Detection properties of indium-111 and IRDye800CW for intraoperative molecular imaging use across tissue phantom models.

Significance: Intraoperative molecular imaging (IMI) enables the detection and visualization of cancer tissue using targeted radioactive or fluorescent tracers. While IMI research has rapidly expanded, including the recent Food and Drug Administration approval of a targeted fluorophore, the limits of detection have not been well-defined. Aim: The ability of widely available handheld intraoperative tools (Neoprobe and SPY-PHI) to measure gamma decay and fluorescence intensity from IMI tracers was assessed while varying characteristics of both the signal source and the intervening tissue or gelatin phantoms. Approach: Gamma decay signal and fluorescence from tracer-bearing tumors (TBTs) and modifiable tumor-like inclusions (TLIs) were measured through increasing thicknesses of porcine tissue and gelatin in custom 3D-printed molds. TBTs buried beneath porcine tissue were used to simulate IMI-guided tumor resection. Results: Gamma decay from TBTs and TLIs was detected through significantly thicker tissue and gelatin than fluorescence, with at least 5% of the maximum signal observed through up to 5 and 0.5 cm, respectively, depending on the overlying tissue type or gelatin. Conclusions: We developed novel systems that can be fine-tuned to simulate variable tumor characteristics and tissue environments. These were used to evaluate the detection of fluorescent and gamma signals from IMI tracers and simulate IMI surgery.

4D-printed shape-programmable [H+]-responsive needles for determination of urea.

Four-dimensional printing (4DP) technologies are revolutionizing the fabrication, functionality, and applicability of stimuli-responsive analytical devices. More practically, 4DP technologies are effective in fabricating devices with complex geometric designs and functions, and the degree of shape programming of 4D-printed stimuli-responsive devices can be optimized to become a reliable analytical strategy. Although shape-programming modes play a critical role in determining the analytical characteristics of 4D-printed stimuli-responsive sensing devices, the effect of shape-programming modes on the analytical performance of 4D-printed stimuli-responsive devices remains an unexplored subject. We employed digital light processing three-dimensional printing (3DP) with acrylate-based photocurable resins and 2-carboxyethyl acrylate (CEA)-incorporated photocurable resins for 4DP of the bending, helixing, and twisting needles. Upon immersion in samples with pH values above the pKa of CEA, the electrostatic repulsion among the dissociated carboxyl groups of polyCEA caused swelling of the CEA-incorporated part and [H+]-dependent shape programming. When coupling with the derivatization reaction of the urease-mediated hydrolysis of urea, the decline in [H+] induced shape programming of the needles, offering reliable determination of urea based on the shape-programming angles. After optimizing the experimental conditions, the helixing needles provided the best analytical performance, with the method's detection limit of 0.9 µM. The reliability of this analytical method was validated by determining urea in samples of human urine and sweat, fetal bovine serum, and rat plasma with spike analyses and comparing these results with those obtained from a commercial assay kit. Our demonstration and analytical results suggest the importance of optimizing the shape-programming modes to improve the analytical performance of 4D-printed stimuli-responsive shape-programming sensing devices and emphasize the benefits and applicability of 4DP technologies in advancing the development and fabrication of stimuli-responsive sensing devices for chemical sensing and quantitative chemical analyses.

Factors Influencing the Fit and Retention of Computer-aided Design/Computer-aided Manufacturing-based Three-dimensional Printed Band and Loop Space Maintainers.

Three-dimensional (3D) scanning and printing in the field of pediatric dentistry is an augmented reality that has several clinical implications and advantages. The aim of this current short communication and technical note is to discuss the possibility of various shortcomings of the current intraoral scanning and 3D printing and the various limitations a clinician can face. How to cite this article: Tirupathi S, Rathi N. Factors Influencing the Fit and Retention of Computer-aided Design/Computer-aided Manufacturing-based Three-dimensional Printed Band and Loop Space Maintainers. Int J Clin Pediatr Dent 2024;17(6):734-735.

