Search results for "cortical bone"

Radiological implications of crestal and subcrestal implant placement in posterior areas. A cone-beam computed tomography study

2020

Background Subcrestal implant placement has been suggested as a method that could contribute to maintain the periimplant soft and hard tissues in comparison with crestal placement. The objective of this study was to investigate the relationship between implant placement at different depths in the alveolar bone and (a) the thickness of the buccal bone plate (BBP); and (b) crestal cortical bone thickness, based on the use of cone-beam computed tomography (CBCT). Material and Methods A cross-sectional study was performed, analyzing CBCT scans from the database of the Oral Surgery Unit of the University of Valencia. Individuals with single missing teeth in posterior sectors were included. Two t…

Dentoalveolar changes in adults promoted by the use of auxiliary expansion arch: A CBCT study

2019

Background The objective of this study was to evaluate the dentoalveolar effects and the changes of buccal cortical bone in the posterior area after expansion obtained with TMA auxiliary expansion arch in adult patients. Material and Methods A retrospective analysis of CT scans of 13 patients (6 male, 7 female) treated at a private clinic, taken immediately before and after the use of an auxiliary expansion archwire, was performed. Mean age at installation of TMA auxiliary expansion arch was 29.23 years (s.d.=9.13) and the mean age when the auxiliary arch was removed was 29.52 years (s.d.=9.16). Mean time of the use of the TMA auxiliary expansion arch was 0.29 years (s.d.=0.09). The patient…

Assessment of the fundamental flexural guided wave in cortical bone by an ultrasonic axial-transmission array transducer

2013

Abstract The fundamental flexural guided wave (FFGW), as modeled, for example, by the A0 Lamb mode, is a clinically useful indicator of cortical bone thickness. In the work described in this article, we tested so-called multiridge-based analysis, based on the crazy climber algorithm and short-time Fourier transform, for assessment of the FFGW component recorded by a clinical array transducer featuring a limited number of elements. Methods included numerical finite-element simulations and experiments in bone phantoms and human radius specimens ( n  = 41). The proposed approach enabled extraction of the FFGW component and determination of its group velocity. This group velocity was in good ag…

Architecture in cortical bone and ultrasound transmission velocity

1993

The square of ultrasound transmission velocity in a material is correlated to the modulus of elasticity, which is an indicator of its mechanical properties. This might make the measurement of ultrasound transmission velocity useful in the noninvasive diagnosis of bone diseases. Bone, however, is not an isotropic material but is architecturally structured. The aim of our study was to investigate and especially to quantify the influence of architecture in cortical bone on ultrasound transmission velocity. Twenty-two rectangular, flat specimens of cortical bone were prepared from diaphysis of fresh pig radius. Ultrasound transmission velocity was measured parallel and perpendicular to directio…

Progressive femoral cortical and cancellous bone density loss after uncemented tapered-design stem fixation

2010

Background Aseptic implant loosening and periprosthetic bone loss are major problems after total hip arthroplasty (THA). We present an in vivo method of computed tomography (CT) assisted osteodensitometry after THA that differentiates between cortical and cancellous bone density (BD) and area around the femoral component.Method Cortical and cancellous periprosthetic femoral BD (mg CaHA/mL), area (mm2) and contact area between the prothesis and cortical bone were determined prospectively in 31 patients 10 days, 1 year, and 6 years after uncemented THA (mean age at implantation: 55 years) using CT-osteodensitometry.Results 6 years postoperatively, cancellous BD had decreased by as much as 41%…

Influence of Different Rehydration Protocols on Biomechanical Properties of Allogeneic Cortical Bone Plates: A Combined in-vitro/in-vivo Study

2020

Introduction: Allogeneic cortical bone plates (CP) are used for alveolar ridge augmentation. Since CP are freeze-dried and dehydrated during processing, the breaking strength (BS) and the flexibility (FX) are reduced, resulting in a relevant risk for plate fractures during insertion. The aim of this study was to evaluate the influence of rehydration time on the biomechanical properties (BS & FX) of CP in-vitro and in vivo.Material and Methods: 40 CP were randomly divided into four experimental groups. (A) untreated control (n = 10), rehydration for 10 (B), 30 (C) and 60 (D) minutes in 0.9% saline solution (n = 10 each). BS [Newton, N] and FX [mm] (force till fracture and distance of deflect…

Tailoring the excitation of fundamental flexural guide waves in coated bone by phase-delayed array: Two-dimensional simulations

2015

The fundamental flexural guided wave (FFGW) enables ultrasonic assessment of cortical bone thickness. In vivo, it is challenging to detect this mode, as its power ratio with respect to disturbing ultrasound is reduced by soft tissue covering the bone. A phase-delayed ultrasound source is proposed to tailor the FFGW excitation in order to improve its power ratio. This situation is analyzed by 2D finite-element simulations. The soft tissue coating (7-mm thick) was simulated as a fluid covering an elastic plate (bone, 2–6 mm thick). A six-element array of emitters on top of the coating was excited by 50-kHz tone bursts so that each emitter was appropriately delayed from the previous one. Respo…

Ultrasound measurements in bone using an array transducer

2014

Autogreffe chondrocostale pour lésion latérale ostéochondrale de la tête métacarpienne

2020

Abstract Osteochondral injuries of the metacarpal head require anatomical restoration to prevent limitations in range of motion and osteoarthritis. Osteochondral bone grafting is a viable option, especially in younger patients. Central injuries allow for different types of grafting, but when the injured area is on the lateral portion of the metacarpal head, the graft must include both a cortical and a cartilaginous portion. We present here the pearls and pitfalls in the surgical technique of chondrocostal grating from the 6th rib and an example of its use within a case of comminuted fracture of the metacarpal head. This technique provides a graft with cortical bone that allows for a stable …

Impact of estrogens on atherosclerosis and bone in the apolipoprotein E-deficient mouse model.

2014

Objective The common inflammatory pathophysiology has nourished the hypothesis of a relationship between osteoporosis and cardiovascular disease. Estrogens are key agents in the modulation of both processes. We investigated whether induction of atherosclerosis affects bone and whether estrogens modulate both processes. Methods Female apolipoprotein E-deficient mice (a well-established model of atherogenesis) were ovariectomized or falsely operated and fed either standard diet or high-fat diet (HFD). Six animals were included in each of the four groups. To clarify mechanisms, we treated preosteoblastic MC3T3-E1 cells with mouse serum. Results Physiological levels of estrogens in falsely oper…