Evaluation of bone formation on orthopedic implant surfaces using an ex-vivo bone bioreactor system

Recent advances in materials and manufacturing processes have allowed the fabrication of intricate implant surfaces to facilitate bony attachment. However, refinement and evaluation of these new design strategies are hindered by the cost and complications of animal studies, particularly during early iterations in the development process. To address this problem, we have previously constructed and validated an ex-vivo bone bioreactor culture system that can maintain the viability of bone samples for an extended period ex-vivo. In this study, we investigated the mineralization of a titanium wire mesh scaffold under both static and dynamic culturing using our ex vivo bioreactor system. Thirty-six cancellous bone cores were harvested from bovine metatarsals at the time of slaughter and divided into five groups under the following conditions: Group 1) Isolated bone cores placed in static culture, Group 2) Unloaded bone cores placed in static culture in contact with a fiber-mesh metallic scaffold, Group 3) Bone cores placed in contact with a fiber-mesh metallic scaffold under the constant pressure of 150 kPa, Group 4) Bone core placed in contact with a fiber-mesh metallic scaffold and exposed to cyclic loading with continuous perfusion flow of media within the ex-vivo culture system and Group 5) Bone core evaluated on Day 0 to serve as a positive control for comparison with all other groups at weeks 4 and 7. Bone samples within Groups 1–4 were incubated for 4 and 7 weeks and then evaluated using histological examination (H&E) and the Live-Dead assay (Life Technologies). Matrix deposits on the metallic scaffolds were examined with scanning electron microscopy (SEM), while the chemical composition of the matrix was measured using energy-dispersive x-ray spectroscopy (EDX). We found that the viability of bone cores was maintained after seven weeks of loading in our ex vivo system. In addition, SEM images revealed crystallite-like structures on the dynamically loaded metal coupons (Group 4), corresponding to the initial stages of mineralization. EDX results further confirmed the presence of carbon at the interface and calcium phosphates in the matrix. We conclude that a bone bioreactor can be used as an alternate tool for in-vivo bone ingrowth studies of new implant surfaces or coatings.

Experimental and Numerical Study of Shear Interface Response of Hybrid Thin CFRP–Concrete Slabs

Hybrid slabs made of carbon-fiber-reinforced polymer (CFRP) and concrete provide a solution that takes advantage of the strength properties of both materials. The performance of the system strongly depends on the CFRP–concrete interaction. This study investigates the shear behavior in the interface of the two materials. Eight full-scale experiments were carried out to characterize the interface shear response of these hybrid elements using different connection solutions. An untreated surface is compared to a surface with aggregates, with a novel system comprising a flexible, straight glass fiber mesh and an inclined glass fiber mesh. The experimental results show that the fabric connection improves the friction between materials and is responsible for the pseudo-plastic performance of the specimens. The inclined mesh produces a more uniform tightening effect compared to the straight mesh. In simulations via the finite element method, we used an adjusted frictional model to reproduce the experiments.

Comparison of the Masticatory Force (with 3D Models) of Complete Denture Base Acrylic Resins with Reline and Reinforcing Materials

The reinforcement of acrylic denture base remains problematic. Acrylic prosthesis fractures are commonly observed in prosthodontic practice and have not been reliably resolved. This study compared the resistance to masticatory force of acrylic bases of removable complete conventional prosthesis in 3D upper models. Forty acrylic base test specimens containing two types of reinforcement meshes (20 with glass fiber meshes (FIBER-FORCE®- Synca, Bio Composants MédicauxTM, Tullins, France), 20 with metal meshes (DENTAURUM®-Ispringen, Germany)), 20 with a conventional PMMA acrylic base (LUCITONE 199®-Dentsply Sirona, York, PA, USA), and 20 using a permanent soft reline material (MOLLOPLAST-B®-DETAX GmbH & Co. KG, Ettlingen, Germany) were tested—a total of 80 specimens. Half of the specimens were made for a low alveolar ridge and half for a high alveolar ridge. The data were analysed using one-way analysis of variance and Student’s t-test for independent test specimens. In the high-alveolar-ridge group, the prosthesis reinforced with the glass fiber mesh was the most resistant to fracture, while in the low-alveolar-ridge group, the non-reinforced prosthesis showed the highest resistance masticatory force. Prostheses with the permanent soft reline material showed the lowest resistance to fracture in both high and low-alveolar-ridge groups. The results show that the selection of the right reinforcement material for each clinical case, based on the height of the alveolar ridge, may help to prevent prosthesis fractures.

Strength Parameters of Foamed Geopolymer Reinforced with GFRP Mesh

The foaming of geopolymers lowers their density, thus opening up new environmental benefits, including acoustic and thermal insulation. At the same time, foaming disturbs the homogeneity of the material, which worsens the strength parameters, and particularly those related to tension, which can be improved by introducing reinforcement. This paper presents the results of research on foamed geopolymers reinforced with glass fiber meshes, a type of reinforcement that provides an adequate bond. The samples tested here were based on three types of coal fly ash, and were foamed with varying doses of hydrogen peroxide. Samples were cured at 40 °C and were tested after 28 days of maturing at ambient temperature. The strength parameters of the synthesized geopolymers were determined via laboratory testing, and were used to evaluate load-bearing capacity models of the tested samples reinforced with glass fiber mesh. The results showed the importance of the type of ash on the strength properties and efficiency of reinforcement. At the same time, a slight deterioration in the glass fibers was noticed; this was caused by the presence of sodium hydroxide solution, which was used as an activator.

Masonry buildings strengthened with textile-fiber composite (TRC) layers and fiber-reinforced cementitious (FRC) layers

In June 2015, the authors published a paper titled “Brief Report of Shaking Table Test on Masonry Building Strengthened with Ferrocement Layers” [1]. The authors suggested in that paper to replace the traditional way of constructing masonry houses using the so called practical columns and beams (herein after called traditional masonry houses) with bandaging using ferrocement layers on both sides of the walls as skin facings and brick wall as core. Since then, many masonry houses bandaged with ferrocement layers are built in Indonesia. Apart from constructing new earthquake resistant houses, ferrocement bandaging is also used for retrofitting existing as well as damaged houses after earthquakes. In the past decades, continuous fiber mesh was introduced to replace the steel wire mesh in a cementitious matrix. Since the early 2000, textile-based composites were used in the field of strengthening and seismic retrofitting of masonry as well as concrete structures. Originally these new “textile fiber composite” materials are called “Textile Reinforced Concrete” (TRC) in Europe. However, in the USA, the term used is “Fiber Reinforced Cementitious Matrix systems” (FRCM). Extensive research on FRCM / TRC were conducted. A wide variety of publications on the subject matter are now available worldwide. Apart from TRC, many technical studies are published addressing fiber reinforced cement and concrete composite. The term “Fiber Reinforced Cementitious” (FRC) is used and defined as concrete and/or cementitious matrix with suitable discontinuous fibers added to it for the purposes of achieving a desired level of performance in a particular property, such as modulus elasticity, tensile strength, and ductility [2]. Lately, the use of discontinuous fibers as reinforcement for concrete and cementitious matrix FRC are introduced by many practitioners and civil engineers. Adding fibers in concrete / cementitious matrix mixer simply like adding sand or admixtures, to create a homogenous, isotropic, strong, tough, durable, and moldable structural materials [2]. In this paper the authors used the terms of TRC and FRC as defined by Naaman [2, 3], namely TRC for fiber-cement with fiber-mesh and FRC for fiber-cement with discontinuous fiber. This paper provides a simplified global analysis of the overall structure strengthened with FRCM / TRC as well as strengthened with FRC.