One significant barrier to the translation of tissue-engineered constructions is vascularization. It is still difficult for manufacturing science to directly fabricate hollow, vascular-like channels inside tissue-like gel materials. Using a robotic-arm controlled 3D printer to move user-defined needle tips through the gel materials is one suggested technique. In order to create the hollow channel inside gels and forecast the amount of insertion force and deflection, the needle gel interaction-related contact phenomenon was both simulated and empirically validated in this work. The geometric shape of the needle tip, speed variations, and gel characteristics are some of the factors that affect needle navigation. It was discovered that high needle diameters produced enormous insertion forces, and that insertion force increased as needle speed increased. Conversely, it was discovered that as the diameter and insertion velocity of the needle increased, the deflection of the needle decreased. Furthermore, a bevel-shaped needle tip displayed a greater deflection than a conical needle tip because of its non-isometric shape. The manufacturing methodology for creating hollow channels for vascularization in tissue-engineered structures and subsurface, enclosed microfluidic research is further developed as a result of this paper.

The aim of this study was to evaluate the effect of different irrigation solutions used during root canal irrigation in root canal treatment on the microhardness of nickel-titanium (NiTi) files subjected to different heat treated. The pre-preparation microhardness levels of EndoArt Smart Blue and EndoArt Smart Gold (İnci Dental Productions Co, Istanbul, Turkey) file systems were measured at five different points using a microhardness testing device (HMV-2000; Shimadzu, Tokyo, Japan). Microhardness evaluation was performed on thirty-two 30.04 files from each file system. A total of 64 single-rooted and single-canaled mandibular incisor teeth were prepared up to size 30.04 using file systems. The preparation was completed with the irrigation solutions (5.25% NaOCl, 17% EDTA, ozonated water, and distilled water) for an average of 3 min with a 30.04 file. After preparation, the microhardness levels of the 30.04 files were again measured. The differences between the microhardness values were statistically compared. According to the obtained data, the pre-preparation measurement values were higher than the post-preparation values (p < 0.05). No statistically significant differences were found between the microhardness measurement values (p > 0.05). The highest and lowest microhardness changes were observed in the EndoArt Smart Blue file system, in the ozonated water (195.63 ± 71.04 VHN (Vickers Hardness Number)) and distilled water (152.88 ± 51.10 VHN) groups, respectively. In this study, different irrigation solutions did not have a statistically significant effect on the microhardness of heat-treated NiTi files.

Given the increasing use and availability of dental implants, this study aimed to compare the primary stability of two commonly used implants with similar designs: 'type A (Cowellmedi), an imported design, and type B (DRI), a domestically manufactured implant,' in both synthetic (polyurethane foam) and natural bone (bovine rib). Both implants had a diameter of 4 mm and a length of 10 mm, with a buttress thread profile. Type B was single-threaded, while type A was double-threaded with a more conical design. In natural bone, type A demonstrated significantly higher maximum insertion torque (p = 0.033), bone-implant construct stiffness (p < 0.001), and maximum push-in force (p < 0.001) compared with type B. In contrast, in synthetic bone, type B showed significantly higher bone-implant construct stiffness (p = 0.02) and greater maximum push-in force (p < 0.001). Implant stability quotient (ISQ) values did not differ between the two designs in either bone type. The findings suggest that type A achieved greater primary stability due to its double-threaded configuration and longer conical region. Subtle design differences, such as single- versus double-threading and a longer conical region, can therefore have a considerable impact on primary stability and should not be overlooked when developing new implant designs. Finally, the discrepancies observed between stability outcomes in natural and synthetic bone are likely due to differences in their mechanical behavior. This highlights the need for caution when interpreting data derived from synthetic bone, particularly when attempting to extrapolate findings to natural bone-implant systems.

This study assesses the synthesis and characterization of titanium implant surface nanocoating with graphene oxide (GO) at varying concentrations. Nanocoatings were applied using the dip coating technique, and GO nanoparticles were synthesized chemically. Physicochemical, morphological, and biological characterizations were conducted using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, in vitro bioactivity assay, cell viability, and colony-forming units per milliliter (CFU/mL). Cell viability data were subjected to two-way ANOVA, followed by Tukey's test (α = 0.05). CFU/mL data were analyzed using the Kruskal-Wallis test, followed by Dunn's test (α = 0.05). TEM revealed a sheet-like structure of GO nanoparticles. SEM showed the roughness of the nanocoated titanium surface. Raman spectroscopy indicated the presence of GO on the titanium surface, as evidenced by D and G bands. Higher apatite crystal deposition was observed on surfaces with greater GO concentrations at 7 and 14 days (bioactivity assay). The highest percentage of cell viability was noted in the 1.5% GO group after 48 h, compared to other groups at different time points (p < 0.05). Surface treatment with varying GO concentrations induced greater cell viability compared to the acidic treatment (p < 0.05). The 1.5% GO group showed the lowest antibacterial efficacy, as evidenced by the highest CFU/mL values (p < 0.05). GO particles remained stable and chemically unchanged during the coating process. The GO-coated titanium surfaces showed no cytotoxicity and exhibited notable bioactive and antibacterial effects against Streptococcus mutans. These findings suggest that GO coatings may effectively enhance the biological and antimicrobial performance of titanium implants.

