On the Influence of Cortical Bone and Geometric Parameters in the Maxillofacial Micro-Screws used in Orthodontics

2010 ◽  
Author(s):  
J. Marcé-Nogué ◽  
A. Walter ◽  
L. Gil ◽  
A. Puigdollers
Keyword(s):  
Cortical Bone ◽  
Geometric Parameters

scholarly journals Regional differences of densitometric and geometric parameters of the third metacarpal bone in coldblood horses – pQCT study

2017 ◽  
Vol 61 (1) ◽  
pp. 111-120
Author(s):  
Małgorzata Dzierzęcka ◽  
Maciej Jaworski ◽  
Halina Purzyc ◽  
Karolina Barszcz
Keyword(s):  
Bone Mineral Density ◽  
Cortical Bone ◽  
Bone Mineral ◽  
Metacarpal Bone ◽  
Geometric Parameters ◽  
Mineral Density ◽  
Strain Index ◽  
Trabecular Bone Mineral Density ◽  
The Third ◽  
Metaphyseal Region

AbstractIntroduction:The aim of the study was to analyse selected densitometric and geometric parameters in the third metacarpal bone along the long axis in horses. The densitometric parameters included the cortical and trabecular bone mineral density, while the geometric parameters included the cortical, trabecular, and total areas, strength strain index X, strength strain index Y, and the polar strength strain index.Material and Methods:The parameters were analysed using eight sections from 10% to 80% of the length of the bone. Peripheral quantitative computed tomography was used in the study. Statistical analysis was carried out using the Friedman analysis of variance andpost-hoctests.Results:The proximal metaphyseal region showed the highest predicted resistance to bone fractures in the transverse (back-front) plane, the distal metaphyseal region had the highest predicted resistance to transverse and torsional fractures in the transverse (side-side) plane. The cross-sectional area and the shape of the cross-section of the cortical bone of the MCIII had the highest coefficient of variation. The density of the cortical bone was least variable.Conclusions:The cortical area and cortical bone mineral density assumed the highest values in the diaphyseal region, while the highest total area, trabecular area and trabecular bone mineral density values were obtained in the metaphyseal proximal and distal region.

Lectin-Induced RBC Agglutination: Chemical vs. Cryofixation

1980 ◽  
Vol 38 ◽  
pp. 664-665
Author(s):  
Dean A. Handley ◽  
Lanping A. Sung ◽  
Shu Chien
Keyword(s):  
Lectin Binding ◽  
Freeze Substitution ◽  
Electrostatic Charge ◽  
Geometric Parameters ◽  
Comparative Approach ◽  
Chemical Fixation ◽  
Cell Surfaces ◽  
Minimal Cell ◽  
Membrane Stiffness ◽  
Cell Contour

RBC agglutination by lectins represents an interactive balance between the attractive (bridging) force due to lectin binding on cell surfaces and disaggregating forces, such as membrane stiffness and electrostatic charge repulsion (1). During agglutination, critical geometric parameters of cell contour and intercellular distance reflect the magnitude of these interactive forces and the size of the bridging macromolecule (2). Valid ultrastructural measurements of these geometric parameters from agglutinated RBC's require preservation with minimal cell distortion. As chemical fixation may adversely influence RBC geometric properties (3), we used chemical fixation and cryofixation (rapid freezing followed by freeze-substitution) as a comparative approach to examine these parameters from RBC agglutinated with Ulex I lectin.

Pullout Strength of Screws in Foal Third Metacarpal Bone after Overdrilling a 4.5 mm Hole

1998 ◽  
Vol 11 (04) ◽  
pp. 200-204 ◽  
Author(s):  
K. Kelly ◽  
G. S. Martin ◽  
D. J. Burba ◽  
S. A. Sedrish ◽  
R. M. Moore
Keyword(s):  
Cortical Bone ◽  
Metacarpal Bone ◽  
Pullout Strength ◽  
Cancellous Screw ◽  
Bone Screw ◽  
Screw Insertion ◽  
Holding Power ◽  
Cortical Screw ◽  
Metaphyseal Bone

SummaryThe purpose of the study was to determine and to compare the in vitro pullout strength of 5.5 mm cortical versus 6.5 mm cancellous bone screws inserted in the diaphysis and metaphysis of foal third metacarpal (MCIII) bones in threaded 4.5 mm cortical bone screw insertion holes that were then overdrilled with a 4.5 mm drill bit. This information is relevant to the selection of a replacement screw if a 4.5 mm cortical screw is stripped during orthopaedic surgery. In vitro pullout tests were performed in two independent cadaver studies, each consisting of 12 foal MCIII bones. Two 4.5 mm cortical screws were placed either in the mid-diaphysis (study 1) or distal metaphysis (study 2) of MCIII bones. The holes were then overdrilled with a 4.5 mm bit and had either a 5.5 mm cortical or a 6.5 mm cancellous screw inserted; screw pullout tests were performed at a rate of 0.04 mm/s until screw or bone failure occurred.The bone failed in all of the tests in the diaphyseal and metaphyseal bone. The holding power for 6.5 mm cancellous screws was significantly (p <0.05) greater than for 5.5 mm cortical screws in both the diaphysis and metaphysis. There was not any difference in the holding power of screws in either the diaphysis or the metaphysis between proximal and distal screw holes.If a 4.5 mm cortical bone screw strips in MCIII diaphyseal or metaphyseal bone of foals, a 6.5 mm cancellous screw would provide greater holding power than a 5.5 mm cortical screw.In order to provide information regarding selection of a replacement screw if a 4.5 mm cortical screw is stripped, the in vitro pullout strength was determined for 5.5 mm cortical and 6.5 mm cancellous screws inserted in third metacarpal diaphyseal and metaphyseal bone of foals in which threaded 4.5 mm cortical bone screw insertion holes had been overdrilled with a 4.5 mm bit. The holding power of the 6.5 mm cancellous screw was significantly greater than the 5.5 mm cortical screw in both the diaphysis and metaphysis of foal third metacarpal bone. Thus, it appears that if a 4.5 mm cortical screw is stripped during orthopaedic surgery in foals, a 6.5 mm cancellous screw would provide superior holding power.

Glucocorticoid-induced loss of cortical bone is exacerbated during cold-exposure in male mice

2019 ◽  
Author(s):  
M Gado ◽  
M Noll ◽  
A Heinrich ◽  
M Rauner ◽  
LC Hofbauer ◽  
...  
Keyword(s):  
Cortical Bone ◽  
Cold Exposure ◽  
Male Mice
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