Effect Of Dental Bleaching After Bracket Bonding And Debonding Using Three Different Adhesive Systems

To evaluate the influence of bonding and debonding of orthodontic brackets on dental in-home bleaching, taking into account three different adhesive systems. Methods: Forty-four bovine incisors were divided into four groups according to the primer system used for orthodontic bracket bonding. Following the debonding of orthodontic brackets, the teeth were stored in staining solution for 96 hours. Then, teeth were whitened using 10% carbamide peroxide for two weeks at a 6-hour-a-day regime. Standardized digital photographs were taken at the following intervals: T0 (initial); T1 (after debonding); T2 (after pigmentation); T3, T4 and T5 representing 1, 7, and 14 days of bleaching. Repeatability and stability tests were carried out to check the method accuracy. Images were analyzed using Adobe Photoshop 7.0 software considering (L*a*b*)color coordinate values and a modified color difference total (ΔE'). Results: The results of this study (ANOVA and Tukey; p < 0.01) demonstrated that after 7 days of bleaching, experimental groups showed significantly less teeth whitening compared to the control group. However, there were no significant color differences between the groups after 14 days, according to values of lightness (L*). Conclusions: Regardless of the adhesive primer system applied, bonding and debonding of orthodontic brackets alters the outcome of tooth whitening in the first 7 days of bleaching, however it has no influence on the whitening of the dental structure after 14 days of in-home dental bleaching with 10% carbamide peroxide. © 2013 Dental Press Journal of Orthodontics.1826168Feinman, R.A.B., Madray, G., Yarborough, D., Chemical, optical and physiologic mechanisms of bleaching products: A review (1991) Pract Periodontics Aesthet Dent., 3 (2), pp. 32-36Diedrich, P., Enamel alterations from bracket bonding and debonding: A study with the scanning electron microscope (1981) Am J Orthod., 79 (5), pp. 500-522Menezes, L.F.S., Chevitarese, O., Sealant and resin viscosity and their influence on formation of resin tags (1995) Angle Orthod., 64 (5), pp. 383-388Zachrisson, B.U., Artun, J., Enamel surface appearance after various debonding techniques (1979) Am J Orthod., 75, pp. 121-137Hintz, J.K., Bradley, T.G., Eliades, T., Enamel colour changes following whitening with 10 per cent carbamide peroxide: A comparison of orthodontically-bonded/ debonded and untreated teeth (2001) Eur J Orthod., 23 (4), pp. 411-415Villalta, P., Lu, H., Okte, Z., Garcia-Godoy, F., Powers, J.M., Effects of staining and bleaching on color change of dental composite resin (2006) J Prosthet Dent., 95 (2), pp. 137-142Eliades, G.C., Vougiouklakis, G.J., Caputo, A.A., Degree of double bond conversion in light-cured composites (1987) Dent Mater., 3 (1), pp. 19-25Chamda, R.A., Stein, E., Time-related bond strengths of light-cured and chemically cured bonding systems: An in vitro study (1996) Am J Orthod Dentofacial Orthop., 110 (4), pp. 378-382Zachrisson, B.U., Bonding in orthodontics (2000) Orthodontics: Current principles and techniques, p. 1040. , In: Graber TM, Vanarsdall RL. 3rd ed. St. Louis: MosbyAlves, E.A., Alves, F.K.A., Campos, E.J., Mathias, P., Susceptibility to caries-like lesions after dental bleaching with different techniques (2007) Quintessence Int., 38 (7), pp. e404-e409Bentley, C., Leonard, R.H., Nelson, C.F., Bentley, S.A., Quantitation of vital bleaching by computer analysis of photographic images (1999) J Am Dental Assoc., 130 (6), pp. 809-816Seghi, R.R., Johnston, W.M., O'Brien, W.J., Performance assessment of colorimetric devices on dental porcelains (1989) J Dent Res., 68 (12), pp. 1755-1759Gerlach, R.W., Barker, M.L., Sagel, P.A., Objective and subjective whitening response of two self-directed bleaching systems (2000) Am J Dent., 21, pp. 22-28Gerlach, R.W., Gibb, R.D., Sagel, P.A., A randomized clinical trial comparing a novel 5.3% hydrogen peroxide bleaching strip to 10%, 15% and 20% carbamide peroxide tray-based bleaching systems (2002) Compend Contin Educ Dent., 15, pp. 7-12Scotti, R., Mascellani, S.C., Fornit, F., The in vitro color stability of acrylic resins for provisional restorations (1997) Int J Prosthodont., 10 (2), pp. 164-168Dietschi, D., Campanile, G., Holz, J., Meyer, J.M., Comparison of the color stability of ten new generation composites: An in vitro study (1994) Dent Mater., 10 (6), pp. 353-362Dozic, A., Kleverlaan, C.J., Aartman, I.H.A., Feilzer, A.J., Relation in color of three regions of vital human incisors (2004) Dent Mater., 20 (9), pp. 832-838Eliades, T., Kakaboura, A., Eliades, G., Bradley, T.G., Comparison of enamel colour changes associated with orthodontic bonding using two different adhesives (2001) Eur J Orthod., 23 (1), pp. 85-90O'Brien, W.J., Hemmendinger, H., Boenke, K.M., Linger, J.B., Groh, C.L., Color distribution of three regions of extracted human teeth (1997) Dent Mater., 13 (3), pp. 179-185Dozic, A., Kleverlaan, C.J., Aartman, I.H.A., Feilzer, A.J., Relation in color among maxillary incisors and canines (2005) Dent Mater., 21 (3), pp. 187-191Ruyter, I.E., Nilner, K., Moller, B., Color stability of dental composite resin materials for crown and bridge veneers (1987) Dent Mater., 3 (5), pp. 246-251Johnston, W.N., Kao, E.C., Assessment of appearance match by visual observation and clinical colorimetry (1998) J Dent Res., 68 (5), pp. 819-822Osório, L.B., (2000) Alterações cromáticas e micromorfológicas do esmalte submetido ao procedimento de clareamento pós-descolagem, , [thesis]. 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Light-Front Approach for Pentaquark Strong Decays