Feasibility of Easy to Use and Inexpensive Three-Dimensional Printed Educational Model of Temporal Bone: Practiced Without Drilling.

OBJECTIVE: Three-dimensional (3D) printed temporal bone model draws great attention as a promising alternative for conventional cadaveric model in education of otologic surgery. However, its high price and requirement for specialized tools hinder widespread use. We devised a simple educational model based on lattice structure to overcome these problems and compared it with a commercial model. METHODS: We converted high-resolution temporal bone computed tomography images into stereolithography format, and printed it using the G005 3D printing system from CUBICON©. In this process, the part to be drilled out was made of lattice structure. We evaluated the model by a questionnaire prepared in advance, and compared the results with those of a commercial model. RESULTS: We created an educational 3D printed temporal bone lattice model one-tenth the cost of commercial temporal bone. Our model reproduced the important structures of the temporal bone, produced less dust, and had similar strength and grinding sensation compared to the commercial model. The surface texture and reproducibility were comparable to the commercial model. Although most of structures were remodeled more elaborately in the commercial model than our model, our model demonstrated significant potential as a cost-effective educational tool for medical students and residents. CONCLUSION: 3D printed temporal bone lattice model has potential for widespread use due to low cost and easy accessibility. Further improvements in the fine structures of the temporal bone are necessary to enhance its utility as an educational model.

3D-printed orthoses and prostheses for people with physical disability in rehabilitation centers: a scoping review.

AIMS: The World Health Organization points out that, by 2030, two billion people will need at least one assistive product. 3D printing can be used to meet the demands when dispensing these products. PURPOSE: This review aims to map the use of 3D printing in the manufacture of orthoses and prostheses for people with physical disability at rehabilitation centers. METHODS: Publications that deal with the use of 3D printing for the manufacture of orthoses and prostheses were used, preferably studies from 2012 to 2022. RESULTS: The majority of studies, 56.25%, were quantitative and 46.25% were evaluative research. None of the studies were characterized as developed at rehabilitation centers. 75% of them had the participation of people with physical disability. The use of 3D printing was, for the most part, for the development of assistive technologies for the upper limbs at 56.25%, while 31.25% were for the lower limbs. CONCLUSION: The assistive products developed were orthoses and prostheses for the wrist, hands, fingers, upper limbs, writing devices, sockets, knees, and feet. Although there were positive results in their performance, some limitations related to strength, stiffness, and resistance were observed.

3D printed polylactic acid/polyethylene glycol/bredigite nanocomposite scaffold enhances bone tissue regeneration via promoting osteogenesis and angiogenesis.

Recently, the fabrication of personalized scaffolds with high accuracy has been developed through 3D printing technology. In the current study, polylactic acid/polyethylene glycol (PLA/PEG) composite scaffolds with varied weight percentages (0, 5, 10, 20 and 30 %) of bredigite nanoparticles (B) were fabricated using the 3D printing and then characterized through scanning electron microscopy and Fourier transform infra-red spectroscopy. The addition of B nanoparticles up to 20 wt% to PLA/PEG scaffold increased the compressive strength (from 7.59 to 13.84 MPa) and elastic modulus (from 142.42 to 268.33 MPa). The apatite formation ability as well as inorganic ion release in simulated body fluid were investigated for 28 days. The MG-63 cells viability and adhesion were enhanced by increasing the amount of B in the PLA/PEG scaffold and the osteogenic differentiation of the rat bone marrow mesenchymal stem cells was confirmed by alkaline phosphatase activity test and alizarin red staining. According to chorioallantoic membrane assay, the highest angiogenesis occurred around the PLA/PEG/B30 scaffold. In vivo experiments on a rat calvarial defect model demonstrated an almost complete recovery in the PLA/PEG/B30 group within 8 weeks. Based on the results, the PLA/PEG/B30 composite scaffold is proposed as an optimal scaffold to repair bone defects.

