Evaluation of frictional resistance and surface characteristics after immersion of orthodontic brackets and wire in different chemical solutions: A comparative study.

Aim: To evaluate the changes of static and kinetic frictional forces between the brackets and wires following exposure to a soft drink, acidic food ingredient, and acidulated fluoride prophylactic agents.

Materials And Methods: Two types of Roth prescription mandibular incisor brackets were used: 3M Unitek Victory stainless steel (SS) brackets (n = 40) and Transcend 6000 polycrystalline alumina (PCA) brackets (n = 40) as well as eighty 0.019 × 0.

Crystal structures of methyl (E)-3-(2-chloro-phen-yl)-2-({2-[(E)-2-nitro-vin-yl]phen-oxy}meth-yl)acrylate and methyl (E)-2-({4-chloro-2-[(E)-2-nitro-vin-yl]phen-oxy}meth-yl)-3-(2-chloro-phen-yl)acrylate.

The title compounds, C19H16ClNO5, (I), and C19H15Cl2NO5, (II), both crystallize in the monoclinic space group P21/n. They differ essentially in the orientation of the methyl acetate group, with the C=O bond directed towards the NO2 group in (I) but away from it in (II). In compound (I), the mean plane of the methyl acrylate unit is planar, with a maximum deviation of 0.

Crystal structure of 5-(5-chloro-2-hydroxy-benzo-yl)-2-(2-methyl-1H-indol-3-yl)nicotino-nitrile.

In the title compound, C22H14ClN3O2, the indole unit is essentially coplanar, with a maximum deviation of 0.035 Å for the C atom bearing the methyl group. The central pyridine ring is inclined to the indole ring system by 43.

Crystal structure of N-[(4-eth-oxy-phen-yl)carbamo-thio-yl]cyclo-hexa-ne-carboxamide.

The asymmetric unit of the title compound, C16H22N2O2S, contains two crystallographically independent mol-ecules (A and B). In mol-ecule A, the cyclo-hexane ring is disordered over two orientations [occupancy ratio 0.841 (10):0.