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]. Rio de Janeiro (RJ): Federal University of Rio de JaneiroAsmussen, E., Factors affecting the color stability of restorative resins (1983) Acta Odontol Scand., 41 (1), pp. 11-18Tyas, M.J., Colour stability of composite resins: A clinical comparison (1992) Aust Dent J., 37 (2), pp. 88-90Kihn, P.W., Barnes, D.M., Romberg, E., Peterson, B.S., A clinical evaluation of 10 percent vs. 15 percent carbamide peroxide tooth-whitening agents (2000) J Am Dent Assoc., 131 (10), pp. 1478-1484Jones, H.A., Diaz-Arnold, M.A., Vargas, A.M., Cobb, S.D., Colorimetric assessment of laser and home bleaching techniques (1999) J Esthet Dent., 11 (2), pp. 87-94Attia, M.L., Aguiar, F.H.B., Mathias, P., Ambrosano, G.M.B., Fontes, C.M., Liproni, P.C., The effect of coffee solution on tooth color during home bleaching applications (2009) Am J Dent., 22 (3), pp. 175-17

Combination of searches for Higgs boson pairs in pp collisions at \sqrts = 13 TeV with the ATLAS detector

This letter presents a combination of searches for Higgs boson pair production using up to 36.1 fb(-1) of proton-proton collision data at a centre-of-mass energy root s = 13 TeV recorded with the ATLAS detector at the LHC. The combination is performed using six analyses searching for Higgs boson pairs decaying into the b (b) over barb (b) over bar, b (b) over barW(+)W(-), b (b) over bar tau(+)tau(-), W+W-W+W-, b (b) over bar gamma gamma and W+W-gamma gamma final states. Results are presented for non-resonant and resonant Higgs boson pair production modes. No statistically significant excess in data above the Standard Model predictions is found. The combined observed (expected) limit at 95% confidence level on the non-resonant Higgs boson pair production cross-section is 6.9 (10) times the predicted Standard Model cross-section. Limits are also set on the ratio (kappa(lambda)) of the Higgs boson self-coupling to its Standard Model value. This ratio is constrained at 95% confidence level in observation (expectation) to -5.0 &lt; kappa(lambda) &lt; 12.0 (-5.8 &lt; kappa(lambda) &lt; 12.0). In addition, limits are set on the production of narrow scalar resonances and spin-2 Kaluza-Klein Randall-Sundrum gravitons. Exclusion regions are also provided in the parameter space of the habemus Minimal Supersymmetric Standard Model and the Electroweak Singlet Model. For complete list of authors see http://dx.doi.org/10.1016/j.physletb.2019.135103</p

Searches for lepton-flavour-violating decays of the Higgs boson in s=13\sqrt{s}=13 TeV pp\mathit{pp} collisions with the ATLAS detector

This Letter presents direct searches for lepton flavour violation in Higgs boson decays, H → eτ and H → μτ , performed with the ATLAS detector at the LHC. The searches are based on a data sample of proton–proton collisions at a centre-of-mass energy √s = 13 TeV, corresponding to an integrated luminosity of 36.1 fb−1. No significant excess is observed above the expected background from Standard Model processes. The observed (median expected) 95% confidence-level upper limits on the leptonflavour-violating branching ratios are 0.47% (0.34+0.13−0.10%) and 0.28% (0.37+0.14−0.10%) for H → eτ and H → μτ , respectively.publishedVersio

Search for flavour-changing neutral currents in processes with one top quark and a photon using 81 fb⁻¹ of pp collisions at \sqrts = 13 TeV with the ATLAS experiment

A search for flavour-changing neutral current (FCNC) events via the coupling of a top quark, a photon, and an up or charm quark is presented using 81 fb−1 of proton–proton collision data taken at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Events with a photon, an electron or muon, a b-tagged jet, and missing transverse momentum are selected. A neural network based on kinematic variables differentiates between events from signal and background processes. The data are consistent with the background-only hypothesis, and limits are set on the strength of the tqγ coupling in an effective field theory. These are also interpreted as 95% CL upper limits on the cross section for FCNC tγ production via a left-handed (right-handed) tuγ coupling of 36 fb (78 fb) and on the branching ratio for t→γu of 2.8×10−5 (6.1×10−5). In addition, they are interpreted as 95% CL upper limits on the cross section for FCNC tγ production via a left-handed (right-handed) tcγ coupling of 40 fb (33 fb) and on the branching ratio for t→γc of 22×10−5 (18×10−5). © 2019 The Author(s

Mapping density, diversity and species-richness of the Amazon tree flora

Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution

Consistent patterns of common species across tropical tree communities

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees