[Finite element analysis of the effect of plate placement angle on cervical spine stability in anterior cervical fusion surgery].

OBJECTIVE: Using the method of finite element analysis, to compare the biomechanical properties between the plate deviating from the long axis of the cervical spine and the standard placement of the plate in the anterior cervical fusion surgery. METHODS: A healthy female volunteer was selected and CT scan (C1-T1) was performed. Using Mimics 19.0, Geomagic Studio 2015, Solidworks 2018, Ansys Workbench 17.2 to establish a lower cervical spine (C3-C7) model and to verify the reliability of the model. Subsequently, anterior cervical plates of different angles and lengths were placed to establish an anterior cervical discectomy fusion (ACDF) model. Applying 73.6 N axial pressure and 1 NM pure moment on C3 to make the model produce flexion, extension, lateral bending and rotation activities, observed the model stress cloud diagram and recorded the maximum stress value of the instrument and the intervertebral mobility. RESULTS: The lower cervical spine (C3-C7) finite element model was established and verified against the published literature on the range of motion (ROM) of cervical spine. Effect of steel plate offset axis on stress distribution, maximum stress value and intervertebral ROM of internal fixation apparatus was minimal, and the mechanical effect of steel plate offset was less in double section steel plate than in single section steel plate. CONCLUSION: Little effect on the mechanical stability of the cervical spine was anticipated when the anterior cervical plate was not perfectly aligned with the long axis of the cervical spine. If the tilt of the plate in clinical surgery is less than 20°, there is no need to readjust the position of the plate.

Protraction of mandibular molars through a severely atrophic edentulous space in a case of juvenile periodontitis.

Moving the mandibular posterior teeth into a severely atrophic edentulous space is a challenge. A carefully designed force-and-moment system that results in bodily protraction of the posterior teeth with balanced bone resorption and apposition is needed in such cases. This report describes the treatment of a 19-year-old woman with missing mandibular first molars due to juvenile periodontitis. Miniscrews were used as absolute anchorage during protraction of the mandibular second and third molars. Bodily mesial movement of the mandibular second and third molars was achieved over a distance of 11 to 17 mm after 39 months of orthodontic treatment.

[A pilot study on the accuracy of digital model reconstructed by cone beam CT].

PURPOSE: To study the feasibility of digital model produced by cone beam CT. METHODS: Ten patients seeking orthodontic treatment with congested lower incisors were enrolled in this study. Plaster models of the lower arch were made using routing method. Digital model was reconstructed from these plaster models by NewTom 3G cone beam CT with 6 inch model. Linear measurements including right first premolar width, arch width, arch length, right first incisor width, all incisors and canines width, were done on the lower arch on plaster models with calipers. The same measurements on digital model were made using software Simplant Pro11.04. Linear measurements were repeated one week later on both plaster and digital model. Paired t test was used to determine the difference between the linear measurements on both models. The absolute measurements errors of two models were compared using paired t test. All statistical analysis was performed using SPSS13.0 software package. RESULTS: The linear measurements of the digital model slightly underestimated the real plaster model, but no significant difference of the linear measurements was seen between the plaster model and the digital model. The value of all of the lower incisors and canines width of plaster models was significantly higher than that of digital model. Mean absolute difference of different measurement of digital model was not significant from that of plaster model. CONCLUSION: Digital model using CBCT is feasible for the linear measurement and storage.

Trinuclear and mononuclear copper(II) complexes incorporating tetradentate 2,2'-[1,1'-(ethylenedioxydinitrilo)diethylidyne]diphenol ligand: Syntheses, crystal structures, spectral and thermal behaviors.

