The induction of bone formation by 3D-printed PLGA microsphere scaffolds in a calvarial orthotopic mouse model: a pilot study.

Polymeric biodegradable microspheres are readily utilized to support targeted drug delivery for various diseases clinically. 3D printed tissue engineering scaffolds from polymer filaments with embedded microspheres or nanoparticles, as well as bulk microsphere scaffolds, have been investigated for regenerative medicine and tissue engineering. However, 3D printed scaffolds consisting only of a homogenous microsphere size with an optimized architecture that includes a unique micro- and macroporosity, have been challenging to produce and hence, have not been assessed in the literature yet.

Effect of Model Body Type and Print Angle on the Accuracy of 3D-Printed Orthodontic Models.

The assortment of low-cost 3D printers for "in-practice" use, e.g., for clear aligner therapies, is ever increasing.

The 3D-McMap Guidelines: Three-Dimensional Multicomposite Microsphere Adaptive Printing.

Microspheres, synthesized from diverse natural or synthetic polymers, are readily utilized in biomedical tissue engineering to improve the healing of various tissues. Their ability to encapsulate growth factors, therapeutics, and natural biomolecules, which can aid tissue regeneration, makes microspheres invaluable for future clinical therapies. While microsphere-supplemented scaffolds have been investigated, a pure microsphere scaffold with an optimized architecture has been challenging to create via 3D printing methods due to issues that prevent consistent deposition of microsphere-based materials and their ability to maintain the shape of the 3D-printed structure.

Implant system for large osteochondral defects.

Issues with current treatments for osteochondral defects such as mosaicplasty and autologous chondrocyte implantation (ACI) are lack of donor material, problems associated with donor sites, necessity of second surgical intervention and cell expansion, difficult site preparation and implant fitting to match the surrounding tissue. This study presents the development of a patient specific implant system for focal osteochondral defects that addresses these issues. Using computer aided design and manufacturing techniques, computed tomography scans are utilized to design the implant and templates that facilitate site preparation to allow for precise and easy implantation of the designed perfectly fitting tissue replacement.

Effect of fluoride varnish in combination with simulated oral environment on enamel-bracket shear bond strength.

To determine the effect of fluoride varnish application combined with a simulated oral environment prior to bracket bonding on the shear bond strength (SBS) between brackets and tooth enamel. Sixty de-identified, extracted teeth were grouped to either receive or not receive fluoride varnish and then stored for 7 days at 37 °C in phosphate-buffered saline (PBS) solution or PBS combined with three 15-min cycles/day in a demineralizing solution to simulate pH variation following meals. Subsequently, brackets were bonded and after 24-h dark cure at 37 °C, debonded using shear forces in a simulated oral environment.

Polymer-coated microparticle scaffolds engineered for potential use in musculoskeletal tissue regeneration.

Biomaterials constructed exclusively of sintered microspheres have great potential in tissue engineering scaffold applications, offering the ability to create shape-specific scaffolds with precise controlled release yet to be matched by traditional additive manufacturing methods. The problem is that these microsphere-based scaffolds are limited in their stiffness for applications such as bone regeneration. Our vision to solve this problem was borne from a hierarchical structure perspective, focusing on the individual unit of the structure: the microsphere itself.

Fabrication of a Double-Cross-Linked Interpenetrating Polymeric Network (IPN) Hydrogel Surface Modified with Polydopamine to Modulate the Osteogenic Differentiation of Adipose-Derived Stem Cells.

Hydrogel surface properties can be modified to form bioactive interfaces to modulate the osteogenic differentiation of stem cells. In this work, a hydrogel made of gelatin methacrylamide (GelMA) and alginate was designed and tested as a scaffold to control stem-cell osteogenic differentiation. The hydrogel's surface was treated with polydopamine (pDA) to create an adhesive layer for the adsorption of the osteoinductive drug dexamethasone (Dex).

Evaluating the effect of increasing ceramic content on the mechanical properties, material microstructure and degradation of selective laser sintered polycaprolactone/β-tricalcium phosphate materials.

Orthopaedic scaffold materials were fabricated from polycaprolactone (PCL) and composite PCL-β-tricalcium phosphate (PCL/β-TCP) powders using selective laser sintering (SLS). Incorporating β-TCP particles is desirable to promote osteogenesis. The effects of increasing β-TCP content on the material's mechanical properties and microstructure were evaluated.

