A large variety of approaches have been used to treat large and irregular shaped bone defects with less than optimal success due to material or design issues. In recent years patient specific constructs prepared by additive manufacturing provided a solution to the need for shaping implants to fit irregular defects in the surgery theater. In this study, cylindrical disks of poly(ε-caprolactone) (PCL) were printed by fused deposition modeling and modified with nanohydroxyapatite (HAp) and poly(propylene fumarate) (PPF) to create a mechanically strong implant with well-defined pore size and porosity, controllable surface hydrophilicity (with PPF) and osteoconductivity (with HAp). Cytotoxicity, irritation and inflammation tests demonstrated that the scaffolds were biocompatible. PCL/HAp and PCL/HAp/PPF scaffolds were implanted in the femurs of rabbits with and without seeding with rabbit Bone Marrow Stem Cells (BMSC) and examined after 4 and 8 weeks with micro-CT, mechanically and histologically. BMSC seeded PCL/HAp/PPF scaffolds showed improved tissue regeneration as determined by bone mineral density and micro-CT. Compressive and tension stiffness values (394 and 463 N mm⁻¹) were significantly higher than those of the healthy rabbit femur (316 and 392 N mm⁻¹, respectively) after 8 weeks of implantation. These 3D implants have great potential for patient-specific bone defect treatments.

Objectives:To investigate voids in different root canal sealers using micro-CT and nano-CT, and to explore the feasibility of using nano-CT for quantitative analysis of sealer filling quality.Methods:30 extracted mandibular central incisors were randomly assigned into three groups according to the applied root canal sealers (Total BC Sealer, Sure Seal Root, AH Plus) by the single cone technique. Subsequently, micro-CT and nano-CT were performed to analyse the incidence rate of voids, void fraction, void volume and their distribution in each sample.Results:Micro-CT evaluation showed no significant difference among sealers for the incidence rate of voids or void fraction in the whole filling materials (p > 0.05), whereas a significant difference was found between AH Plus and the other two sealers using nano-CT (p < 0.05). All three sealers presented less void volume in the apical third; however, higher void volumes were observed in the apical and coronal thirds in AH Plus using micro-CT (p < 0.05), while na...

While several materials and techniques have been used to assess the quality of root canal fillings in micro-CT images, the lack of standardization in scanning protocols has produced conflicting results. Hence, the aim of this study was to determine a cutoff voxel size value for the assessment of root canal filling voids in micro-CT and nano-CT images. Twenty freshly extracted mandibular central incisors were used. Root canals were prepared with nickel titanium files to an ISO size 40/0.06 taper and then filled with a single cone (40/0.06 taper) and AH Plus sealer. The teeth were scanned with different voxel sizes with either micro-CT (5.2, 8.1, 11.2, and 16.73 μm) or nano-CT (1.5 and 5.0 μm) equipment. Images were reconstructed and analyzed with the NRecon and CTAn software. Void proportion and void volume were calculated for each tooth in the apical, middle, and coronal thirds of the root canal. Kruskal-Wallis and post hoc Mann–Whitney U tests were performed with a significance level of 5%. In micro-CT images, significantly different results were detected among the tested voxel sizes for void proportion and void volume, whereas no such differences were found in nano-CT images (p>0.05). Micro-CT images showed higher void numbers over the entire root length, with statistically significant differences between the voxel size of 16.73 μm and the other sizes (p<0.05). The values of the different nano-CT voxel sizes did not significantly differ from those of the micro-CT (5.2, 8.1, and 11.2 μm), except for the voxel size of 16.73 μm (p<0.05). All tested voxel sizes enabled the detection of root canal filling voids except for the voxel size of 16.73 μm. Bearing in mind the limitations of this study, it seems that a voxel size of 11.2 μm can be used as a reliable cutoff value for the assessment of root canal filling voids in micro-CT imaging.

The aim of this study was to target nano sized (266 ± 25 nm diameter) poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) particles carrying Doxorubicin (DOX), an anticancer agent, to human osteosarcoma cells (Saos-2). A nuclear targeting molecule (Nuclear Localization Signal, NLS), a 17 a.a. peptide, was attached onto the doxorubicin loaded nanoparticles. NLS conjugated nanoparticles surrounded the cell nuclei, but did not penetrate them. Free doxorubicin and doxorubicin loaded nanoparticles entered the cytoplasm and were evenly distributed within the cytoplasm. The localization of the NLS-targeted particles around the nuclear membrane caused a significantly higher decrease in the cancer cell numbers due to apoptosis or necrosis than the untargeted and free doxorubicin formulations showing the importance of targeting the nanoparticles to the nuclear membrane in the treatment of cancer.

A novel three-dimensional construct was designed to serve as a substitute for the natural meniscus tissue, and tested in vitro. The design consisted of mats of aligned collagen micro/nanofibers, entrapped within a macroporous poly(l-lactic acid)/poly(lactic acid-co-glycolic acid) foam coated with Ca⁺²-cross-linked alginic acid. Fibrochondrocytes derived from human meniscus were tested in vitro to study cell attachment and proliferation. After a 21-day culture, the cells populating the constructs were shown to produce extracellular matrix components specific for fibrocartilages, such as collagen Types I and II and aggrecan. Coating the foam with alginate increased the compressive modulus of the collagen-containing constructs (from 320 to 381 kPa, after 21 days of incubation with fibrochondrocytes) but decreased cell attachment and proliferation, as well as aggrecan production. Collagen fibers substantially increased the tensile modulus of the cell-seeded constructs (from 0.98 to 1.71 MPa for uncoated and from 0.67 to 1.32 MPa for coated samples). All constructs produced extracellular matrix components specific for fibrocartilages. These findings indicate that these constructs have potential for use as meniscus substitutes.