Use of 3D-printed model to plan the surgical management of a patient with isolated orbital floor fracture: a case report.

Background: Orbital floor fractures typically manifest as eyeball mobility disorders with double vision (diplopia), enophthalmia, and infraorbital paresis. Surgical treatment of these fractures involves orbital floor reconstruction. The procedure involves freeing the trapped tissues from the lumen of the maxillary sinus and rebuilding the orbital floor. Technological progress in the field of three-dimensional (3D) printing allows physical prototyping of the implants to be used during the procedure. Case Description: A 43-year-old female patient presented to the hospital with diplopia, which first occurred after a fall from own height. Examinations, including a computed tomography (CT) confirmed the diagnosis of an orbital floor fracture. 3D printing was used to plan the surgical treatment of the patient. Based on preoperative CT, a 1:1 scale model was prepared by means of 3D printing to demonstrate the fractured orbital area. It was later used to pre-cut a Codubix prosthesis, which was subsequently used to reconstruct the fractured bone. The patient's postoperative course was uneventful. Instant improvement in diplopia was noted. A CT scan was performed on the 3rd day after surgery. No herniation into the maxillary sinus was observed. Conclusions: 3D printing seems to be a useful method that allows more thorough preparation for the surgery and also could potentially shorten its duration.

Biomimetic scaffold and 3D bioprinting in dental application: A review.

Biomimetic scaffold and 3D bioprinting technologies have emerged as promising avenues in tissue engineering and regenerative medicine, offering innovative approaches to address the limitations of conventional tissue engineering methods. This review article provides a comprehensive overview of recent advancements, challenges, and future prospects in the field of biomimetic scaffold fabrication and 3D bioprinting techniques.

Three-dimensional Printing in Spinal Surgery.

OBJECTIVES: Carry out an update and systematic review on the use of three-dimensional printing (3DP) in spinal surgery. METHODS: A systematic literature review was performed using the PubMed database in March 2024. "Spine surgery" and "3d printing" were the search terms. Only articles published from 2014 to 2024 and clinical trails were selected for inclusion. Non-English or Spanish articles were excluded. This review complied with the Preferred Reported Items for Systematic Reviews and Meta-Analysis (PRISMA) guideline. RESULTS: Ten articles were included after screening and evaluation. The majority of the studied diseases were deformities (n = 3) and traumas (n = 3), followed by degenerative diseases (n = 2). Two articles dealt with surgical techniques. Six articles studied the creation of personalized guides for inserting screws; two were about education, one related to educating patients about their disease and the other to teaching residents surgical techniques; two other articles addressed surgical planning, where biomodels were printed to study anatomy and surgical programming. CONCLUSIONS: 3D printing is one of the most-used tools in spine surgeries, but there are still randomized articles available on the subject. Using this technology seems to have a positive effect on patient education regarding their disease and surgical planning.

Accuracy and clinical fit of milled versus rapid prototyped orthognathic surgical splints.

Three-dimensional (3D) printing has become an integral part of orthognathic surgery. However, there is a lack of studies evaluating accuracy of orthognathic surgical splints fabricated from subtractive milling versus additive 3D printing. The primary aim of this in-vitro study was to compare the differences in trueness between milled and 3D-printed splints, while the secondary aim was to compare the differences in clinical fit of these splints. A sample of eight patients was selected, and STL files of the final orthognathic surgical splint were used to fabricate three splints for each of the eight cases. The first splint was fabricated by subtractive milling (SM), whereas the second and third splints were 3D printed with Digital Light Processing (DLP) and Laser Stereolithography (SLA), respectively. Paired superimposition of scans was performed using a reference model. The clinical fit of the splints to the printed models was also assessed. The mean root mean square (RMS) deviations for the SM, SLA, and DLP were 0.11 ± 0.02, 0.16 ± 0.02 and 0.14 ± 0.02 respectively. The post-hoc analysis showed that the SM splints had the highest accuracy (p < 0.01). However, DLP splints showed the best clinical fit, followed by SM and SLA. In conclusion, splints fabricated by SM were more accurate than those fabricated by 3D printing, although this difference may not be clinically significant. The site, rather than the magnitude of the errors, may have a greater effect on the clinical usability of splints. In general, SM and DLP splints demonstrated a good clinical fit and were suitable for the fabrication of surgical splints.