Assuming the two diquark structure for the pentaquark state as advocated in the Jaffe-Wilczek model, we study the strong decays of light and heavy parity-even pentaquark states using the light-front quark model in conjunction with the spectator approximation. The narrowness of the Theta width is ascribed to the p-wave configuration of the diquark pair. Taking the Theta width as a benchmark, we estimate the rates of the strong decays Xi_{3/2}-- to Xi- pi-, Sigma- K-, Sigma_{5c}0 to D_s- p, D_{s0}*- p and Xi_{5c}0 to D_s- Sigma+, D_{s0}^{*-} Sigma+ with Sigma_{5c} Xi_{5c} being antisextet charmed pentaquarks and D_{s0}* a scalar strange charmed meson. The ratio of Gamma(P_c to Baryon D_{s0}*)/Gamma(P_c to Baryon D_s) is very useful for verifying the parity of the antisextet charmed pentaquark P_c. It is expected to be of order unity for an even parity P_c and much less than one for an odd parity pentaquark.Comment: 24 pages, 2 figure

Light-Front Approach for Heavy Pentaquark Transitions

Assuming the two diquark structure for the pentaquark state as advocated in the Jaffe-Wilczek model, there exist exotic parity-even anti-sextet and parity-odd triplet heavy pentaquark baryons. The theoretical estimate of charmed and bottom pentaquark masses is quite controversial and it is not clear whether the ground-state heavy pentaquark lies above or below the strong-decay threshold. We study the weak transitions of heavy pentaquark states using the light-front quark model. In the heavy quark limit, heavy-to-heavy pentaquark transition form factors can be expressed in terms of three Isgur-Wise functions: two of them are found to be normalized to unity at zero recoil, while the third one is equal to 1/2 at the maximum momentum transfer, in accordance with the prediction of the large-Nc approach or the quark model. Therefore, the light-front model calculations are consistent with the requirement of heavy quark symmetry. Numerical results for form factors and Isgur-Wise functions are presented. Decay rates of the weak decays Theta_b+ to Theta_c0 pi+ (rho+), Theta_c0 to Theta+ pi- (rho-), Sigma'_{5b}+ to Sigma'_{5c}0 pi+ (rho+) and Sigma'_{5c}0 to N_8+ pi- (rho-) with Theta_Q, Sigma'_{5Q} and N_8 being the heavy anti-sextet, heavy triplet and light octet pentaquarks, respectively, are obtained. For weakly decaying Theta_b+ and Theta_c0, the branching ratios of Theta_b+ to Theta_c0 pi+, Theta_c0 to Theta+ pi- are estimated to be at the level of 10^{-3} and a few percents, respectively.Comment: 33 pages, 3 figures, version to be published in Phys. Rev.

Reduced SLIT2 is associated with increased cell proliferation and arsenic trioxide resistance in acute promyelocytic Leukemia

The SLIT-ROBO axis plays an important role in normal stem-cell biology, with possible repercussions on cancer stem cell emergence. Although the Promyelocytic Leukemia (PML) protein can regulate SLIT2 expression in the central nervous system, little is known about SLIT2 in acute promyelocytic leukemia. Hence, we aimed to investigate the levels of SLIT2 in acute promyelocytic leukemia (APL) and assess its biological activity in vitro and in vivo. Our analysis indicated that blasts with SLIT2high transcript levels were associated with cell cycle arrest, while SLIT2low APL blasts displayed a more stem-cell like phenotype. In a retrospective analysis using a cohort of patients treated with all-trans retinoic acid (ATRA) and anthracyclines, high SLIT2 expression was correlated with reduced leukocyte count (p = 0.024), and independently associated with improved overall survival (hazard ratio: 0.94; 95% confidence interval: 0.92–0.97; p < 0.001). Functionally, SLIT2-knockdown in primary APL blasts and cell lines led to increased cell proliferation and resistance to arsenic trioxide induced apoptosis. Finally, in vivo transplant of Slit2-silenced primary APL blasts promoted increased leukocyte count (p = 0.001) and decreased overall survival (p = 0.002) compared with the control. In summary, our data highlight the tumor suppressive function of SLIT2 in APL and its deteriorating effects on disease progression when downregulated

