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Integration between the phases of computer-based guided dental implant surgery can be used to optimize oral rehabilitation. Two new surgical guides prepared by using the 3D metal and polymer printing technology are presented for immediate implant loading and definitive fixed prosthesis construction in flapless dental implant surgery. Nine implants and 2 fixed prostheses were installed in 2 completely edentulous adult patients by using a metallopolymer surgical guide with a metal central bar attached to a polymer seal or a metal guide. Virtual planning was used to design the 3D printed surgical guides, which were then constructed by using selective laser sintering (SLM) and selective laser melting (SLS). The 3D printed surgical guides oriented the surgical placement of the implants and were welded to the abutments and attached to the denture framework. The technique allowed implants and prostheses to be installed on the same day., (Copyright © 2022 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

It is crucial to monitor the levels of Non-Ionizing Radiation (NIR) to which the general population may be exposed and compare them to the limits defined in the current standards, in view of the rapid rise of communication services and the prospects of a connected society. A high number of people visits shopping malls and since these locations usually have several indoor antennas close to the public, it is therefore a kind of place that must be evaluated. Thus, this work presents measurements of the electric field in a shopping mall located in Natal, Brazil. We proposed a set of six measurement points, following two criteria: places with great the flow of people and the presence of one or more Distributed Antenna System (DAS), co-sited or not with WiFi access points. Results are presented and discussed in terms of the distance to DAS (conditions: near and far) and flow density of people in the mall (scenarios: low and high number of people). The highest peaks of electric field measured were 1.96 and 3.26 V/m, respectively corresponding to 5% and 8% of the limits defined by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the Brazilian National Telecommunication Agency (ANATEL).

Cancer is the second leading cause of death globally and early diagnosis is the best strategy to reduce mortality risk. Biosensors to detect cancer biomarkers are based on various principles of detection, including electrochemical, optical, electrical, and mechanical measurements. Despite the advances in the identification of biomarkers and the conventional 2D manufacturing processes, detection methods for cancers still require improvements in terms of selectivity and sensitivity, especially for point-of-care diagnosis. Three-dimensional printing may offer the features to produce complex geometries in the design of high-precision, low-cost sensors. Three-dimensional printing, also known as additive manufacturing, allows for the production of sensitive, user-friendly, and semi-automated sensors, whose composition, geometry, and functionality can be controlled. This paper reviews the recent use of 3D printing in biosensors for cancer diagnosis, highlighting the main advantages and advances achieved with this technology. Additionally, the challenges in 3D printing technology for the mass production of high-performance biosensors for cancer diagnosis are addressed.

This study was designed to evaluate the accuracy of a novel computer-designed and selectively laser sintered surgical guide for flapless dental implant placement in the edentulous jaw. Fifty dental implants were placed in 11 patients with at least 1 totally edentulous jaw. Initially, cone-beam computed tomography (CBCT) was performed in each patient to define the virtual position of the dental implants based on the assessment of bone availability and the proposed dental prosthesis. After virtual planning, 3D surgical guides were printed using selective laser sintering. CBCT was repeated after the surgery, and the pre- and postoperative images were overlapped in computer-assisted design software to compare the planned and actual positions of the dental implants using a 1-sample t test. The mean ± angular standard deviation between the long axes of the planned and final dental implant positions was 4.58° ± 2.85°; the linear deviation in the coronal position was 0.87 ± 0.49 mm and in the apical region of the dental implants was 1.37 ± 0.69 mm. These differences were statistically significant (P < .001). The proposed modifications reduced the deviations, resulting in an improvement in the technique. We were able to place implants and temporary prostheses using the present protocol, taking into account the differences between the planned and final positions of the dental implants.

The development of blood-interacting surfaces is critical to fabricate biomaterials for medical use, such as prostheses, implants, biosensors, and membranes. For instance, thrombosis is one of the leading clinical problems when polymer-based materials interact with blood. To overcome this limitation is necessary to develop strategies that limit platelets adhesion and activation. In this work, hyaluronan (HA)/chitosan (Chi) based-films, recently reported in the literature as platforms for tumor cell capture, were developed and, subsequently, functionalized with sulfated chitosan (ChiS) using a layer-by-layer technique. ChiS, when compared to native Chi, presents the unique abilities to confer anti-thrombogenic properties, to reduce protein adsorption, and also to limit calcification. Film physicochemical characterization was carried out using FTIR and XPS for chemical composition assessment, AFM for the surface morphology, and contact angle for hydrophilicity evaluation. The deposition of ChiS monolayer promoted a decrease in both roughness and hydrophilicity of the HA/Chi films. In addition, the appearance of sulfur in the chemical composition of ChiS-functionalized films confirmed the film modification. Biological assay indicated that the incorporation of sulfated groups limited platelet adhesion, mainly because a significant reduction of platelets adhesion to ChiS-functionalized films was observed compared to HA/Chi films. On balance, this work provides a new insight for the development of novel antithrombogenic biomaterials, opening up new possibilities for devising blood-interaction surfaces., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Three-dimensional cellular aggregates can mimic the natural microenvironment of tissues and organs and obtaining them through controlled and reproducible processes is mandatory for scaling up and implementing drug cytotoxicity and efficacy tests, as well as tissue engineering protocols. The purpose of this work was to develop and evaluate the performance of a device with two different geometries fabricated by additive manufacturing. The methodology was based on casting a microwell array insert using a non-adhesive hydrogel to obtain highly regular microcavities to standardize spheroid formation and morphology. Spheroids of dental pulp stem cells, bone marrow stromal cells and embryonic stem cells showing high cell viability and average diameters of around 253, 220, and 500 μm, respectively, were produced using the device with the geometry considered most adequate. The cell aggregates showed sphericity indexes above 0.9 and regular surfaces (solidity index higher than 0.96). Around 1000 spheroids could be produced in a standard six-well plate. Overall, these results show that this method facilitates obtaining a large number of uniform, viable spheroids with pre-specified average diameters and through a low-cost and reproducible process for a myriad of applications., (Copyright © 2022 Elsevier B.V. All rights reserved.)

In this article, a recent formulation for real-time simulation is developed combining the strain energy density of the Spring Mass Model (SMM) with the equivalent representation of the Strain Energy Density Function (SEDF). The resulting Equivalent Energy Spring Model (EESM) is expected to provide information in real-time about the mechanical response of soft tissue when subjected to uniaxial deformations. The proposed model represents a variation of the SMM and can be used to predict the mechanical behavior of biological tissues not only during loading but also during unloading deformation states. To assess the accuracy achieved by the EESM, experimental data was collected from liver porcine samples via uniaxial loading and unloading tensile tests. Validation of the model through numerical predictions achieved a refresh rate of 31 fps (31.49 ms of computation time for each frame), achieving a coefficient of determination R 2 from 93.23% to 99.94% when compared to experimental data. The proposed hybrid formulation to characterize soft tissue mechanical behavior is fast enough for real-time simulation and captures the soft material nonlinear virgin and stress-softened effects with high accuracy.

To meet the demands of the market and society, the development of structured polymeric materials for application in the medical field is constantly increasing. Over the last decades, metallic silver nanoparticles have been explored due to their antimicrobial action. Here, we aimed to incorporate metallic silver nanoparticles into polymeric pieces obtained by additive manufacture via a chemical route involving silver nitrate and sodium borohydride. Polyamide 12 membranes were obtained by selective laser sintering, which was followed by washing, pretreatment, and functionalization with the alkoxides tetraethylorthosilicate and 3-aminopropyl tetraethoxysilane. For nanoparticle preparation and incorporation, a chemical route was tested under different conditions. The samples were characterized by techniques, such as X-ray diffraction, ultraviolet-visible spectroscopy, and infrared vibrational spectroscopy. Nanoparticle formation and incorporation into the polyamide 12 membranes were demonstrated by the absorbance band at 420 nm, which indicated that the particles measured between 10 and 50 nm in size; by the X-ray diffraction peaks at 2θ = 38, 44, and 64°, which are typical of crystalline silver; and by vibrational spectroscopy, which evidenced that the nanoparticles interacted with the polyamide 12 nitrogen groups. Polyamide 12 membranes containing metallic silver nanoparticles have promising biomedical applications as antimicrobial wound dressings associated with drug carriers., Competing Interests: Conflict of interestThe authors declare no competing interests., (© The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2022.)

Background: Nerve injuries are debilitating, leading to long-term motor deficits. Remyelination and axonal growth are supported and enhanced by growth factor and cytokines. Combination of nerve guidance conduits (NGCs) with adipose-tissue-derived multipotent mesenchymal stromal cells (AdMSCs) has been performing promising strategy for nerve regeneration., Methods: 3D-printed polycaprolactone (PCL)-NGCs were fabricated. Wistar rats subjected to critical sciatic nerve damage (12-mm gap) were divided into sham, autograft, PCL (empty NGC), and PCL + MSCs (NGC multi-functionalized with 10 6 canine AdMSCs embedded in heterologous fibrin biopolymer) groups. In vitro, the cells were characterized and directly stimulated with interferon-gamma to evaluate their neuroregeneration potential. In vivo, the sciatic and tibial functional indices were evaluated for 12 weeks. Gait analysis and nerve conduction velocity were analyzed after 8 and 12 weeks. Morphometric analysis was performed after 8 and 12 weeks following lesion development. Real-time PCR was performed to evaluate the neurotrophic factors BDNF, GDNF, and HGF, and the cytokine and IL-10. Immunohistochemical analysis for the p75 NTR neurotrophic receptor, S100, and neurofilament was performed with the sciatic nerve., Results: The inflammatory environment in vitro have increased the expression of neurotrophins BDNF, GDNF, HGF, and IL-10 in canine AdMSCs. Nerve guidance conduits multi-functionalized with canine AdMSCs embedded in HFB improved functional motor and electrophysiological recovery compared with PCL group after 12 weeks. However, the results were not significantly different than those obtained using autografts. These findings were associated with a shift in the regeneration process towards the formation of myelinated fibers. Increased immunostaining of BDNF, GDNF, and growth factor receptor p75 NTR was associated with the upregulation of BDNF, GDNF, and HGF in the spinal cord of the PCL + MSCs group. A trend demonstrating higher reactivity of Schwann cells and axonal branching in the sciatic nerve was observed, and canine AdMSCs were engrafted at 30 days following repair., Conclusions: 3D-printed NGCs multi-functionalized with canine AdMSCs embedded in heterologous fibrin biopolymer as cell scaffold exerted neuroregenerative effects. Our multimodal approach supports the trophic microenvironment, resulting in a pro-regenerative state after critical sciatic nerve injury in rats.

We report on layer-by-layer (LbL) films of chitosans (CHI) and hyaluronic acid (HA) whose properties could be controlled by employing chitosans with different degrees of deacetylation (DD¯ ≈ 85%; 65%; 40%) and high average molecular weight (ca. 10 6  g/mol). In spite of their high molecular weight, these chitosans are soluble within a wide pH range, including physiological pH. HA/CHI LbL films produced from polymer solutions at pH 4.5 were thinner, smoother, more hydrophilic than those prepared at pH 7.2. This is attributed to the more extended conformation adopted by chitosan due to its very high charge density at low pH, favoring a compact chain packing during the film formation and resulting in lower film thickness and roughness. The smoother HA/CHI LbL films obtained at pH 4.5 were effective against Escherichia coli, while the thicker, rougher LbL films fabricated at pH 7.2 could be used in the controlled released of Rose Bengal dye. In summary, the tuning of only two parameters, i.e. solution pH and DD¯ of chitosans, provides access to a library of HA/CHI LbL films for tailored, diversified applications., Competing Interests: Declaration of competing interest There are no conflicts to declare., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has spread through more than 180 countries, leading to diverse health systems overload around the world. Because of the high number of patients and the supply chain disruption, it generated a shortage of medical devices and personal protective equipment. In this context, initiatives from the additive manufacturing community emerged to fight the lack of devices. Diverse designs were produced and are currently being used in hospitals by patients and health workers. However, as some devices must follow strict standards, these products may not fulfill these standards. Therefore, to ensure the user's health, there is a need for understanding each device, their usage, and standards. This study reviews the use of additive manufacturing during COVID-19 pandemic. It gathers the source of several 3D printed devices such as face shields, face masks, valves, nasopharyngeal swabs, and others, discussing their use and regulatory issues. In this regard, the major drawbacks of the technology, addressed for the next pandemic scenario, are highlighted. Finally, some insights of the future of additive manufacturing during emergency are given and discussed., Competing Interests: Conflicts of interestThe authors declare that they have no conflict of interest., (© Springer Nature Switzerland AG 2020.)

