined according to XTT, NR and SRB assays at 1, 3 and 6 h. Root dentine fragments were assessed by Fourier infrared (FTIR) spectrophotometer before and after immersion in the solutions for the same periods. The positive control group included cells and tooth fragments maintained in Dulbecco's modified Eagle's medium (DMEM), and the negative control included tooth fragments that were kept dry. Data were analysed using anova and Tukey's test. RESULTS: No significant difference was found in cell viability evaluated by XTT (P > 0.05). Using the NR assay, WM and HBSS had significantly lower cell viability compared to the positive control group at 6 h (P < 0.05). SM had similar cell viability to the positive control group at all periods evaluated when assessed using all three tests (P > 0.05). A significant difference was found in values of OH- for the negative control group at 1 h (P = 0.002). CONCLUSIONS: Soya milk promoted better cell viability, whereas on dentine composition, the solutions behaved similarly. The association of different assay methods is promising for improving cell viability analysis. The 1-h time-point is a crucial factor in the prognosis of dental replantation because the teeth remain more hydrated and help maintain cell viability.

An experimental and theoretical study on the electronic and structural properties of CdSe@TiO2 nanotube arrays.

In this work, the effects of the structural (crystallite size, stress) and electronic parameters (band gap, lifetime) on the photoelectrocatalysis and electron transport over CdSe electrodeposited inside TiO2-nanotubes (CdSe@TiO2NT) were investigated. Density functional theory (DFT) calculations of TiO2 were used to elucidate the electronic band structure and to correlate with experimental values. CdSe was grown by pulsed electrodeposition into previous and late thermal-treated TiO2NT (Sample-PTT and Sample-LTT, respectively) without blocking the nanotube's entrance. The Rietveld refinement method was used to obtain information from crystallographic data of each photoelectrode. The lattice strains calculated from the Rietveld analysis for Sample-PTT and Sample-LTT were 0.472 and 0.540, and the average volume of the TiO2-anatase unit cell increased from 133.235(0) Å3 to 136.950(6) Å3, respectively. Sample-PTT exhibited higher experimental electron lifetime, larger than 1.0 order of magnitude compared to Sample-LTT photoanodes. The band structures and DOS obtained by computational modelling showed theoretical band gap values of 2.54 eV and 2.75 eV, which were close to the experimental values. All studies evidenced a strong dependence of the electronic properties of the CdSe@TiO2 samples on their morphology, and, consequently, on their photoelectrochemical activity in water splitting.

Electron scattering by methanol and ethanol: a joint theoretical-experimental investigation.

We present a joint theoretical-experimental study on electron scattering by methanol (CH(3)OH) and ethanol (C(2)H(5)OH) in a wide energy range. Experimental differential, integral and momentum-transfer cross sections for elastic electron scattering by ethanol are reported in the 100-1000 eV energy range. The experimental angular distributions of the energy-selected electrons are measured and converted to absolute cross sections using the relative flow technique. Moreover, elastic, total, and total absorption cross sections for both alcohols are calculated in the 1-500 eV energy range. A complex optical potential is used to represent the dynamics of the electron-alcohol interaction, whereas the scattering equations are solved iteratively using the Padé's approximant technique. Our calculated data agree well with those obtained using the Schwinger multichannel method at energies up to 20 eV. Discrepancies at high energies indicate the importance of absorption effects, included in our calculations. In general, the comparison between our theoretical and experimental results, as well as with other experimental data available in the literature, also show good agreement. Nevertheless, the discrepancy between the theoretical and experimental total cross sections at low incident energies suggests that the experimental cross sections measured using the transmission technique for polar targets should be reviewed.

Peptide mimicking antigenic and immunogenic epitope of neuwiedase from Bothrops neuwiedi snake venom.

Peptides derived from a phage display library may mimic essential features of epitopes (mimotopes), including their immunogenicity. A recombinant peptide library of 12 amino acids displayed on the phage capsid was used to obtain peptides that mimic epitopes of antigens that are reactive to specific polyclonal antibodies anti-neuwiedase (NEU), a toxin from Bothrops neuwiedi snake venom. These polyclonal antibodies are protective against NEU activity and were used as target for the peptide library biopannings, resulting in the selection of 80 peptides. Antibody-binding epitopes were obtained by sequence alignment with the primary and tertiary structures of the NEU protein. Antigenicity and specificity of the mimotopes mixture were confirmed by dot blot, immuno dot blot, plaque reduction and Western blot assays. Their immunogenicity was demonstrated by immunization of BALB/c mice and ELISA tests. The NEU toxin is an important antigen that has many common structural regions to several toxic venom metalloproteinases, in which two epitope regions have been detected. The two mapped epitopes were found in primary sequences of several snake venom toxins, thus demonstrating the potential application of these NEU mimotopes as possible antigen components that are toxicity free.