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The calcium complexation and acid–base properties of α-d-isosaccharinate (Isa−) in neutral and in (hyper)alkaline solutions have been investigated via potentiometric titrations, multinuclear NMR, ESI-MS and quantum chemical calculations. Isa− is the primary alkaline degradation product of cellulose, and may be present in radioactive waste repositories and therefore, it could contribute to the mobilization of radioactive nuclei. Because of its limited availability, d-gluconate (Gluc−) is commonly used as a structural and functional model of Isa−. Therefore, the thermodynamic and structural data obtained for Isa− were compared with those of Gluc−. The formation constants of the CaIsa+ and CaGluc+ complexes present in neutral solutions are practically identical, but the binding sites are in different positions and the CaIsa20 solution species cannot be detected. The stepwise formation constant of the CaIsaH−10 complex (forming in alkaline medium) is somewhat larger than that of CaGlucH−10, which is in line with the observation that IsaH−12− is a stronger base than GlucH−12−. The most striking difference is that, unlike Gluc−, Isa− does not form polynuclear complexes with Ca2+. The structural reason for this is that the alcoholate groups on C2 and C3 adjacent to the carboxylate moiety on Gluc− are able to simultaneously bind Ca2+, making the formation of polynuclear Ca-complexes possible. On Isa−, only the alcoholate on C2 is involved, while the other one on C6 is not (supposedly for steric reasons). In conclusion, during the interactions of Gluc− and Isa− with Ca2+, differences rather than similarities prevail. [ABSTRACT FROM AUTHOR]

Background: Measurement-based studies are prone to measurement errors, which occur at the same operator or between different operators during repeated measurements of the same sample.

Background: The need for the whitening effects of toothpastes became primary for most users. Changes in the surface roughness of restoration materials after tooth brushing are inevitable, and the abrasion is known to increase the possibility of dental plaque accumulation. Aim of the study: To evaluate in vitro surface roughness changes of different dental restorative materials after tooth brushing simulation. Material and methods: Fifty specimens of two composite materials (Evicrol, Super-Cor), two glass ionomer materials (Glassfill, Kavitan Cem) and a silicate cement (Fritex) were prepared according to the manufacturer’s instructions. Each group of specimens was divided in three subgroups for tooth brushing simulation: using two different types of toothpaste and without toothpaste. Before and after 153 hours of tooth brushing simulation with a custom-made device, the surface roughness was measured with a surface roughness tester. Statistical analysis was performed after collecting the data. Results: All materials exhibited changes in surface roughness after the use of both toothpastes. The self-curing composite showed the less change and glass ionomer materials showed the greatest changes in surface roughness. Conclusions: The surface changes of dental materials depended on their composition and the cleaning procedure. Although self-curing composite was the most resistant to surface changes, its surface roughness values were high. Light-curing composite presented the lowest surface roughness values, even after brushing with toothpastes. The “medium” labeled toothbrush caused significant changes without toothpaste on the surface of light-curing composite, glass ionomer and silicate cement materials.

The identification and exploration of genetic loci that influence smoking behaviors have been conducted primarily in populations of the European ancestry. Here we report results of the first genome-wide association study meta-analysis of smoking behavior in African Americans in the Study of Tobacco in Minority Populations Genetics Consortium (n=32 389). We identified one non-coding single-nucleotide polymorphism (SNP; rs2036527[A]) on chromosome 15q25.1 associated with smoking quantity (cigarettes per day), which exceeded genome-wide significance (\(\beta\)=0.040, s.e.=0.007, P=1.84 × 10\(^{−8}\)). This variant is present in the 5′-distal enhancer region of the CHRNA5 gene and defines the primary index signal reported in studies of the European ancestry. No other SNP reached genome-wide significance for smoking initiation (SI, ever vs never smoking), age of SI, or smoking cessation (SC, former vs current smoking). Informative associations that approached genome-wide significance included three modestly correlated variants, at 15q25.1 within PSMA4, CHRNA5 and CHRNA3 for smoking quantity, which are associated with a second signal previously reported in studies in European ancestry populations, and a signal represented by three SNPs in the SPOCK2 gene on chr10q22.1. The association at 15q25.1 confirms this region as an important susceptibility locus for smoking quantity in men and women of African ancestry. Larger studies will be needed to validate the suggestive loci that did not reach genome-wide significance and further elucidate the contribution of genetic variation to disparities in cigarette consumption, SC and smoking-attributable disease between African Americans and European Americans.