Bone is a dynamic tissue that can always rebuild itself by modeling and remodeling to maintain functionality. This tissue is responsible for several vital functions in the body, such as providing structural support for soft tissues and the body, being the central region of hematopoiesis in human adults, and contributing to mineral homeostasis. Besides, it has an innate ability of auto-regeneration when damaged. All of these processes involve several molecular cues related to biochemical and mechanical stimulus. However, when the lesion is complicated or too big, it is necessary to intervene surgically, which may not effectively solve the problem. Bone tissue engineering seeks to provide resources to resolve these clinical issues and has been advancing in recent years, presenting promising devices for bone tissue repair. The understanding of some important biofactors and bone stem-cells influence might be crucial for an effective regenerative medicine, since bone is one of the most transplanted tissues. So, the purpose of this article is to provide an overview of the bone tissue, including the role of stem cells and some of the bioactive molecules associated with these processes. Finally, we will suggest future directions for bone tissue engineering area that might be helpful in order to produce biomimetic bone substitutes that become a real alternative to translational medicine.

Background: Cranial reconstruction surgery is a procedure used as an attempt to reestablish the cranial bone anatomy. This study evaluates the symptomatic and aesthetic improvement of patients with cranial defects secondary to decompressive craniectomies after cranial reconstruction with customized polymethyl methacrylate (PMMA) prostheses. Secondly, we aim to divide our experience in the production of these prostheses with a low-cost method., Methods: A prospective study was carried out with patients submitted to cranioplasty at the Hospital da Restauração between 2014 and 2017. A total of 63 cranioplasties were performed using customized PMMA prosthesis produced by 3D impression molds. All patients underwent a functional and aesthetic evaluation questionnaire in the preoperative period and in the sixth postoperative month., Results: Sixty-three patients underwent cranioplasty with a mean age of 33 years, ranging from 13 to 58 years, 55 males and 8 females. The mean area of the defect was 147 cm 2 . The mean postoperative follow-up of the patients was 21 months, ranging from 6 to 33 months. Fifty-five patients attended the 6-month postoperative consultation. All patients presented symptomatic improvement after reconstruction of the skull. The infection rate was 3.2%, 4.8% of extrusion, 1.6% of prosthesis fracture, 7.9% of extradural hematoma, 17.4% of reoperation, 5% of wound dehiscence, and 4.8% of removal of the prosthesis., Conclusion: Cranioplasty, with a customized PMMA prosthesis, improved the symptoms and aesthetic appearance of all operated patients. The use of prototypes to customize cranial prostheses facilitated the operative technique and allowed the recovery of a cranial contour very close to normal., Competing Interests: There are no conflicts of interest.

