Applying machine learning to assess the morphology of sculpted teeth.

Background/purpose: Producing tooth crowns through dental technology is a basic function of dentistry. The morphology of tooth crowns is the most important parameter for evaluating its acceptability. The procedures were divided into four steps: tooth collection, scanning skills, use of mathematical methods and software, and machine learning calculation. Materials and methods: Dental plaster rods were prepared. The effective data collected were to classify 121 teeth (15th tooth position), 342 teeth (16th tooth position), 69 teeth (21st tooth position), and 89 teeth (43rd tooth position), for a total of 621 teeth. The procedures are divided into four steps: tooth collection, scanning skills, use of mathematical methods and software, and machine learning calculation. Results: The area under the curve (AUC) value was 0, 0.5, and 0.72 in this study. The precision rate and recall rate of micro-averaging/macro-averaging were 0.75/0.73 and 0.75/0.72. If we took a newly carved tooth picture into the program, the current effectiveness of machine learning was about 70%-75% to evaluate the quality of tooth morphology. Through the calculation and analysis of the two different concepts of micro-average/macro-average and AUC, similar values could be obtained. Conclusion: This study established a set of procedures that can judge the quality of hand-carved plaster sticks and teeth, and the accuracy rate is about 70%-75%. It is expected that this process can be used to assist dental technicians in judging the pros and cons of hand-carved plaster sticks and teeth, so as to help dental technicians to learn the tooth morphology more effectively.

Fabrication of CuYO2 Nanofibers by Electrospinning and Applied to Hydrogen Harvest.

Hydrogen can be employed as an alternative renewable energy source in response to climate change, global warming, and the energy problem. Methanol gas steam reforming (SRM) is the major method used in industry to produce hydrogen. In the SRM process, the catalyst nature offers benefits such as low cost, simplicity, and quickness. In this work, delafossite copper yttrium oxide (CuYO2) nanofibers were successfully prepared by electrospinning. The prepared CuYO2 nanofibers have different physical and chemical properties including thermoelectric behavior. The electrospinning method was used to produce as-spun fibers and annealed in an air atmosphere to form Cu2Y2O5 fibers; then, Cu2Y2O5 fibers were annealed in a nitrogen atmosphere to form CuYO2 nanofibers. X-ray diffraction studies and thermogravimetric and transmission electron microscope analysis confirmed the formation of CuYO2 nanofibers. The CuYO2 nanofibers were applied to methanol steam reforming for hydrogen production to confirm their catalytic ability. The CuYO2 nanofibers exhibited high catalytic activity and the best hydrogen production rate of 1967.89 mL min-1 g-cat-1 at 500 °C. The highly specific surface area of CuYO2 nanofibers used in steam reforming reactions could have significant economic and industrial implications. The performance of these CuYO2 nanofibers in hydrogen generation could be very important in industries with a global economic impact. Furthermore, the H2 production performance increases at higher reaction temperatures.

Analysis of Melt Front Behavior of a Light Guiding Plate during the Filling Phase of Micro-Injection Molding.

When the size of a liquid crystal display (LCD) increases, the light guiding plate (LGP) as the main part of the LCD must adopt a wedge-shaped plate to reduce its weight (the thickness of the LGP decreases because of this) and guide the light to the LCD screen. Micro-injection molding (MIM) is commonly used to manufacture LGPs. During the filling phase of MIM, the entire entering polymer melt front of the LGP should reach the end of the mold cavity at the same time. In this way, there will be no shrinkage or warpage of the LGP in its subsequent application, but it is difficult for the wedge-shaped LGP to meet these requirements. Therefore, the authors hoped to investigate MIM process parameters to change this situation. Otherwise, the LGP is easily deformed during the manufacturing process. Flow characteristics of LGPs were investigated during the filling phase of MIM in this study. Experimental and 3D numerical simulations were used to analyze the hysteresis, i.e., the advance of the polymer melt front of the LGP in MIM. Study results showed that a low injection speed caused a hysteresis effect of the plastic melt front, the solution was to increase the injection speed to improve the situation and an injection speed of 10 cm/s could achieve uniformity of the melt front in MIM. The research results showed that the filling situation of the LGP of MIM in the experiment was very close to that of the 3D numerical simulation.