Mononuclear and trinuclear Cu(II) complexes with chemical formula [CuL].CH3OH (1) and [{(Cu(mu-L))2(OAc)2}Cu] (2), where H2L = 2,2'-[1,1'-(ethylenedioxydinitrilo)diethylidyne]diphenol, have been synthesized and characterized by elemental analyses, 1H NMR, IR and UV-vis spectra et al. Crystallographic data of complex 1 reveal the formation of an asymmetric mononuclear structure and a slight distortion toward tetrahedral geometry from the square planar structure, in which the introduction of the non-coordinated methanol molecule lead to the assembly of the 1D chains by hydrogen bonding, Cu...pi and pi...pi interactions. Complex 2 have the elongated square pyramidal geometries for the two terminal Cu(II) ions and an octahedral coordinated geometry for the central Cu(II) ion. In complex 2, two acetate ions coordinate to three Cu(II) ions adopting a familiar syn-syn (muM-O-C-O-M) coordinated fashion. The central Cu(II) ion sits in a crystallographic inversion centre. Therefore, the whole molecule of complex 2 is rigorously centrosymmetric, and forms a 3D supramolecular networks through intermolecular C-H...O and C-H..pi interactions.

4-Bromo-2-({4-[(hy-droxy-imino)-meth-yl]phen-yl}imino-meth-yl)phenol.

In the title compound, C(14)H(11)BrN(2)O(2), the mean planes of the two benzene rings are almost parallel to each other, making a dihedral angle of 4.09 (1)°. An intra-molecular O-H⋯N hydrogen bond occurs. In the crystal, inter-molecular O-H⋯N and C-H⋯O hydrogen bonds link the mol-ecules into a chain-like supra-molecular structure.

Bis{(E)-2-[(2-chloro-3-pyrid-yl)imino-meth-yl]-6-meth-oxy-phenolato-κN,O}copper(II).

In the title mononuclear copper(II) complex, [Cu(C(13)H(10)ClN(2)O(2))(2)], the Cu(II) ion, lying on an inversion center, is four-coordinated in a trans-CuN(2)O(2) square-planar geometry by two phenolate O and two imino N atoms from two symmetry-related N,O-bidentate Schiff base ligands. The shortest Cu⋯Cu distance is 7.5743 (9) Å. However, there are weak intra-molecular electrostatic inter-actions between the Cu atom and the Cl atom of the ligand, with a Cu⋯Cl distance of 3.3845 (9) Å.

Bis{(E)-2-[1-(eth-oxy-imino)-eth-yl]-1-naphtho-lato-κN,O}copper(II).

In the title complex, [Cu(C(14)H(14)NO(2))(2)], the discrete complex mol-ecules have crystallographic inversion symmetry. The slightly distorted square-planar coordination sphere of the Cu(II) atom comprises two phenolate O atoms and two oxime N atoms from two bidentate-chelate 2-[1-(eth-oxy-imino)-eth-yl]-1-naphtho-late O-ethyl oxime (L(-)) ligands [Cu-O = 1.8919 (17) Šand Cu-N = 1.988 (2) Å]. The two naphthalene ring systems in the mol-ecule are parallel, with a perpendicular inter-planar spacing of 1.473 (2) Å, while each complex unit forms links to four other mol-ecules via inter-molecular methyl C-H⋯π inter-actions, giving an infinite cross-linked layered supra-molecular structure.

Lower incisor intrusion with intraoral transosseous stainless steel wire anchorage in rabbits.

The purpose of this research was to investigate the potential use of intraoral transosseous stainless steel wires as anchorage for intrusion of the lower incisors using a rabbit model. Placement of intraoral transosseous stainless steel wires around incisors is similar to that of intraoral transosseous wiring of edentulous mandibular fractures. Ten male New Zealand rabbits, 9 +/- 1.5 months of age, average weight 1.8 +/- 0.3 kg, were used in this study. One lower incisor was intruded with a 50 g bilateral force using a coil spring for 10 weeks, while the other incisor served as the control. Clinical measurements of the distances between the occlusal edges of the incisors (EE) were performed weekly with a calliper. In addition to standard descriptive statistical calculations, a paired Student's t-test was used for comparison of the two groups. All surgical sites healed uneventfully after insertion of the wires. Significant differences were found in the change of EE between the experimental and control sides from 4 weeks onwards. Intrusion of the incisor, 4 +/- 0.58 mm, was seen on the test side, while EE on the control side remained unchanged. Within the limits of this animal study, it is concluded that the intraoral transosseous stainless steel wire anchorage system is a cost-effective method for intrusion of lower incisors when the use of other anchorage system is not possible.

