[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.

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.

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.

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.

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.

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'-(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].

2,2'-{1,1'-[Butane-1,4-diyl-bis(oxy-nitrilo)]di-ethylidyne}di-1-naphthol.

The title compound, C(28)H(28)N(2)O(4), was synthesized by the reaction of 2-acetyl-1-naphthol with 1,4-bis-(amino-oxy)butane in ethanol. The molecule, which lies about an inversion centre, adopts a linear structure, in which the oxime groups and naphthalene ring systems assume an anti conformation. The intra-molecular inter-planar distance between parallel naphthalene rings is 1.054 (3) Å. Intra-molecular O-H⋯N hydrogen bonds are formed between the oxime nitro-gen and hydr-oxy groups.

Bis{(E)-4-bromo-2-[(2-chloro-3-pyrid-yl)imino-meth-yl]phenolato-κN,O}copper(II).

In the title complex, [Cu(C(12)H(7)BrClN(2)O)(2)], the Cu(II) center is tetra-coordinated by two phenolate O and two azomethine N atoms from two independent bidentate 4-bromo-2-[(2-chloro-3-pyrid-yl)imino-meth-yl]phenolate (L) ligands. In the crystal structure, the Cu(II) atom has a distorted square-planar coordination environment. The inter-planar dihedral angles between the benzene and pyridine rings in the individual ligands are 63.83 (4) and 54.43 (3)°, indicating the pyridine ring to have considerably weaker steric hindrance.

N-Benzoyl-N'-(2-chloro-3-pyrid-yl)thio-urea.

The title compound, C(13)H(10)ClN(3)OS, was prepared by the reaction of 3-amino-2-chloropyridine with benzoyl isothio-cyanate at room temperature. The thio-urea group makes dihedral angles of 47.17 (5) and 51.88 (4)°, respectively, with the benzene and pyridyl rings, while the angle between the benzene and pyridine rings is 8.91 (3)°. Inter-molecular hydrogen-bond inter-actions link neighbouring mol-ecules into an infinite supra-molecular structure.

2,2'-Dichloro-1,1'-[(pentane-1,5-diyldi-oxy)bis-(nitrilo-methyl-idyne)]dibenzene.

The mol-ecule of the title compound, C(19)H(20)Cl(2)N(2)O(2), which lies across a crystallographic inversion centre, adopts a linear configuration. The dihedral angle between the two halves of the mol-ecule is 5.14 (2)°. In the crystal structure, inter-molecular C-H⋯O hydrogen bonds link neighbouring mol-ecules into an infinite zigzag chain supra-molecular structure.