Analysis of the Warpage Phenomenon of Micro-Sized Parts with Precision Injection Molding by Experiment, Numerical Simulation, and Grey Theory.

In this study, we determined the effects of design and processing parameters of precision injection molding (PIM) to minimize warpage phenomena of micro-sized parts using various plastics (polyoxymethylene (POM), acrylonitrile-butadiene-styrene (ABS), polypropylene (PP), polyamide (PA), and ABS+ polycarbonate (PC)). We applied a numerical simulation (Moldflow) to determine the runner's balance in multi-cavities of the micro-sized part and simulate the warpage phenomenon of micro-parts with PIM. We used simulation data to fabricate a steel mold by computer numerical control (CNC) machining. In this, we study manufactured a micro-sized part and measured its warpage value using various PIM process parameters (melt temperature, mold temperature, injection pressure, and filling time). In order to obtain optimal results (i.e., minimum warpage), we employed the Taguchi method and grey theory to discern the influence of each process parameter on PIM. Finally, we determined that the most significant PIM process parameter influencing the warpage phenomenon of micro-sized parts was the mold temperature, regardless of whether in terms of the experimental results, numerical simulations, or grey theory. The PA material had the most suitable properties for application for micro-sized parts, regardless of whether in terms of experimental results, numerical simulations, or grey theory for PIM. This study also illustrates that micro-sized parts can be fabricated by PIM without the use of micro-injection molding, and we determined that the mold temperature required for molding does not need to be higher than the glass-transition temperature of the material.

Optimal Processing Parameters of Transmission Parts of a Flapping-Wing Micro-Aerial Vehicle Using Precision Injection Molding.

In this study, we designed and fabricated transmission parts for a flapping-wing micro-aerial vehicle (FW-MAV), which was fabricated by precision injection molding, and analyzed its warpage phenomena. First, a numerical simulation (Moldflow) was used to analyze the runner balance and temperature, pressure, and stress distributions of the base, gears, and linkage of the transmission structures in an FW-MAV. These data were then applied to fabricate a steel mold for an FW-MAV. Various process parameters (i.e., injection temperature, mold temperature, injection pressure, and packing time) for manufacturing transmission parts for the FW-MAV by precision injection molding were compared. The Taguchi method was employed to determine causes of warpage in the transmission parts. The experimental results revealed that the causes of warpage in the transmission parts were, in order of importance, the mold temperature, injection pressure, packing time, and injection temperature. After the transmission parts were assembled on the FW-MAV, experiments revealed that the MAV could achieve a flight time of 180 s. Mass production of the FW-MAV by precision injection molding could potentially produce substantial savings in time, manpower, and cost.

Optimized Micro-Pattern Design and Fabrication of a Light Guide Plate Using Micro-Injection Molding.

This study examined the uniformity of illuminance field distributions of light guide plates (LGPs). First, the authors designed microstructural patterns on the surface of an LGP. Then, a mold of the LGP with the optimal microstructural design was fabricated by a photolithography method. Micro-injection molding (µIM) was used to manufacture the molded LGPs. µIM technology can simultaneously manufacture large-sized wedge-shaped LGPs and micro-scale microstructures. Finally, illuminance values of the field distributions of the LGPs with various microstructures were obtained through optical field measurements. This study compared the illuminance field distributions of LGPs with various designs and structures, which included LGPs without and those with microstructure on the primary design and the optimal design. The average illuminance of the LGP with microstructures and the optimal design was roughly 196.1 cd/m2. Its average illuminance was 1.3 times that of the LGP without microstructures. This study also discusses illuminance field distributions of LGPs with microstructures that were influenced by various µIM process parameters. The mold temperature was found to be the most important processing parameter affecting the illuminance field distribution of molded LGPs fabricated by µIM. The molded LGP with microstructures and the optimal design had better uniformity than that with microstructures and the primary design and that without microstructures. The uniformity of the LGP with microstructures and the optimal design was roughly 86.4%. Its uniformity was nearly 1.65 times that of the LGP without microstructures. The optimized design and fabrication of LGPs with microstructure exhibited good uniformity of illuminance field distributions.