Multimodal image-guided surgical robot versus 3D-printed template for brachytherapy of malignant tumours in the skull base and deep facial region: a clinical comparative study.

This study compared a multimodal image-guided robot and three-dimensionally (3D) printed templates for implanting iodine-125 (I125) radioactive seeds in patients with malignant tumours in the skull base and deep facial region. Seventeen patients who underwent I125 radioactive seed implantation between December 2018 and December 2019 were included. The operation time, intraoperative blood loss, and accuracy of seed implantation were compared between the multimodal image-guided robot-assisted implantation (experimental) group (n = 7) and 3D-printed template-assisted implantation (control) group (n = 10). In total, 291 seeds were implanted in the experimental group and 436 in the control group; the mean error of seed implantation accuracy was 1.95 ± 0.13 mm and 1.90 ± 0.08 mm, respectively (P = 0.309). The preparation time was 26.13 ± 5.28 min in the experimental group and 0 min in the control group, while the average operation time was 34.44 ± 6.39 min versus 43.70 ± 6.06 min, respectively. The intraoperative blood loss was 4.96 ± 1.76 ml (experimental) versus 8.97 ± 2.99 ml (control) (P = 0.123). Multimodal image-guided robot-assisted I125 radioactive seed implantation met the clinical requirements for treating malignant tumours in the skull base and deep facial regions.

Process Development for Fabricating 3D-Printed Polycaprolactone-Infiltrated Hydroxyapatite Bone Graft Granules: Effects of Infiltrated Solution Concentration and Agitating Liquid.

Bone grafts are commonly used in orthopedic and dental surgeries to facilitate bone repair and regeneration. A new type of bone graft, polycaprolactone-infiltrated three dimensionally printed hydroxyapatite (3DP HA/PCL), was previously developed by infiltrating polycaprolactone (PCL) into preformed three-dimensional-printed hydroxyapatite (3DP HA) that was fabricated using binder jetting technology combined with a low-temperature phase transformation process. However, when producing small granules, which are often used for bone grafting, issues of granule agglomeration emerged, complicating the application of this method. This study aimed to develop a fabrication process for 3DP HA/PCL bone graft granules using solution infiltration and liquid agitation. The effects of varying PCL solution concentrations (40% and 50% w/w) and different agitating liquids (deionized water or DI, N-Methyl-2-Pyrrolidone or NMP, and an NMP-DI mixture) on the properties of the resulting composites were investigated. XRD and FTIR analysis confirmed the coexistence of HA and PCL within the composites. The final PCL content was comparable across all conditions. The contact angles of 3DP HA/PCL were 26.3 and 69.8 degree for 40% and 50% PCL solution, respectively, when using DI, but were zero when using NMP and NMP-DI. The highest compression load resistance and diametral tensile strength were achieved using the 50% PCL solution with DI or the NMP-DI mixture. DI resulted in a dense PCL coating, while NMP and the NMP-DI mixture produced a porous and irregular surface morphology. All samples exhibited a porous internal microstructure due to PCL infiltration into the initial pores of the 3D-printed HA. Biocompatibility tests showed that all samples supported the proliferation of MC3T3-E1 cells, with the greatest OD values observed for the 50% PCL solution with DI or the NMP-DI mixture at each cultured period. Considering the microstructural, mechanical, and biological properties, the 50% PCL solution with the NMP-DI mixture demonstrated overall desirable properties.

Interpretable Machine Learning-Based Influence Factor Identification for 3D Printing Process-Structure Linkages.