This study focuses on analyzing how various input parameters affect the output parameters of cutting time and cutting site temperature when cutting through chicken and rat femur bones and also aims to provide insights into optimizing cutting processes in these contexts. In this research, two ultrasonic surgical knives were designed and simulated using Abaqus software. The system design was then optimized and the knife parts were assembled after machining. The bone cutting process was performed on chicken femur and rat femur bones using both wet and dry cutting modes with an ultrasonic bone scalpel circuit resonance and saw and sharp-edge blades with vibration amplitudes of 18, 22.5, and 27 µm. The experiments were designed as a full factorial, and an ANN model was used to interpret and predict the cutting responses. Increasing the vibration amplitude from 18 to 27 µm reduced the cutting time by 30% for the sharp-edge blade and 33% for the saw-edge blade in dry cutting and by approximately 30%-40% in wet cutting. The cutting temperature also decreased significantly with increasing amplitude, by approximately 27% (sharp edge) and 30% (saw edge) in dry conditions and by approximately 19% in wet conditions (with two blades). Overall, the saw-edge blade showed a 52%-72% shorter cutting time and 50%-70% lower temperature compared to the sharp-edge blade in both cutting conditions. Finally, the ANN model data results showed a good agreement with the actual data for cutting temperature and time.

Dental implantation is the most reliable method for replacing missing teeth. Success rate of dental implants is influenced by osseointegration. Surface roughness of implants influences osseointegration by altering surface area and texture, providing stimulation to cells. Sandblasting and acid-etching are common methods for making implant surfaces rough. Main goal of this study was to investigate effects of sandblasting and acid-etching variables, that is, blasting-pressure and acid-temperature, on surface roughness of implants to find the controlled values of variables for a favorable surface roughness. An acceptable surface roughness was assumed to have an arithmetic average height (Sa) between 1 and 2 µm, and an area developed ratio (Sdr) over 50%. Seventy-two titanium-made analogs were sandblasted with three different pressures, that is, 4, 5, and 6 MPa, and three different durations, that is, 15, 30, and 45 s, and then were etched with two different etching temperature, that is, 60°C and 80°C, and two exposure-time, that is, 5 and 10 min (two repetition for each combination). Surface roughness parameters were then measured using a profilometer. Multi-factorial ANOVA was used as statistical analysis method. Results showed that 14 groups demonstrated favorable Sa (1-2 µm), among which just four groups had acceptable Sdr (Sdr > 50%). Among four parameters stated above, which affect sandblasting and acid-etching processes, it was found that blasting duration is the most effective variable on implants roughness. This work highlights the importance of sandblasting and acid-etching parameters for a controlled titanium dental implant surface, which can achieve surface roughness parameters that correspond to those previously reported in the literature as favorable ones for osseointegration.

In recent years, hierarchical porous structures have garnered extensive attention across multiple disciplines, inspired by their natural counterparts. While structural hierarchy significantly affects overall performance, the mechanistic influence of multiple hierarchical parameters on scaffold mechanical properties remains insufficiently systematized. In this study, a series of hierarchical porous scaffolds (with macro-to-micro pore size ratios of at least 10) featuring different hierarchical parameters were designed and fabricated. The presence of hierarchical structures and the effects of varying hierarchical spacing and pore size parameters on macroscopic structural performance were analyzed through experimental and computational methods. Results indicate that the introduction of hierarchical structures has a significant impact on the mechanical properties of scaffolds. As hierarchical pore size increases or spacing decreases, the mechanical properties of the structure exhibit a decreasing trend, and the maximum reduction in the compressive modulus reaches 25.82% and 45.62%, respectively. Moreover, a coupling mechanism exists between pore size and spacing, and the trend of simulation and experimental results aligns. These findings demonstrate that synergistic tuning of hierarchical parameters enables effective control over scaffold mechanical behavior. This offers new insights and lays a solid theoretical and experimental foundation for developing ideal bone scaffolds with tunable mechanical properties.