Poly(3-hydroxybutyrate) (PHB) is a biodegradable and thermoprocessable biopolymer, making it a promising candidate for applications in tissue engineering. In the present study a structural characterization and in vitro evaluation were performed on PHB scaffolds produced by additive manufacturing via selective laser sintering (SLS), followed by post-printing functionalization with osteogenic growth peptide (OGP) and its C-terminal sequence OGP(10-14). The PHB scaffolds were characterized, including their morphology, porosity, thermal and mechanical properties, moreover OGP release. The results showed that SLS technology allowed the sintering of the PHB scaffolds with a hierarchical structure with interconnected pores and intrinsic porosity (porosity of 55.8 ± 0.7% and pore size in the 500-700 μm range), and good mechanical properties. Furthermore, the SLS technology did not change thermal properties of PHB polymer. The OGP release profile showed that PHB scaffold promoted a controlled release above 72 h. In vitro assays using rat bone marrow stem cells showed good cell viability/proliferation in all the PHB scaffolds. Additionally, SEM images suggested advanced morphological differentiation in the groups containing osteogenic growth peptide. The overall results demonstrated that PHB biopolymer is potential candidate for 3D printing via SLS technology, moreover the OGP-containing PHB scaffolds showed ability to sustain cell growth to support tissue formation thereby might be considered for tissue-engineering applications., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Purpose: The fixation of combined mandibular fractures, especially symphyseal-condylar fractures, although occurring commonly and having a higher complication rate in the clinic, is rarely investigated regarding predictable therapeutic approaches. Thus this study's aim was to assess different forms of condylar fixation when combined with symphyseal fracture fixation., Materials and Methods: Using finite element models, we analyzed the stress distribution that occurs when a condylar fracture is fixed with 1 miniplate, 2 miniplates, or a trapezoidal condylar miniplate and when a symphyseal fracture is fixed with 2 parallel plates, 2 perpendicular plates, or 2 lag screws. The null hypothesis was that there would be no differences among the different fixation techniques., Results: The results showed a stress concentration in the anterior region of the condyle, close to the sigmoid notch. Moreover, adequate fixation in the symphysis could result in less tension at the condylar region. Therefore, when the symphysis was fixed with a lag-screw technique, condylar fixation was less required, showing a more adequate stress distribution when the condyle was fixed with 1 or 2 plates. Conversely, when the symphyseal fixation was less effective, by use of perpendicular plates, there was a change in the stress distribution at the condylar region, altering fixation behavior and resulting in more tension and displacement in the condyle, especially when a trapezoidal plate was used., Conclusions: A lag screw and parallel double plates appear to be suitable for symphyseal fixation, whereas 2 straightly positioned plates and a trapezoidal plate are suitable for condylar fixation. However, the combination of perpendicular plates in symphyseal fixation and a trapezoidal plate in condylar fixation showed an altered stress distribution., (Copyright © 2017 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

This study verified the difference between two methods of forensic facial approximation (FFA) regarding recognition and resemblance rates. Three-dimensional models of skulls were obtained from computerized tomography (CT) scans of two subjects (targets). Two manual FFAs were performed for each target, by applying two different guidelines for the facial structures (what we called "American method" (AM) and "Combined method" (CM)). Unfamiliar assessors evaluated the sculptures by recognition and resemblance tests. The AM was that which allowed more correct responses of recognition and higher resemblance's scores for the male target (p < 0.001). Regarding guidelines for modeling characteristics of the face, the ones that are practical and easily performed for sculptures, such as the length of the anterior nasal spine multiplied by 3 for nose prediction, may offer better results in terms of resemblance., (© 2017 American Academy of Forensic Sciences.)

Facial soft tissue thicknesses (FSTT) are important guidelines for modeling faces from skull. Amid so many FSTT data, Forensic artists have to make a subjective choice of a dataset that best meets their needs. This study investigated the performance of four FSTT datasets in the recognition and resemblance of Brazilian living individuals and the performance of assessors in recognizing people, according to sex and knowledge on Human Anatomy and Forensic Dentistry. Sixteen manual facial approximations (FAs) were constructed using three-dimensional (3D) prototypes of skulls (targets). The American method was chosen for the construction of the faces. One hundred and twenty participants evaluated all FAs by means of recognition and resemblance tests. This study showed higher proportions of recognition by FAs conducted with FSTT data from cadavers compared with those conducted with medical imaging data. Targets were also considered more similar to FAs conducted with FSTT data from cadavers. Nose and face shape, respectively, were considered the most similar regions to targets. The sex of assessors (male and female) and the knowledge on Human Anatomy and Forensic Dentistry did not play a determinant role to reach greater recognition rates. It was possible to conclude that FSTT data obtained from imaging may not facilitate recognition and establish acceptable level of resemblance. Grouping FSTT data by regions of the face, as proposed in this paper, may contribute to more accurate FAs., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)