Three-dimensional printing technology is a rapid prototyping technology that has been widely used in manufacturing. However, the printing parameters in the 3D printing process have an important impact on the printing effect, so these parameters need to be optimized to obtain the best printing effect. In order to further understand the impact of 3D printing parameters on the printing effect, make theoretical explanations from the dimensions of mathematical models, and clarify the rationality of certain important parameters in previous experience, the purpose of this study is to predict the impact of 3D printing parameters on the printing effect by using machine learning methods. Specifically, we used four machine learning algorithms: SVR (support vector regression): A regression method that uses the principle of structural risk minimization to find a hyperplane in a high-dimensional space that best fits the data, with the goal of minimizing the generalization error bound. Random forest: An ensemble learning method that constructs a multitude of decision trees and outputs the class that is the mode of the classes (classification) or mean prediction (regression) of the individual trees. GBDT (gradient boosting decision tree): An iterative ensemble technique that combines multiple weak prediction models (decision trees) into a strong one by sequentially minimizing the loss function. Each subsequent tree is built to correct the errors of the previous tree. XGB (extreme gradient boosting): An optimized and efficient implementation of gradient boosting that incorporates various techniques to improve the performance of gradient boosting frameworks, such as regularization and sparsity-aware splitting algorithms. The influence of the print parameters on the results under the feature importance and SHAP (Shapley additive explanation) values is compared to determine which parameters have the greatest impact on the print effect. We also used feature importance and SHAP values to compare the importance impact of print parameters on results. In the experiment, we used a dataset with multiple parameters and divided it into a training set and a test set. Through Bayesian optimization and grid search, we determined the best hyperparameters for each algorithm and used the best model to make predictions for the test set. We compare the predictive performance of each model and confirm that the extrusion expansion ratio, elastic modulus, and elongation at break have the greatest influence on the printing effect, which is consistent with the experience. In future, we will continue to delve into methods for optimizing 3D printing parameters and explore how interpretive machine learning can be applied to the 3D printing process to achieve more efficient and reliable printing results.

3D-printed thermally expanded monolithic foam for solid-phase extraction of multiple trace metals.

Digital light processing (DLP) 3DP, commercial acrylate-based photocurable resins, and thermally expandable microspheres-incorporated flexible photocurable resins were employed to fabricate an SPE column with a thermally expanded monolithic foam for extracting Mn, Co, Ni, Cu, Zn, Cd, and Pb ions prior to the determination using inductively coupled plasma mass spectrometry. After optimization of the thermally activated foaming, the design and fabrication of the SPE column, and the automatic analytical system, the DLP 3D-printed SPE column with the thermally expanded monolithic foam extracted the metal ions with up to 14.8-fold enhancement (relative to that without incorporating the microspheres), with absolute extraction efficiencies all higher than 95.6%, and method detection limits in the range from 0.5 to 5.2 ng L-1. We validated the reliability and applicability of this method by determination of the metal ions in several reference materials (CASS-4, SLRS-5, 1643f, and Seronorm Trace Elements Urine L-2) and spiked seawater, river water, ground water, and human urine samples. The results illustrated that to incorporate the thermally expandable microspheres into the photocurable resins with a post-printing heating treatment enabled the DLP 3D-printed thermally expanded monolithic foam to substantially improve the extraction of the metal ions, thereby extending the applicability of SPE devices fabricated by vat photopolymerization 3DP techniques.

Development of fetal magnetic resonance imaging (MRI) phantom.