The genetic architecture of the human cerebral cortex

INTRODUCTION The cerebral cortex underlies our complex cognitive capabilities. Variations in human cortical surface area and thickness are associated with neurological, psychological, and behavioral traits and can be measured in vivo by magnetic resonance imaging (MRI). Studies in model organisms have identified genes that influence cortical structure, but little is known about common genetic variants that affect human cortical structure. RATIONALE To identify genetic variants associated with human cortical structure at both global and regional levels, we conducted a genome-wide association meta-analysis of brain MRI data from 51,665 individuals across 60 cohorts. We analyzed the surface area and average thickness of the whole cortex and 34 cortical regions with known functional specializations. RESULTS We identified 306 nominally genome-wide significant loci (P < 5 × 10−8) associated with cortical structure in a discovery sample of 33,992 participants of European ancestry. Of the 299 loci for which replication data were available, 241 loci influencing surface area and 14 influencing thickness remained significant after replication, with 199 loci passing multiple testing correction (P < 8.3 × 10−10; 187 influencing surface area and 12 influencing thickness). Common genetic variants explained 34% (SE = 3%) of the variation in total surface area and 26% (SE = 2%) in average thickness; surface area and thickness showed a negative genetic correlation (rG = −0.32, SE = 0.05, P = 6.5 × 10−12), which suggests that genetic influences have opposing effects on surface area and thickness. Bioinformatic analyses showed that total surface area is influenced by genetic variants that alter gene regulatory activity in neural progenitor cells during fetal development. By contrast, average thickness is influenced by active regulatory elements in adult brain samples, which may reflect processes that occur after mid-fetal development, such as myelination, branching, or pruning. When considered together, these results support the radial unit hypothesis that different developmental mechanisms promote surface area expansion and increases in thickness. To identify specific genetic influences on individual cortical regions, we controlled for global measures (total surface area or average thickness) in the regional analyses. After multiple testing correction, we identified 175 loci that influence regional surface area and 10 that influence regional thickness. Loci that affect regional surface area cluster near genes involved in the Wnt signaling pathway, which is known to influence areal identity. We observed significant positive genetic correlations and evidence of bidirectional causation of total surface area with both general cognitive functioning and educational attainment. We found additional positive genetic correlations between total surface area and Parkinson’s disease but did not find evidence of causation. Negative genetic correlations were evident between total surface area and insomnia, attention deficit hyperactivity disorder, depressive symptoms, major depressive disorder, and neuroticism. CONCLUSION This large-scale collaborative work enhances our understanding of the genetic architecture of the human cerebral cortex and its regional patterning. The highly polygenic architecture of the cortex suggests that distinct genes are involved in the development of specific cortical areas. Moreover, we find evidence that brain structure is a key phenotype along the causal pathway that leads from genetic variation to differences in general cognitive function

Measurement of the cross section for isolated-photon plus jet production in pp collisions at √s=13 TeV using the ATLAS detector

The dynamics of isolated-photon production in association with a jet in proton–proton collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset with an integrated luminosity of 3.2 fb−1. Photons are required to have transverse energies above 125 GeV. Jets are identified using the anti- algorithm with radius parameter and required to have transverse momenta above 100 GeV. Measurements of isolated-photon plus jet cross sections are presented as functions of the leading-photon transverse energy, the leading-jet transverse momentum, the azimuthal angular separation between the photon and the jet, the photon–jet invariant mass and the scattering angle in the photon–jet centre-of-mass system. Tree-level plus parton-shower predictions from Sherpa and Pythia as well as next-to-leading-order QCD predictions from Jetphox and Sherpa are compared to the measurements

A search for resonances decaying into a Higgs boson and a new particle X in the XH → qqbb final state with the ATLAS detector

A search for heavy resonances decaying into a Higgs boson (H) and a new particle (X) is reported, utilizing 36.1 fb−1 of proton–proton collision data at collected during 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. The particle X is assumed to decay to a pair of light quarks, and the fully hadronic final state is analysed. The search considers the regime of high XH resonance masses, where the X and H bosons are both highly Lorentz-boosted and are each reconstructed using a single jet with large radius parameter. A two-dimensional phase space of XH mass versus X mass is scanned for evidence of a signal, over a range of XH resonance mass values between 1 TeV and 4 TeV, and for X particles with masses from 50 GeV to 1000 GeV. All search results are consistent with the expectations for the background due to Standard Model processes, and 95% CL upper limits are set, as a function of XH and X masses, on the production cross-section of the resonance