Comparison of Dental Surface Image Registration and Fiducial Marker Registration: An In Vivo Accuracy Study of Static Computer-Assisted Implant Surgery.

This study compared the accuracy of static computer-assisted implant surgery (sCAIS) planned through dental surface image registration and fiducial marker registration. Stone models of 30 patients were converted into digital dental casts by using a desktop scanner. Cone-beam computed tomography (CBCT) was performed and superimposed to the digital dental casts with two methods: matching the dental surface images or matching the fiducial markers on a stereolithographic radiographic template. Following the implant planning, stereolithographic surgical guides were fabricated, and 56 fully guided implants were inserted by the same doctor. Deviations between planned and inserted implants were measured and compared using postoperative CBCT images. After adjustment for other potential influencing factors, compared with the fiducial marker registration group, significantly larger mean lateral deviations were noted in the dental surface registration group at both the implant platform and apex (p = 0.0188 and 0.0371, respectively). However, the mean lateral deviations for the dental surface registration (0.83 ± 0.51 mm at implant platform and 1.24 ± 0.68 mm at implant apex) were comparable to the literature. In conclusion, our findings indicate that although sCAIS planned using dental surface image registration was not statistically as accurate as that using fiducial marker registration, its accuracy was satisfactory for clinical use.

Bioactivity and Bone Cell Formation with Poly-ε-Caprolactone/Bioceramic 3D Porous Scaffolds.

This study applied poly-ε-caprolactone (PCL), a biomedical ceramic powder as an additive (nano-hydroxyapatite (nHA) or ß-tricalcium diphosphate (ß-TCP)), and sodium chloride (NaCl) and ammonium bicarbonate ((NH4)HCO3) as porogens; these stuffs were used as scaffold materials. An improved solvent-casting/particulate-leaching method was utilized to fabricate 3D porous scaffolds. In this study we examined the physical properties (elastic modulus, porosity, and contact angle) and degradation properties (weight loss and pH value) of the 3D porous scaffolds. Both nHA and ß-TCP improved the mechanical properties (elastic modulus) of the 3D porous scaffolds. The elastic modulus (0.15~1.865 GPa) of the various composite scaffolds matched that of human cancellous bone (0.1~4.5 GPa). Osteoblast-like (MG63) cells were cultured, a microculture tetrazolium test (MTT) was conducted and alkaline phosphatase (ALP) activity of the 3D porous scaffolds was determined. Experimental results indicated that both nHA and ß-TCP powder improved the hydrophilic properties of the scaffolds. The degradation rate of the scaffolds was accelerated by adding nHA or ß-TCP. The MTT and ALP activity tests indicated that the scaffolds with a high ratio of nHA or ß-TCP had excellent properties of in vitro biocompatibility (cell attachment and proliferation).

Optimization Shape-Memory Situations of a Stimulus Responsive Composite Material.

In these times of Industrial 4.0 and Health 4.0, people currently want to enhance the ability of science and technology, to focus on patient aspects. However, with intelligent, green energy and biomedicine these days, traditional three-dimensional (3D) printing technology has been unable to meet our needs, so 4D printing has now arisen. In this research, a shape-memory composite material with 3D printing technology was used for 4D printing technology. The authors used fused deposition modeling (FDM) to print a polylactic acid (PLA) strip onto the surface of paper to create a shape-memory composite material, and a stimulus (heat) was used to deform and recover the shape of this material. The deformation angle and recovery angle of the material were studied with various processing parameters (heating temperature, heating time, pitch, and printing speed). This research discusses optimal processing related to shape-memory situations of stimulus-responsive composite materials. The optimal deformation angle (maximum) of the stimulus-responsive composite material was found with a thermal stimulus for an optimal heating temperature of 190 °C, a heating time of 20 s, a pitch of 1.5 mm, and a printing speed of 80 mm/s. The optimal recovery angle (minimum) of this material was found with a thermal stimulus for an optimal heating temperature of 170 °C, a heating time of 90 s, a pitch of 2.0 mm, and a printing speed of 80 mm/s. The most important factor affecting both the deformation and recovery angle of the stimulus-responsive composite material was the heating temperature.