Background: The purpose of this study was to investigate the effect of different light curing modes on the polymerization shrinkage of a bulk-fill composite and to evaluate the impact of two layering techniques on the cuspal deflection., Methods: Nine different light curing modes were tested on bulk-fill composite samples in aluminum MOD cavities. Intensity, duration, and illumination distance were the factors that changed during the different curing modes. The digital image correlation method was used to visually represent the displacement of carbon particles on the materials' surface caused by shrinkage along both the horizontal and vertical axes. For simulating cuspal deflection, a separate protocol was used, with a bulk and horizontal layering technique., Results: The results showed that the largest horizontal displacements were present in the soft start group (6.00 ± 0.82 µm) and in the X-tra power group (5.67 ± 1.21 µm). The smallest horizontal displacements were detected in normal curing modes (4.00 ± 1.58 µm; 4.00 ± 2.68 µm). The largest vertical displacements, at the bottom layer, were present in the normal curing mode group with a 20 s curing time (5.22 ± 1.56 µm), while the smallest vertical displacements were shown in the X-tra power group (2.89 ± 0.60 µm). The observed particle displacements showing the shrinkage of the composite were correlated with the curing mode. The bulk-fill group showed less cuspal deflection than the horizontal layering group did, but the difference was not statistically significant ( p = 0.575)., Conclusions: Within the limitations of this in vitro study, it can be concluded that lower intensities of curing lights (1200 mW/cm 2 ) may perform better from the point of view of material shrinkage than high and extreme light intensities do. The pulse delay mode might be recommended in the case of bulk-fill materials. The number of layers did not significantly affect the cuspal deflection in the case of the studied composite.

Background: Bracket failure increases the treatment time of orthodontic therapy and burdens patients with unnecessary costs, increased chair time, and possible new appointments., Objective: To compare the bond failures of different orthodontic materials based on the results of available clinical studies., Search Methods: A systematic search of clinical trials was performed in the Cochrane, Embase, and Pubmed databases with no limitations. The list of investigated techniques contained conventional acid-etch primer (CM-AEP), self-etch primer (SEP), self-cure resin (SCR), and simple or resin-modified glass ionomer (RM-GIC) materials and procedures., Selection Criteria: Clinical studies reporting the failure rate of bonded brackets after using direct adhesive techniques on buccal sites of healthy teeth were included., Data Collection and Analysis: Bracket failure rates from eligible studies were extracted by two authors independently. Risk ratios (RRs) were pooled using the random-effects model with DerSimonian-Laird estimation., Results: Thirty-four publications, involving 1221 patients, were included. Our meta-analysis revealed no significant difference in the risk of bracket failures between SEP and CM-AEP. After 6, 12, and 18 months of bonding, the values of RR were 1.04 [95% confidence interval (CI), 0.67-1.61], 1.37 (95% CI, 0.98-1.92), and 0.93 (95% CI, 0.72-1.20), respectively. At 18 months, bracket failure was 4.9 and 5.2% for SEP and CM-AEP, respectively. Heterogeneity was good or moderate (I2 < 42.2%). The results of RM-GIC at 12 months indicated a 57% lower risk of bracket failure using SCR as compared with RM-GIC (RR: 0.38; 95% CI, 0.24-0.61). At 18 months, bracket failures for SCR and RM-GIC were 15.8 and 36.6%, respectively (RR: 0.44; 95% CI, 0.37-0.52, I2 = 78.9%), demonstrating three to six times higher failure rate than in the case of etching primer applications., Limitations: A major limitation of the present work is that the included clinical trials, with no exceptions, showed variable levels of risk of bias. Another possible problem affecting the outcome is the difference between the clustering effects of the split mouth and the parallel group bracket allocation methods., Conclusions and Implications: The results revealed no significant difference between SEP and CM-AEP up to 18 months after application. RM-GIC had much worse failure rates than acid-etching methods; additionally, the superiority of SCR over RM-GIC was evident, indicating strong clinical relevance., Registration: Prospero with CRD42020163362., (© The Author(s) 2022. Published by Oxford University Press on behalf of the European Orthodontic Society.)