Computational modelling of ovine critical-sized tibial defects with implanted scaffolds and prediction of the safety of fixator removal.

Computational model geometries of tibial defects with two types of implanted tissue engineering scaffolds, β-tricalcium phosphate (β-TCP) and poly-ε-caprolactone (PCL)/β-TCP, are constructed from µ-CT scan images of the real in vivo defects. Simulations of each defect under four-point bending and under simulated in vivo axial compressive loading are performed. The mechanical stability of each defect is analysed using stress distribution analysis.

Improving the finite element model accuracy of tissue engineering scaffolds produced by selective laser sintering.

In bone tissue engineering, both geometrical and mechanical properties of a scaffold play a major part in the success of the treatment. The mechanical stresses and strains that act on cells on a scaffold in a physiological environment are a determining factor on the subsequent tissue formation. Computational models are often used to simulate the effect of changes of internal architectures and external loads applied to the scaffold in order to optimise the scaffold geometry for the prospective implantation site.

Evaluation of a Multiscale Modelling Methodology to Predict the Mechanical Properties of PCL/β-TCP Sintered Scaffold Materials.

A multiscale modelling methodology to predict the macroscale stiffness of selective laser sintered polycaprolactone (PCL)/β-tricalcium phosphate (β-TCP) materials is evaluated. The relationship between a micromechanics-evaluated composite material elastic modulus (E eff) and segment grey-value (GVave) is established for a 90/10 wt% PCL/β-TCP material and compared to the previously established E eff vs. GVave relationship for a 50/50 wt% PCL/β-TCP material.

Predicting the elastic properties of selective laser sintered PCL/β-TCP bone scaffold materials using computational modelling.

This study assesses the ability of finite element (FE) models to capture the mechanical behaviour of sintered orthopaedic scaffold materials. Individual scaffold struts were fabricated from a 50:50 wt% poly-ε-caprolactone (PCL)/β-tricalcium phosphate (β-TCP) blend, using selective laser sintering. The tensile elastic modulus of single struts was determined experimentally.

Laser sintering for the fabrication of tissue engineering scaffolds.

Laser sintering (LS) utilises a laser to sinter powder particles. A volumetric model is sliced and processed cross section by cross section to create a physical part. In theory, all powdered materials are suitable for sintering; however, only few have been tested successfully.

Fabrication, mechanical and in vivo performance of polycaprolactone/tricalcium phosphate composite scaffolds.

This paper explores the use of selective laser sintering (SLS) for the generation of bone tissue engineering scaffolds from polycaprolactone (PCL) and PCL/tricalcium phosphate (TCP). Different scaffold designs are generated, and assessed from the point of view of manufacturability, porosity and mechanical performance. Large scaffold specimens are produced, with a preferred design, and are assessed through an in vivo study of the critical size bone defect in sheep tibia with subsequent microscopic, histological and mechanical evaluation.

Investigation of the mechanical interaction of the trabecular core with an external shell using rapid prototype and finite element models.

The mechanical properties of vertebral bone have been widely studied with the ultimate goal of improving fracture risk prediction. However, the mechanical interaction between the cortical shell and the trabecular core is not well understood. The objective of this study was to investigate this interaction and to determine what effect it has on the ultimate strength of the whole bone.

Selective laser sintering of hydroxyapatite/poly-epsilon-caprolactone scaffolds.

Selective laser sintering (SLS) enables the fabrication of complex geometries with the intricate and controllable internal architecture required in the field of tissue engineering. In this study hydroxyapatite and poly-epsilon-caprolactone, considered suitable for hard tissue engineering purposes, were used in a weight ratio of 30:70. The quality of the fabricated parts is influenced by various process parameters.

Finite element predictions compared to experimental results for the effective modulus of bone tissue engineering scaffolds fabricated by selective laser sintering.

A current challenge in bone tissue engineering is to create scaffolds with suitable mechanical properties, high porosity, full interconnectivity and suitable pore size. In this paper, polyamide and polycaprolactone scaffolds were fabricated using a solid free form technique known as selective laser sintering. These scaffolds had fully interconnected pores, minimized strut thickness, and a porosity of approximately 55%.

Biomodels of bone: a review.

In this paper, a definition of a biomodel is presented, based on which different specific types of biomodels are identified, viz., virtual biomodels, computational biomodels, and physical biomodels. The paper then focuses on both physical and virtual biomodels of bone, and presents a review of model generation methodologies, giving examples of typical biomodel applications.