ABSTRACT
The joining zone includes three main parts, which comprise an isothermal solidification zone (ISZ), the athermal solidification zone (ASZ), and a diffusion affected zone (DAZ). Field emission scanning electron microscopy (FESEM) was used here to observe the microstructure equipped with ultra-thin window energy dispersive X-ray spectrometer (EDS) system. Additionally, electrochemical impedance spectroscopy (EIS) and cyclic potentiodynamic polarization tests were conducted to evaluate the effect of the DB process on the corrosion resistance of the Inconel 625 superalloy. In the bonding time period, some Mo- and Cr-rich boride precipitations and Ni-rich γ-solid solution phases with hardened alloy elements, such as Mo and Cr, formed in DAZ and ASZ, respectively, because of the inter-diffusion of melting point depressants (MPD). Moreover, during cooling cycles, Ni-Cr-B, Ni-Mo-B, Ni-Si-B, and Ni-Si phase compounds were formed in the ASZ area at 1110-850 °C. The DAZ area developed by borides compound with cubic, needle, and grain boundary morphologies. The corrosion tests indicated that the DB process led to a reduction in the passive region and increased the sensitivity to pitting corrosion.
ABSTRACT
Three-dimensional (3D) bioprinting technology has emerged as an ideal approach to address the challenges in regenerative dentistry by fabricating 3D tissue constructs with customized complex architecture. The dilemma with current dental treatments has led to the exploration of this technology in restoring and maintaining the function of teeth. This scoping review aims to explore 3D bioprinting technology together with the type of biomaterials and cells used for dental applications. Based on PRISMA-ScR guidelines, this systematic search was conducted by using the following databases: Ovid, PubMed, EBSCOhost and Web of Science. The inclusion criteria were (i) cell-laden 3D-bioprinted construct; (ii) intervention to regenerate dental tissue using bioink, which incorporates living cells or in combination with biomaterial; and (iii) 3D bioprinting for dental applications. A total of 31 studies were included in this review. The main 3D bioprinting technique was extrusion-based approach. Novel bioinks in use consist of different types of natural and synthetic polymers, decellularized extracellular matrix and spheroids with encapsulated mesenchymal stem cells, and have shown promising results for periodontal ligament, dentin, dental pulp and bone regeneration application. However, 3D bioprinting in dental applications, regrettably, is not yet close to being a clinical reality. Therefore, further research in fabricating ideal bioinks with implantation into larger animal models in the oral environment is very much needed for clinical translation.
ABSTRACT
Three-dimensional-printed scaffolds have received greater attention as an attractive option compared to the conventional bone grafts for regeneration of alveolar bone defects. Hydroxyapatite and tricalcium phosphates have been used as biomaterials in the fabrication of 3D-printed scaffolds. This scoping review aimed to evaluate the potential of 3D-printed HA and calcium phosphates-based scaffolds on alveolar bone regeneration in animal models. The systematic search was conducted across four electronic databases: Ovid, Web of Science, PubMed and EBSCOHOST, based on PRISMA-ScR guidelines until November 2021. The inclusion criteria were: (i) animal models undergoing alveolar bone regenerative surgery, (ii) the intervention to regenerate or augment bone using 3D-printed hydroxyapatite or other calcium phosphate scaffolds and (iii) histological and microcomputed tomographic analyses of new bone formation and biological properties of 3D-printed hydroxyapatite or calcium phosphates. A total of ten studies were included in the review. All the studies showed promising results on new bone formation without any inflammatory reactions, regardless of the animal species. In conclusion, hydroxyapatite and tricalcium phosphates are feasible materials for 3D-printed scaffolds for alveolar bone regeneration and demonstrated bone regenerative potential in the oral cavity. However, further research is warranted to determine the scaffold material which mimics the gold standard of care for bone regeneration in the load-bearing areas, including the masticatory load of the oral cavity.
ABSTRACT
BACKGROUND: Diabetic foot ulcer is commonly seen in people with diabetes mellitus. Inadequate plantar pressure offloading has been identified as a contributing factor to development of diabetic foot ulcers. Various pressure off-loading footwear are widely available in the market but poor compliance has been reported especially for indoor usage. StepEase™ diabetic socks have been designed using Ethylene Vinyl Acetate (EVA) microspheres for better redistribution of plantar pressure. The objective of this study was to determine the efficacy of StepEase™ in redistributing the foot plantar pressure and to assess patients' satisfaction on the usage of the socks. METHODS: This was a prospective non randomized clinical trial conducted on 31 patients with diabetes mellitus with high risk foot (King's classification stage II) over a 12 weeks period. Dynamic foot plantar pressure reading was recorded at day 0, 6 weeks and 12 weeks intervals, both barefoot and with StepEase™, using Novel Pedar-X system (Novel GmbH, Munich, Germany). Patients' satisfaction and usage practice were assessed by a questionnaire. RESULTS: The mean age of subjects was 57.9 years with mean body mass index (BMI) of 26 kg/m2. The mean duration of diagnosis with diabetes mellitus was 10.2 years. The mean peak plantar pressure was found to be highest at the right forefoot and left heel region, 267.6 kPa (SD113.5 kPa) and 266.3 kPa (SD 94.6 kPa) respectively. There was a statistically significant reduction of mean peak pressure (P < 0.0001 to P = 0.024) in all masked regions except the left toe region ranging from 22.3 to 47.5% (53.2-117.4 kPa). The highest reduction was seen in the right toe region (47.5%). The reduction of peak pressure was still significant (P < 0.0001 to P = 0.034) at 6 weeks ranging from 24.7% to 46.8% (46.1-100.6 kPa) and at 12 weeks, which was 22.2-49.2% (40.6-91.9 kPa). Mean usage of the socks was 4.39 days per week (SD 1.82), with the mode of 4-6 h per day. Most of the subjects were satisfied or very satisfied with the StepEase™ socks (77.4%) while 87.1% agreed to continue using the socks. None had any new ulcer development or fall during the study period. CONCLUSION: StepEase™ was significantly effective as an indoor foot pressure relieving footwear. It resulted in significant peak plantar pressure reduction by up to 49.2% and the effect was maintained for at least 12 weeks duration.
Subject(s)
Diabetic Foot/prevention & control , Diabetic Foot/therapy , Adult , Female , Foot/physiopathology , Germany , Humans , Male , Middle Aged , Pressure/adverse effects , Prospective StudiesABSTRACT
In this study, Ag2O was synthesized on polyethylene terephthalate fabrics by using an ultrasonic technique with Ag ion reduction in an aqueous solution. The effects of pH on the microstructure and antibacterial properties of the fabrics were evaluated. X-ray diffraction confirmed the presence of Ag2O on the fabrics. The fabrics were characterized by Fourier transform infrared spectroscopy, ultravioletâ»visible spectroscopy, and wettability testing. Field-emission scanning electron microscopy verified that the change of pH altered the microstructure of the materials. Moreover, the antibacterial activity of the fabrics against Escherichia coli was related to the morphology of Ag2O particles. Thus, the surface structure of Ag2O particles may be a key factor of the antibacterial activity.
