In Vitro Study of Surface Alterations to Polyetheretherketone and Titanium and their Effect Upon Human Gingival Fibroblasts

Statement of problem Soft-tissue attachment to different surfaces may play a pivotal role in the long-term success of dental implants. However, studies on the issue, especially on newer materials, are sparse. Purpose The purpose of this in vitro study was to evaluate the viability and adhesion of human gingival fibroblasts (HGFs) on different implant abutment materials with specific surface modifications. Material and methods One hundred and fifty specimens in 6 experimental groups were evaluated: smooth-machined titanium alloy (Ti), laser-modified titanium (TiL), smooth-machined polyetheretherketone (PEEK) (P), laser-modified PEEK (PL), plasma-treated PEEK (PP), laser- and plasma-treated PEEK (PLP). Machined Ti was considered as the control group. Surface roughness (Sa), water contact angle (WCA), and X-ray photoelectron spectroscopy (XPS) were measured. HGF attachment and proliferation were observed at 1, 3, and 7 days after cell seeding. Comparison of the means among the groups was performed with 1-way analysis of variance (ANOVA) with post hoc comparison using the Tukey test (α=.05). Results Sa values of the laser modified groups were significantly higher than those of the nonmodified (smooth-machined) groups (P\u3c.001). WCAs were significantly different among PEEK groups, and plasma-sprayed groups had the lowest WCAs. XPS analysis of both Ti and PEEK groups showed laser treatment did not have any significant effect on the surface composition of the PEEK as the same bonds with similar ratio/fraction were detected in the spectrum of the modified specimens. Scanning electron microscopy (SEM) revealed more functionally oriented HGF cells on the laser-grooved surfaces. On the first, third, and seventh day of proliferation, the titanium groups showed no significant differences (P\u3e.05). On the first and third days of proliferation, the plasma sprayed groups (PP, PLP) showed significantly greater proliferation than all experimental groups (P\u3c.001). On the seventh day of proliferation, statistically significant differences were observed between all PEEK groups and between all PEEK groups and the Ti group (P\u3c.001), with the exception of the PL and P groups and the PLP and Ti groups (P\u3e.05). Conclusions Laser-modified titanium and PEEK surfaces led to guided gingival fibroblast attachment. Plasma treatment of PEEK surfaces increased the wettability of this polymer and improved proliferation of HGF

Development of Chitosan/Gelatin/Keratin Composite Containing Hydrocortisone Sodium Succinate as a Buccal Mucoadhesive Patch to Treat Desquamative Gingivitis

The aim of this research was to develop chitosan/gelatin/keratin composite containing hydrocortisone sodium succinate as a buccal mucoadhesive patch to treat desquamative gingivitis, which was fabricated through an environmental friendly process. Mucoadhesive films increase the advantage of higher efficiency and drug localization in the affected region. In this research, mucoadhesive films, for the release of hydrocortisone sodium succinate, were prepared using different ratios of chitosan, gelatin and keratin. In the first step, chitosan and gelatin proportions were optimized after evaluating the mechanical properties, swelling capacity, water uptake, stability, and biodegradation of the films. Then, keratin was added at different percentages to the optimum composite of chitosan and gelatin together with the drug. The results of surface pH showed that none of the samples were harmful to the buccal cavity. FTIR analysis confirmed the influence of keratin on the structure of the composite. The presence of a higher amount of keratin in the composite films resulted in high mechanical, mucoadhesive properties and stability, low water uptake and biodegradation in phosphate buffer saline (pH = 7.4) containing 104 U/ml lysozyme. The release profile of the films ascertained that keratin is a rate controller in the release of the hydrocortisone sodium succinate. Finally, chitosan/gelatin/keratin composite containing hydrocortisone sodium succinate can be employed in dental applications

Mathematical Modeling of Oxygen Transfer in Porous Scaffolds for Stem Cell Growth: The Effects of Porosity, Cell Type, Scaffold Architecture and Cell Distribution

