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The global market for dental implants is constantly evolving. To overcome the limitations of conventional strategies - invasive surgeries and bone loss around the implant-, new approaches, namely the development of CAD/CAM customized implants, are emerging as promising solutions for replacing missing teeth, thus avoiding destruction of bone by drilling it. Despite the efforts that are being carried out, the designing, including image acquisition, and manufacturing efficacy of such rehabilitation therapy is not easily found in the literature. In this sense, this research work aimed to assess the errors associated with the image acquisition, treatment and manufacturing of Customized Root-Analogue Implants (CRAI). The experimental procedure, carried out in a dog cadaveric mandible, encompassed the image acquisition and treatment and the subsequent manufacturing of four different CRAI. Two Image acquisition methods (CBCT and X-ray), and different software for their treatment were used, and the final CRAI were manufactured by Computer Numerical Control. Results revealed the CBCT scan allowed to properly visualize the original teeth contours. However, all the obtained teeth geometries presented smaller surface areas when compared to the original teeth indicating however a systematic predictable error. On the other hand, when comparing the surface area of the digital and the manufactured teeth, very small differences were observed, which indicates that the CNC manufacturing technique is a promising solution for such applications. When placing the produced CRAI in the dog mandible it was possible to observe a lack of congruency between the CRAI and bone, mainly due to image acquisition process errors and the destruction of the periodontal ligament during the soft tissues removal process. Thus, CBCT images seem to be a feasible route to design root-analogue implants, and, if needed, a compensation strategy for the systematic image acquisition error may be implemented., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Zirconia is becoming reckoned as a promising solution for different applications, in particular those within the dental implant investigation field. It has been proved to successfully overcome important limitations of the commonly used titanium implants. The adhesion of microorganisms to the implants, in particular of bacteria, may govern the success or the failure of a dental implant, as the accumulation of bacteria on the peri-implant bone may rapidly evolve into periodontitis. However, bacterial adhesion on different zirconia architectures is still considerably unknown. Therefore, the adhesion of Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa to zirconia surfaces with different finishings was evaluated and compared to a titanium surface. The adhesion interaction between S. aureus and P. aeruginosa was also evaluated using a co-culture since these bacteria are infamous due to their common presence in chronic wound infections. Results showed that different bacterium species possess different properties which influence their propensity to adhere to different roughness levels and architectures. E. coli revealed a higher propensity to adhere to zirconia channelled surfaces (7.15 × 10 6  CFU/mL), whereas S. aureus and P. aeruginosa adhered more to the titanium control group (1.07 × 10 5  CFU/mL and 8.43 × 10 6  CFU/mL, respectively). Moreover, the co-culture denoted significant differences on the adhesion behaviour of bacteria. Despite not having shown an especially better behaviour regarding bacterial adhesion, zirconia surfaces with micro-channels are expected to improve the vascularization around the implants and ultimately enhance osseointegration, thus being a promising solution for dental implants., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Tooth loss is a problem that affects both old and young people. It may be caused by several conditions, such as poor oral hygiene, lifestyle choices or even diseases like periodontal disease, tooth grinding or diabetes. Nowadays, replacing a missing tooth by an implant is a very common process. However, many limitations regarding the actual strategies can be enumerated. Conventional screwed implants tend to induce high levels of stress in the peri-implant bone area, leading to bone loss, bacterial bio-film formation, and subsequent implant failure. In this sense, root-analogue dental implants are becoming promising solutions for immediate implantation due to their minimally invasive nature, improved bone stress distribution and because they do not require bone drilling, sinus lift, bone augmentation nor other traumatic procedures. The aim of this study was to analyse and compare, by means of FEA, the stress fields of peri-implant bone around root-analogue and screwed conventional zirconia implants. For that purpose, one root-analogue implant, one root-analogue implant with flaps, two conventional implants (with different threads) and a replica of a natural tooth were modelled. COMSOL was used to perform the analysis and implants were subjected to two