Hybrid ZnO/chitosan antimicrobial coatings with enhanced mechanical and bioactive properties for titanium implants.

A biocomposite coating comprising chitosan and ZnO deposited on a porous Ti oxide is developed to avoid orthopedic and dental implant-related infections. The coating comprised of an inner layer of nanoporous TiO2 and the outer layer of the chitosan matrix with ZnO nanoparticles. Microbiological tests show that chitosan coating is effective against Escherichia coli (E. coli), however, its ability to inhibit bacterial adhesion is very limited. A 1.2-fold increase in the antibacterial activity of chitosan/ZnO coating against E. coli was detected as compared to the chitosan coating alone, and the chitosan/ZnO efficiently inhibited biofilm formation. In addition, the chitosan/ZnO coating exhibited improved bioactivity compared to the chitosan coating. The improvement in antibacterial properties and bioactivity of the chitosan/ZnO coating is attributed to the release of Zn2+ ions. The critical force of scratching the chitosan/ZnO coating was approximately twice that of the chitosan coating. The potentiodynamic polarization results confirmed that the corrosion resistance of the implant with ZnO/chitosan/Ti structure was improved. In addition, cytocompatibility evaluation indicated that the chitosan/ZnO coating has good cytocompatibility in MG-63 cells as compared to pure Ti.

Long-Term Oral Toxicity and Anti-osteoporotic Effect of Sintered Dicalcium Pyrophosphate in Rat Model of Postmenopausal Osteoporosis.

Sintered dicalcium pyrophosphate (SDCP), a synthetic pyrophosphate analog, has shown potential for the management of osteoporosis. The long-term oral toxicity and anti-osteoporotic effect of SDCP in a postmenopausal osteoporosis rat model were evaluated in this study. SDCP was orally administered to bilateral ovariectomized (OVX) Wistar rats at a dose of 0.75 mg/kg daily for 24 weeks following by 2 weeks of observation. There were no abnormal findings in clinical signs of toxicity, food consumption, body weight, blood examination, necropsy, and histological inspection attributable to the ingestion of SDCP. The serum level of type I collagen fragments, a bone resorption marker, decreased in SDCP-treated rats, and the bone formation markers alkaline phosphatase, osteocalcin, and osteopontin significantly decreased. These findings indicate that the bone turnover rate decreased in SDCP-treated animals. Relative to OVX rats, the increase in serum tartrate-resistant acid phosphatase 5b level represents an increase in bony tissues in the SDCP-treated rats. Histological examinations of distal femoral metaphyses further revealed that the ingestion of SDCP improved the trabecular bone architecture and decreased bone porosity. Analysis of limb bone ashes showed a significant increase in bone mineral content. Our results show that SDCP inhibits bone resorption to restore bone mass in OVX rats without deleterious effects, and therefore that SDCP has potential in the management of osteoporosis.

Strontium-impregnated bioabsorbable composite for osteoporotic fracture fixation.

Osteoporosis impairs the bone-healing process as well as bone fracture fixation. The intervention of osteoporosis is considered to be one part of bone fracture treatment. Thus, orthopedic fixators impregnated with antiosteoporosis regimens will improve fracture fixation in osteoporotic bone. In this study, the strontium (Sr) and calcium phosphate ceramic (CPC) were mixed first and then mixed with poly(ε-caprolactone) (PCL) to fabricate a bioactive and bioabsorbable bone fixators. The prepared Sr-CPC/PCL screws were implanted into the distal femur of ovariectomized rabbits. The results showed that Sr-CPC/PCL composite had the appropriate mechanical properties, good biocompatibility, and radio-opacity. The Sr addition created a porous structure and accelerated the degradation of bone screws, but the degradation products did not acidify the surrounding environment. For osteoporotic animals, favorable osteointegration around the Sr-CPC/PCL screws was found, and the total porosity of trabecular bone was decreased under the inspections of micro-computerized tomography. Compared with PCL or CPC/PCL screw, animals which received Sr-CPC/PCL were found to have better results in terms of trabecular number, thickness, and separation. This study reveals that the Sr-impregnated bone fixator improves osseointegration in osteoporotic animals. Sr-CPC/PCL composite is a good candidate material for osteofixation in osteoporotic patients.