Oxygen plays a key role in human mesenchymal stem cell growth. Without adequate oxygen (hypoxic condition), cells are not able to survive, proliferate, and migrate. The objective of the present study is to investigate oxygen transfer through the cell-seeded scaffolds stored in static or dynamic bioreactors using a mathematical model. The effects of porosity, cell type, scaffold architecture and cell distribution as potential effective parameters on oxygen transfer kinetics were examined. The results suggest the substantial effect of porosity and cell type on the oxygen concentration within the scaffold compared to scaffold architecture (homogeneous vs. gradient). The obtained data show that the direction of oxygen transfer in deep regions with dead cells changes over time and reverse mass transfer allows the cells to nourish from both top and bottom layers. Finally, the extent of oxygen transfer in static bioreactors/cultures was compared to dynamic ones. The results show that dynamic bioreactors have a better performance and are more efficient for oxygen transfer

The Efficacy of Commercial Tooth Storage Media for Maintaining the Viability of Human Periodontal Ligament Fibroblasts

Aim To evaluate Save‐A‐Tooth (SAT), EMT Toothsaver (EMT) and Hank\u27s Balanced Salt Solution (HBSS) for their influence on the viability and proliferative capacity of human periodontal ligament fibroblasts (HPDLFs). Methodology Primary HPDLFs were seeded into 96‐well cell culture plates and exposed to SAT, EMT, HBSS and water (negative control) for 0.5, 1, 3, 6, 12 and 24 h at room temperature (22 °C). After each exposure time, cell viability was measured through quantifying adenosine triphosphate (ATP) using a luminescent dye. The proliferative capacity was also quantified using the PrestoBlue assay after 12 or 24 h storage in each medium. The data were analysed statistically by two‐way anova and post hoc Least Significant Difference (LSD) test (P \u3c 0.05). The morphology of the cells after 12 h storage was also investigated through live/dead viability/cytotoxicity kit together with fluorescence microscopy. Results There was no significant difference in cell viability amongst HBSS, SAT and EMT groups up to 6 h. SAT was effective in maintaining cell viability only up to 12 h and then became detrimental to HPDLF; after 24 h, the effectiveness of SAT in maintaining cell viability was similar to that of water (P \u3e 0.05). Amongst all the media, only EMT could maintain the proliferative capacity of HPDLFs significantly higher than the negative control, that is water (P \u3c 0.05) after 24 h storage. Conclusion EMT maintained the proliferative capacity of HPDLFs after 24 h storage

Development of a DNA-Liposome Complex for Gene Delivery Applications

The association structures formed by cationic liposomes and DNA(Deoxyribonucleic acid)-liposome have been effectively utilized as gene carriers in transfection assays. In this research study, cationic liposomes were prepared using a modified lipid film hydration method consisting of a lyophilization step for gene delivery applications. The obtained results demonstrated that the mean particle size had no significant change while the polydispersity (PDI) increased after lyophilization. The mean particle size slightly reduced after lyophilization (520 ± 12 nm to 464 ± 25 nm) while the PDI increased after lyophilization (0.094 ± 0.017 to 0.220 ± 0.004). In addition. The mean particle size of vesicles increases when DNA is incorporated to the liposomes (673 ± 27 nm). According to the Scanning Electron Microscopy(SEM) and transmission electron microscopy (TEM) images, the spherical shape of liposomes confirmed their successful preservation and reconstitution from the powder. It was found that liposomal formulation has enhanced transfection considerably compared to the naked DNA as negative control. Finally, liposomal formulation in this research had a better function than Lipofectamine® 2000 as a commercialized product because the cellular activity (cellular protein) was higher in the prepared lipoplex than Lipofectamine® 2000

Collagenous Matrix Supported by A 3D-Printed Scaffold for Osteogenic Differentiation of Dental Pulp Cells