Bone machining is a critical aspect of orthopedic surgeries, where excessive heat generation can cause thermal necrosis and hinder patient recovery. Ultrasonic-assisted micro-milling (UAM) offers advantages by reducing cutting forces and heat generation. This study examines the effects of feed rate, rotational speed, tool diameter, depth of cut, and vibration amplitude on cutting force and temperature in UAM of cortical bone. 64 experiments were performed on fresh bovine cortical bone specimens prepared to consistent dimensions and stored to prevent moisture loss. Repeated central points in the design quantified experimental error and repeatability. Precision, calibrated instruments ensured accurate force and temperature measurements. Data were analyzed using regression modeling and statistical methods. Results showed that increasing rotational speed and vibration amplitude generally reduced cutting force and temperature, while feed rate and tool diameter had complex interactive effects. Multi-objective optimization using NSGA-II identified optimal conditions: for the X-axis, 1047 rpm, 63 mm/min feed, 1.5 mm diameter, 0.6 mm depth, and 30 μm amplitude; for the Y-axis, 990 rpm, 22 mm/min, 0.8 mm diameter, 0.2 mm depth, and 20 μm amplitude. Predictive models achieved temperature errors of 1.6% (X) and 7.6% (Y), and force errors of 12.9% (X) and 14.5% (Y). These models can help surgeons anticipate cutting conditions preoperatively, reducing surgical risks and preserving bone integrity. The findings support optimization of orthopedic machining processes, improving surgical outcomes and advancing bone-milling techniques.

Various strategies have been proposed to reduce operator-dependent variability in musculoskeletal ultrasound, including mechanical stabilization techniques. However, their effects on image reproducibility and transducer handling remain unclear in anatomically complex regions such as hand. This two-phase study aimed to (1) develop and validate a transducer guiding system for hand ultrasound and (2) evaluate its influence on image reproducibility and operational stability through image-based analyses. In Phase I, test-retest reliability of the guiding system was examined by repeatedly measuring soft-tissue thickness in 30 healthy participants. Intraclass Correlation Coefficients (ICC) ranged from 0.766 to 0.948, demonstrating good to excellent reliability. In Phase II, 16 ultrasound users acquired images under handheld and guiding-system-assisted conditions based on predefined reference images. Image reproducibility was evaluated using Normalized Cross-Correlation (NCC) and ICC, while operational stability was assessed via cosine similarity derived from M-mode segments during the pre-capture period, with group comparisons performed using the Wilcoxon signed-rank test. Novice users showed substantial ICC improvement when using the guiding system (0.487-0.681), approaching the consistency observed in experienced users. Both novice and experienced groups displayed higher NCC and cosine similarity values with the guiding system, indicating improved reproducibility and operational stability. Overall, the guiding system enhanced image outcomes by providing standardized positioning and mechanical stabilization. These findings highlight its potential to improve consistency in hand ultrasound assessments and serve as a supportive tool for novice ultrasound training. The results further demonstrate the feasibility of mechanical stabilization in reducing operator-related variability and enhancing image consistency in hand ultrasound examinations.

The aim of this study is to investigate the mechanical influence on the aortic tissue when exposed to the liquid jet blasting effect produced by the aortic cannula during cardiothoracic surgery. Aortic tissue from seven porcine hearts was exposed to a continuous liquid jet from an aortic cannula positioned in a simple flow loop. After 4 h of exposure, samples were obtained from the aortic root using a twin punch device. Additionally, tissue was harvested from seven untouched aortic roots serving as our control group. Uniaxial tensile testing was conducted to measure the ultimate strength and Young's modulus. Furthermore, we analysed the samples using dynamic mechanical analysis in the frequency range from 0.5 to 5 Hz. There were no significant differences in ultimate tensile strength or Young's modulus between the test group and control group. Dynamic mechanical analysis revealed significant increases in both mean storage modulus (44%) and mean loss modulus (73%) in the exposed samples. There was a tendency towards higher tanδ in the test group, suggesting altered viscoelastic behaviour. These findings indicates that the liquid jet exposure influences the viscoelastic properties of the aortic wall and makes it stiffer. Further studies should incorporate histological and microstructural analyses to confirm mechanical alterations at the tissue level. Clinically, such changes may contribute to local wall injury, altered flow dynamics, or plaque destabilisation during cardiopulmonary bypass. This highlighting the need for optimisation of cannula flow direction and velocity to minimise the mechanical impact on the aortic wall.