Search results for "Cortical bone"
showing 10 items of 69 documents
Influence of cortical bone and implant design in the primary stability of dental implants measured by two different devices of resonance frequency an…
2020
Background This study aimed to evaluate the effect of the implant design and the presence of cortical bone in the primary stability, as well as analyze the differences between the stability measurements obtained by two different resonance frequency analysis (RFA) devices. Material and methods A total of 80 Klockner implants of two different models [40 Essential Cone implants (group A) and 40 Vega implants (group B)] were used. The implants were placed in two polyurethane blocks that simulated the mechanical properties of the maxillary bone. One block featured a layer of cortical bone that was absent from the other block. The primary stability of all implants was measured by insertion torque…
Comparison of three ultrasonic axial transmission methods for bone assessment.
2005
Abstract This study compared three approaches to bone assessment using ultrasonic axial transmission. In 41 fresh human radii, velocity of the first arriving signal was measured with a commercial device (Sunlight Omnisense ™ ) operating at 1.25 MHz, a prototype based on 1-MHz bidirectional axial transmission and a low-frequency (200 kHz) prototype, also measuring the velocity of a slower wave. Cortical and trabecular bone mineral density, cortical thickness and cross-sectional area were determined by peripheral quantitative computed tomography. Significant but modest correlation between velocities reflects differences in the nature of the propagating waves and methodological differences. Of…
Atlases with Arcuate Foramen Present Cortical Bone Thickening That May Contribute to Lower Fracture Risk.
2018
To date, no information about the cortical bone microstructural properties in atlas vertebrae with arcuate foramen has been reported. As a result, we aimed to test in an experimental model if there is a cortical bone thickening in an atlas vertebra which has an arcuate foramen that may play a protective role against bone fracture.We analyzed by means of micro-computed tomography the cortical bone thickness, the cortical volume, and the medullary volume (SkyScan 1172 Bruker micro-CT NV, Kontich, Belgium) in cadaveric dry atlas vertebrae with arcuate foramen and without arcuate foramen. We also reviewed a case series of 31 posterior atlas arch fractures to correlate the possible presence in t…
Cortical bone thickening in Type A posterior atlas arch defects: experimental report.
2017
Abstract Background Context To date, no information about the cortical bone microstructural properties in atlas vertebrae with posterior arch defects has been reported. Purpose To test if there is an increased cortical bone thickening in atlases with Type A posterior atlas arch defects in an experimental model. Study Design Micro-computed tomography (CT) study on cadaveric atlas vertebrae. Methods We analyzed the cortical bone thickness, the cortical volume, and the medullary volume (SkyScan 1172 Bruker micro-CT NV, Kontich, Belgium) in cadaveric dry vertebrae with a Type A atlas arch defect and normal control vertebrae. Results The micro-CT study revealed significant differences in cortica…
Ameloblastic fibro-odontoma: A conservative surgical approach
2009
Ameloblastic fibro-odontoma (AFO) is a rare benign mixed odontogenic tumor that occurs predominantly in children and young adults with no gender predilection and anatomic site, usually appearing as a painless swelling. We present a case of an 11-year-old non-Caucasian boy complaining of large painless isolated swelling in the right mandibular body. Intraoral examination revealed a tumoral mass with cortical bone expansion, covered by normal mucosa measuring 4.0 x 2.0 cm, located on both the lingual and buccal surfaces of the right body of the mandible, with displacement of the neighboring teeth. Panoramic radiography revealed an expansile, radiolucent and well circumscribed lesion with scat…
Modes of periacetabular load transfer to cortical and cancellous bone after cemented versus uncemented total hip arthroplasty: A prospective study us…
2008
Stress-shielding and periprosthetic bone loss after total hip arthroplasty (THA) may be clinically relevant for high-demand patients. Analysis of cortical and cancellous bone density (BD) changes in vivo after THA is of interest to basic science researchers and joint reconstruction surgeons. An insufficient periprosthetic bone stock may predispose to migration, early mechanical failure, and major problems in revision surgery. We used computed tomography (CT)-assisted osteodensitometry in two prospectively analyzed cohorts after cemented (n = 21) versus noncemented (n = 23) cup fixation. Periacetabular BD (mgCaHa/mL) was determined in five CT scans cranial and five CT scans at the level of t…
Locking plates for corrective osteotomy of malunited dorsally tilted distal radial fractures: a biomechanical study.
2005
The purpose of the study was to compare the biomechanical properties of five different palmar fixation plate designs in a distal radius osteotomy cadaver model. A 1 cm metaphyseal osteotomy gap was made to simulate a corrective osteotomy and the osteotomy plated. Axial load was applied to the distal end of each construct by a material testing machine under control of a motion analysis video system. The specimens were arranged into five implant groups of eight specimens each. No test group developed deformity and movement of the fracture gap greater than 2 mm with a load of 100 N. Increasing the load to 250 N revealed statistically significant differences in stiffness and failure load betwe…
Photo-acoustic excitation and optical detection of fundamental flexural guided wave in coated bone phantoms.
2013
Abstract Photo-acoustic (PA) imaging was combined with skeletal quantitative ultrasound (QUS) for assessment of human long bones. This approach permitted low-frequency excitation and detection of ultrasound so as to efficiently receive the thickness-sensitive fundamental flexural guided wave (FFGW) through a coating of soft tissue. The method was tested on seven axisymmetric bone phantoms, whose 1- to 5-mm wall thickness and 16-mm diameter mimicked those of the human radius. Phantoms were made of a composite material and coated with a 2.5- to 7.5-mm layer of soft material that mimicked soft tissue. Ultrasound was excited with a pulsed Nd:YAG laser at 1064-nm wavelength and received on the s…
Assessment of the cortical bone thickness using ultrasonic guided waves: Modelling and in vitro study
2007
Determination of cortical bone thickness is warranted, e.g., for assessing the level of endosteal resorption in osteoporosis or other bone pathologies. We have shown previously that the velocity of the fundamental antisymmetric (or flexural) guided wave, measured for bone phantoms and bones in vitro, correlates with the cortical thickness significantly better than those by other axial ultrasound methods. In addition, we have introduced an inversion scheme based on guided wave theory, group velocity filtering and 2-D fast Fourier transform, for determination of cortical thickness from the measured velocity of guided waves. In this study, the method was validated for tubular structures by usi…
Measuring guided waves in long bones: Modeling and experiments in free and immersed plates
2005
Guided waves, consistent with the A0 Lamb mode, have previously been observed in bone phantoms and human long bones. Reported velocity measurements relied on line fitting of the observed wave fronts. Such an approach has limited ability to assess dispersion and is affected by interference by other wave modes. For a more robust identification of modes and determination of phase velocities, signal processing techniques using the fast Fourier transform (FFT) were investigated. The limitations of FFT because of spatial resolution were addressed to improve the precision of the measured modes. An inversion scheme was developed for determining the plate thickness from the measured velocity. Experi…