Objective A systematic characterization of hybrid scaffolds, fabricated based on combinatorial additive manufacturing technique and freeze-drying method, is presented as a new platform for osteoblastic differentiation of dental pulp cells (DPCs). Methods The scaffolds were consisted of a collagenous matrix embedded in a 3D-printed beta-tricalcium phosphate (β-TCP) as the mineral phase. The developed construct design was intended to achieve mechanical robustness owing to 3D-printed β-TCP scaffold, and biologically active 3D cell culture matrix pertaining to the Collagen extracellular matrix. The β-TCP precursor formulations were investigated for their flow-ability at various temperatures, which optimized for fabrication of 3D printed scaffolds with interconnected porosity. The hybrid constructs were characterized by 3D laser scanning microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and compressive strength testing. Results The in vitro characterization of scaffolds revealed that the hybrid β-TCP/Collagen constructs offer superior DPCs proliferation and alkaline phosphatase (ALP) activity compared to the 3D-printed β-TCP scaffold over three weeks. Moreover, it was found that the incorporation of TCP into the Collagen matrix improves the ALP activity. Significance The presented results converge to suggest the developed 3D-printed β-TCP/Collagen hybrid constructs as a new platform for osteoblastic differentiation of DPCs for craniomaxillofacial bone regeneration

Synthesis And Characterization Of 3D-Printed Functionally Graded Porous Titanium Alloy

This study aims to 3D print titanium alloy constructs incorporating gradient of porosities, from the fully dense core to the porous outer surface. Gradient porous specimens were prepared using selective laser melting (SLM). Fully dense specimens fabricated by SLM were used as the control group. Characterization of samples was done using X-ray tomography, uniaxial compression testing, and optical and scanning electron microscopes. The biocompatibility of fabricated samples was investigated using human periodontal ligament stem cells via assessment of cell attachment, viability, and proliferation by direct and indirect assays. The data were analyzed using ANOVA and Tukey’s post hoc test. Characterization of constructs reveals interconnected gradient porosities and higher contact angle in porous samples. The introduction of porosity leads to a significant decrease in compression strength. However, Young’s modulus of the samples with gradient porosity was more similar to the natural bone modulus. The surface microstructure consists of loosely bonded spherical particles. Biocompatibility of the dense and porous samples is appropriate. Although the porosity size led to a reduced cell proliferation rate in the gradient sample, the extract of the gradient sample results in more cell proliferation than the dense sample’s extract. The study demonstrates that a biocompatible functionally graded porous titanium structure can be well fabricated by SLM, and this structure leads to a good match of Young’s modulus to that of the bone

From Solvent-Free Microspheres to Bioactive Gradient Scaffolds

A solvent-free microsphere sintering technique was developed to fabricate scaffolds with pore size gradient for tissue engineering applications. Poly(D,L-Lactide) microspheres were fabricated through an emulsification method where TiO2 nanoparticles were employed both as particulate emulsifier in the preparation procedure and as surface modification agent to improve bioactivity of the scaffolds. A fine-tunable pore size gradient was achieved with a pore volume of 30±2.6%. SEM, EDX, XRD and FTIR analyses all confirmed the formation of bone-like apatite at the 14th day of immersion in Simulated Body Fluid (SBF) implying the ability of our scaffolds to bond to living bone tissue. In vitro examination of the scaffolds showed progressive activity of the osteoblasts on the scaffold with evidence of increase in its mineral content. The bioactive scaffold developed in this study has the potential to be used as a suitable biomaterial for bone tissue engineering and hard tissue regeneration

Challenges in Three-Dimensional Printing of Bone Substitutes

Hope is that tissue engineering will provide a solution to meet the growing needs for bone substitutes. Among the potential solutions, three-dimensional (3D) printing is a promising method to fabricate functional bone substitutes especially for treatment of complex and critical-sized bone defects. Despite its encouraging achievements, 3D printing of bone substitutes still faces serious challenges including mechanical strength, shape complexity, optimization of pore parameters, and vascularization. The newer approach, that is, 3D bioprinting, is also confronted with challenges, which have prevented the realization of the dream of fabricating functional patient-specific bone substitutes. This article reviews the major challenges toward 3D printing and bioprinting of bone substitutes and recent studies addressing them. Potential solutions for each challenge and future directions are also provided