Sodium citrate (Na 3 Cit) has a crucial role in many biological and industrial processes. Yet, quantitative information on its hydration and the ion association between Na + and Cit 3- ions in a broad range of salt concentrations is still lacking. In this work, we study both ion association equilibria and relaxation dynamics of sodium citrate solutions by combining potentiometry, spectrophotometry, and dielectric spectroscopy. From photometric and potentiometric measurements, we detect the formation of the NaCit 2- ion-pair and the neutral Na 3 Cit 0 ion aggregate in a wide range of ionic strengths (0.5-4 M). Due to its remarkable stability, the latter becomes the prevailing species at higher salt concentrations. In the dielectric spectra, we observe the dipolar relaxation of Cit 3- and NaCit 2- and two solvent-related processes, associated with the collective rearrangement of the H-bond network (cooperative water mode) and the H-bond flip of water molecules (fast water mode). Unlike numerous other salt solutions, the relaxation time of the cooperative mode scales with the viscosity indicating that the strongly hydrated anion fits well into the water network. That is, the stabilizing effect of anion-solvent interactions on the H-bond network outweighs the destructive impact of the cations as the latter are only present at low concentration, due to strong ion association. In conclusion, the affinity of citrate toward Na + binding not only governs solution equilibria but also has a strong impact on water dynamics.

The complexation equilibria between Mg 2+ and d-gluconate (Gluc - ) ions are of particular importance in modeling the chemical speciation in low- and intermediate-level radioactive waste repositories. NMR measurements and potentiometric titrations conducted at 25 °C and 4 M ionic strength revealed the formation of the MgGluc + , MgGlucOH 0 , MgGluc(OH) 2 - , and Mg 3 Gluc 2 (OH) 4 0 complexes. The trinuclear species provides indirect evidence for the existence of multinuclear magnesium(II) hydroxido complexes, whose formation was proposed earlier but has not been confirmed yet. Additionally, speciation calculations demonstrated that MgCl 2 can markedly decrease the solubility of thorium(IV) at low ligand concentrations. Regarding the structure of MgGluc + , both IR spectra and density functional theory (DFT) calculations indicate the monodentate coordination of Gluc - . By the potentiometric data, the acidity of the water molecules is higher in the MgGluc + and MgGlucOH 0 species than in the Mg(H 2 O) 6 2+ aqua ion. On the basis of DFT calculations, this ligand-promoted hydrolysis is caused by strong hydrogen bonds forming between Gluc - and Mg(H 2 O) 6 2+ . Conversely, metal-ion-induced ligand deprotonation takes place in the case of calcium(II) complexes, giving rise to salient variations on the NMR spectra in a strongly alkaline medium.

Introduction: Teeth, as an integral part of human organism, are not exceptions from the physical anthropology changes caused by biological evolution and the way of living. Different stress factors and the natural selection are contributing to the emphasis of certain morphological characteristics., Aim: Comparison of dental metric characteristics and the presence of accessory tooth cusps between human remains from the Middle Ages and dental study models of today's patients., Material and Method: Morphological characteristics of 132 teeth from 19 skulls and 694 teeth on dental models of 30 patients were examined. The mesiodistal, incisivocervical and buccolingual diameters of crowns were measured by a validated 2D image analysis method. Carabelli and talon cusps were also examined using a magnifying glass., Results: Statistically significant differences between the size of the 14th-century and the present-day teeth were found in some of the teeth groups. In medieval artifacts, lateral teeth had smaller crown width than teeth measured in the contemporary population. The Carabelli cusps found in the archeological human remains belonged to grades 1 and 3 on Dahlberg scale (23.07%), while the Carabelli cusps observed in the contemporary group belonged to grades 3, 4, 5, 6 and 7 (50.90%). Talon cusp occurred only once in the contemporary group., Conclusion: In case of the contemporary teeth, the Carabelli cusps appeared in a more pronounced morphological form and with a higher frequency, which emphasizes the European origin of today's population. Orv Hetil. 2018; 159(30): 1235-1240.

The calcium sugar carboxylate interactions in hyperalkaline solutions are of relevance in radioactive waste repositories and in certain industrial processes. The complex formation between L-gulonate and Ca 2+ ions was studied in strongly alkaline medium at 25 °C and 1 M ionic strength and was compared with previous results reported for D-gluconate and D-heptagluconate. The deprotonation of the ligand was confirmed by potentiometric and 13 C NMR spectroscopic measurements. Pronounced pH effects were seen in the presence of Ca 2+ indicating strong complex formation. By the evaluation of the experimental data, two highly stable trinuclear species, Ca 3 Gul 2 H -3 + and the Ca 3 Gul 2 H -4 0 , are formed in alkaline aqueous solutions. Polarimetric as well as 1 H NMR spectroscopic measurements attested that the increased complex stability was due to the formation of strong metal ion - alcoholate interactions. Moreover, the 1 H NMR spectra of the three anions refer to the role of configuration in metal ion-binding. That is, the participation of the C3-OH or C4-OH group is governed by the relative position (i.e., threo or erythro) of the C2-OH and C3-OH groups., (Copyright © 2018 Elsevier Ltd. All rights reserved.)