simultaneous loads: 100 N axially and 100 N oblique (45°). RESULTS: revealed that root-analogue implants, namely with flaps, should be considered as promising alternatives for dental implant solutions since they promote a better stress distribution in the cortical bone when compared with conventional implants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The Ti6Al4V alloy constitutes an alternative choice to the most common metal-polymer solutions for total hip arthroplasty (THA) due to good biocompatibility, optimal mechanical properties and high load bearing capacity. However, as Ti6Al4V is not bioactive in its conventional form, hydroxyapatite (HAp) and tricalcium phosphate (TCP) have been widely used as coatings of metal prostheses due to their osteogenic properties and ability to form strong bonds with bone tissue. A promising approach consists in creating a bioactive surface metal matrix composite Ti6Al4V+β-TCP or Ti6Al4V+HAp, obtained by hot pressing (HP) of powders. In this work, the tribological performance of Ti6Al4V+β-TCP and Ti6Al4V+HAp composites is studied to evaluate the frictional response and surface damage representative of prosthesis implantation, key factors in bone fixation. Biocomposites with 10vol% β-TCP and 10vol% Hap, as well as base titanium alloy, were prepared by HP with two surface finishing conditions - polished (Ra=0.3-0.5μm) and sandblasted (Ra=2.1-2.5μm) - for tribological testing against bovine cortical bone tissue. The static friction increases with surface roughness (from 0.20 to 0.60), whereas the kinetic regime follows an inverse trend for the biocomposites. In contrast with current knowledge, this study shows that an implant design solution based on Ti6Al4V+β-TCP or Ti6Al4V+HAp biocomposites with polished surfaces results in an improved primary stability of implants, when compared to traditional rough surfaces. Moreover, it is also expected that the secondary stability will improve due to the adhesion between bone and HAp/β-TCP, increasing the overall stability of the implant., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Pure chitosan, glutaraldehyde crosslinked chitosan, and a blend of chitosan with poly(ethylene oxide) (PEO) membranes were prepared. The three membranes were characterized in terms of their swelling capacities as well as their permeabilities to a drug model (sulfamerazine sodium salt). For the permeation experiments, the variables analyzed were the type of membrane and the initial drug concentration in the liquid phase (from 0.1% to 1.5%). Permeability coefficients were calculated using UV spectroscopy. The results showed that for the three analyzed membranes, the permeability did not change with time (over the studied time interval). An increase in the permeability for CHI/PEO membranes compared to those made of pure chitosan was also observed, possibly due to microporous region formation and/or crystallinity reduction. For the crosslinked membrane, an even higher increase in the permeability coefficient was observed. In this case, the increase was attributed to free volume variation.

In this research a surfactant derived from a vegetable oil (coconut oil) was used to remove chromium from a tannery effluent. In the extraction process, a Morris extractor was used. Important variables used in assessing the optimization of the process included agitation speed, solvent rate and total flow rate. The experiments were conducted using a 2(3) factorial design. According to the response from the experimental design, the effects of each variable were calculated and the interactions between them determined. Response surface methodology was employed to study the effects of the studied variables. The optimum operational conditions were: agitation speed, 428 rpm; solvent rate, 0.37; total flow rate, 2.0 l h(-1). After extraction process, a re-extraction study was accomplished and the obtained results showed that chromium could be removed from the microemulsion phase by hydrochloric and sulphuric acidic solutions, what allows its reuse in the leather manufacturing process.

In this work, the use of microemulsion in the extraction of gallium, with Bayer process, has been studied. The studied microemulsion systems were: systems I and II, with saponified coconut oil (SCO) and 4-ethyl,1-methyl,7-octyl,8-hydroxyquinoleine (Kelex-100) as extractants. The extraction essays by microemulsion were carried out by applying an experimental planning method whose microemulsion points were prepared within an experimental domain favorable to the extraction. Gallium and aluminum extraction percentages, in each point, were evaluated via a statistical treatment of the data, with the use of variance analysis and mathematical models. In system I (SCO), percentages of extraction of 85.5% for gallium and 35.4% for aluminum were achieved; in system II (Kelex-100), the yields were 100% for gallium and 99.9% for aluminum. The reextraction study with sulfuric acid presented the same behavior for both systems, with efficiency depending upon the concentration of the acid, and allowing for a selective reextraction of gallium and aluminum.