2,2'-[1,1'-(Octane-1,8-diyldioxy-dinitrilo)diethyl-idyne]diphenol.

The title compound, C(24)H(32)N(2)O(4), has a crystallographic inversion centre at the mid-point of the central C-C bond. At each end of the mol-ecule, intra-molecular O-H⋯N hydrogen bonds generate six-membered S(6) ring motifs. The crystal structure is stabilized by pairs of weak inter-molecular C-H⋯O hydrogen bonds that link neighbouring mol-ecules into R(2) (2)(40) ring motifs, which in turn form infinite one-dimensional supra-molecular ribbon structures.

4-[1-(Hydroxy-imino)ethyl]-N-(4-nitro-benzyl-idene)aniline.

In the title compound, C(15)H(13)N(3)O(3), the dihedral angle formed by the two benzene rings is 44.23 (2)°. The crystal structure is stabilized by aromatic π-π stacking inter-actions, with centroid-centroid distances of 3.825 (3) and 3.870 (4) Šbetween the aniline and the nitro-benzene rings of neighbouring mol-ecules, respectively. In addition, the stacked mol-ecules exhibit inter-molecular C-H⋯N and C-H⋯O inter-actions.

Bis[(E)-4-bromo-2-(ethoxy-imino-meth-yl)phenolato-κN,O]copper(II).

The title compound, [Cu(C(9)H(9)BrNO(2))(2)], is a centrosymmetric mononuclear copper(II) complex. The Cu atom is four-coordinated in a trans-CuN(2)O(2) square-planar geometry by two phenolate O and two oxime N atoms from two symmetry-related N,O-bidentate (E)-4-bromo-2-(ethoxy-imino-meth-yl)phenolate oxime-type ligands. An inter-esting feature of the crystal structure is the centrosymmetric inter-molecular Cu⋯O inter-action [3.382 (1) Å], which establishes an infinite chain structure along the b axis.

(E)-2-{4-[1-(Hydroxyimino)ethyl]phenyl-iminomethyl}-6-methoxyphenol mono-hydrate.

In the title compound, C(16)H(16)N(2)O(3)·H(2)O, the benzene rings are nearly coplanar with each other, forming a dihedral angle of 4.46 (3)°. There is a strong intra-molecular O-H⋯N hydrogen bond which results in a six-membered ring. In the crystal, the mol-ecules are connected into a three-dimensional network via O-H⋯O and O-H⋯N inter-molecular hydrogen bonds, forming a centrosymmetric ring along the b axis with graph-set motif R(4) (4)(10). In addition, the short distances between the centroids of six-membered rings [3.555 (1) Å], indicate the existence of π-π stacking inter-actions, which may stabilize the crystal structure.

5,5'-Dimeth-oxy-2,2'-[(nonane-1,9-diyldi-oxy)bis-(nitrilo-methyl-idyne)]diphenol.

The mol-ecule of the title compound, C(25)H(34)N(2)O(6), adopts a fully extended configuration. The oxime (-CH=N-O-) group is coplanar with the aromatic ring and the two benzene rings are almost parallel, making a dihedral angle of 0.16 (3)°. In the crystal structure, strong intra-molecular O-H⋯N hydrogen bonds generate six-membered S(6) ring motifs. Inter-molecular C-H⋯O hydrogen bonds link each mol-ecule to five others, forming an infinite three-dimensional supra-molecular structure. The crystal is further stabilized by π-π stacking inter-actions between neighbouring benzene rings [centroid-centroid distance = 3.744 (2) Å].

1,3-Bis[(4-methylbenzylidene)amino-oxy]propane.

The title bis-oxime compound, C(19)H(22)N(2)O(2), synthesized by the reaction of 4-methyl-2-hydroxy-benzaldehyde with 1,3-bis-(amino-oxy)propane in ethanol, adopts a V-shaped conformation. The dihedral angle between the rings is 84.59 (3)°. The mol-ecule is disposed about a crystallographic twofold rotation axis, with one C atom lying on the axis. In the crystal, mol-ecules are packed by C-H⋯π(Ph) inter-actions, forming chains.

2,2'-[Octane-1,8-diyldioxy-bis(nitrilo-methyl-idyne)]diphenol.

The complete mol-ecule of the title compound, C(22)H(28)N(2)O(4), is generated by a crystallographic inversion centre at the mid-point of the central C-C bond. The two benzene rings are parallel to each other with a perpendicular inter-planar spacing of 1.488 (2) Å. Intra-molecular O-H⋯N hydrogen bonds generate two six-membered rings with S(6) motifs. In the crystal, weak inter-molecular C-H⋯O hydrogen bonds link neighbouring mol-ecules into an infinite three-dimensional network, which is further stabilized by weak C-H⋯π inter-actions.

{2,2'-[1,1'-(Ethyl-enedioxy-dinitrilo)diethyl-idyne]di-1-naphtholato}copper(II).

The title complex, [Cu(C(26)H(22)N(2)O(4))], is isostructural with its Ni analogue. All intramolecular distances and angles are very similar for the two structures, whereas the packing of the molecules, including C-H⋯O and C-H⋯π interactions, are slightly different.

{2,2'-[1,1'-(Ethyl-enedioxy-dinitrilo)diethyl-idyne]di-1-naphtholato}nickel(II).

In the title complex, [Ni(C(26)H(22)N(2)O(4))], the Ni(II) atom has a slight distortion toward tetra-hedral geometry from a square-planar structure, coordinated by two O and two N atoms of the tetra-dentate salen-type bis-oxime 2,2'-[1,1'-(ethyl-enedioxy-dinitrilo)diethyl-idyne]di-1-naphtholate (L(2-)) unit, with a mean deviation of 0.022 Šfrom the N(2)O(2) plane. The N- and O-donor atoms are mutually cis. The dihedral angle between two naphthalene systems of the L(2-) ligand is 67.59 (4)°. The crystal structure is stabilized by inter-molecular C-H⋯O and C-H⋯π inter-actions, which link neighbouring mol-ecules into extended chains along the b axis.

2,2'-[1,1'-(Ethyl-enedioxy-dinitrilo)diethyl-idyne]di-1-naphthol.

The complete molecule of the title compound, C(26)H(24)N(2)O(4), is generated by a crystallographic centre of inversion. There are two intra-molecular O-H⋯N hydrogen bonds. In the crystal structure, inter-molecular C-H⋯O hydrogen bonds result in zigzag chains.

2,2'-[1,1'-(Heptane-1,7-diyldioxy-dinitrilo)diethyl-idyne]di-1-naphthol.

The mol-ecule of the title compound, C(31)H(34)N(2)O(4), adopts an L-shaped configuration, in which the naphthalene units are approximately perpendicular, making a dihedral angle of 87.89 (3)°. Intramolecular H-bonds are formed between the OH substituents and the N atoms at each end of the molecule. In the crystal structure, each mol-ecule links six other mol-ecules into an infinite three-dimensional network supra-molecular structure, which is built from one-dimensional zigzag chains via weak C-H⋯π stacking and inter-molecular C-H⋯O hydrogen bonds.

2,2'-[1,1'-(Propane-1,3-diyldioxy-dinitrilo)diethyl-idyne]di-1-naphthol.

The mol-ecule of the title compound, C(27)H(26)N(2)O(4), lies across a crystallographic inversion centre and adopts an l-shaped configuration. Within the mol-ecule, the two naphthalene units are approximately perpendicular, making a dihedral angle of 80.24 (5)°. The two intramolecular O-H⋯N hydrogen bonds, generate S(6) ring motifs. In the crystal structure, every mol-ecule links five other mol-ecules into an infinite cross-linked layered supra-molecular structure via inter-molecular C-H⋯O hydrogen bonds, C-H⋯π inter-actions and π-π stacking inter-actions [centroid-centroid distance = 3.956 (4) Å].