Background: Anthropomorphic phantoms play an important role in routine clinical practice. They can be used to calibrate magnetic resonance imaging (MRI) scanners, control the diagnostic equipment quality, and reduce the acquisition time. The latter is especially critical for diagnosing fetal anomalies, which requires optimal image quality within the shortest possible time. This paper aims to develop an MRI fetal phantom and determine the materials that best mimic the magnetic resonance (MR) characteristics of its internal organs. Future phantom features will include simulations of fetal limb movements. Methods: A single MRI study of a pregnant woman at 20 weeks 3 days of gestation was used as a reference and for image segmentation. Anonymized Digital Imaging and Communication in Medicine (DICOM) files were imported into 3D Slicer v. 5.2.1 for segmentation of the uterus, fetus, and internal organs. Based on the performed segmentation, a three-dimensional model was obtained for printing on a 3D printer. The mold was 3D printed on an Anycubic Photon M3 Max printer. The paper showcases the selection and manufacturing of compositions to simulate the relaxation times of the fetal organs. Formulations for emulsions and carrageenan- and agar-based hydrogels are presented. The selected compositions were used to fill the 3D printed model. Results: Statistical analysis showed no significant differences in absolute and relative signal values obtained from scans of a pregnant woman at 20 weeks and 3 days and a fetal phantom. Conclusions: During the study, an anthropomorphic fetal phantom was constructed, filled with compositions with relaxation times T1 and T2 similar to the control values of the corresponding tissues. The phantom can be used to set up and optimize fetal MRI protocols, train and educate medical students, residents, graduate students, and X-ray technicians, as well as to timely control image quality and equipment serviceability.

The Bony Nasal Cavity and Paranasal Sinuses of Big Felids and Domestic Cat: A Study Using Anatomical Techniques, Computed Tomographic Images Reconstructed in Maximum-Intensity Projection, Volume Rendering and 3D Printing Models.

This study aims to develop three-dimensional printing models of the bony nasal cavity and paranasal sinuses of big and domestic cats using reconstructed computed tomographic images. This work included an exhaustive study of the osseous nasal anatomy of the domestic cat carried out through dissections, bone trepanations and sectional anatomy. With the use of OsiriX viewer, the DICOM images were postprocessed to obtaining maximum-intensity projection and volume-rendering reconstructions, which allowed for the visualization of the nasal cavity structures and the paranasal sinuses, providing an improvement in the future anatomical studies and diagnosis of pathologies. DICOM images were also processed with AMIRA software to obtain three-dimensional images using semiautomatic segmentation application. These images were then exported using 3D Slicer software for three-dimensional printing. Molds were printed with the Stratasys 3D printer. In human medicine, three-dimensional printing is already of great importance in the clinical field; however, it has not yet been implemented in veterinary medicine and is a technique that will, in the future, in addition to facilitating the anatomical study and diagnosis of diseases, allow for the development of implants that will improve the treatment of pathologies and the survival of big felids.

Systematization of Steps for Printing 3D Models of Orthopedic Deformities.

As in many areas of knowledge, rapid prototyping technology or additive manufacturing, popularly known as three-dimensional (3D) printing, has been gaining ground in medicine in recent years, with different applications. Numerous are the benefits of this science in orthopedic surgery, by allowing the conversion of imaging tests into 3D models. Therefore, the aim of the present study is to describe a practical step-by-step for the printing of parts from patient imaging. This is a methodological study, considering preoperative computed tomography (CT) scans of patients with orthopedic deformities. Initially, the digital imaging and communications in medicine (DICOM) examination should be imported into the 3D reconstruction software of anatomical structures for the segmentation and conversion process to the stereolithography (STL) format. The next step is to import the STL file into the 3D modeling software, which allows you to work freely by manipulating the 3D mesh. The 3D models were printed additively on the GTMax3D Core A3v2 fused deposition modeling (FDM) technology printer.

Personalized Biomodel of the Cervical Spine for Laboratory Laminoplasty Training.

OBJECTIVE: The use of biomodels in the laboratory for studying and training cervical laminoplasty has not yet been reported. We propose the use of a cervical spine biomodel for surgical laminoplasty training. METHODS: This is an experimental study. Ten 3D identical cervical spine biomodels were printed based on computed tomography (CT) and magnetic resonance imaging scans of a patient diagnosed with spondylotic cervical myelopathy. The additive manufacturing method used fused deposition modeling and polylactic acid (PLA) was selected as the raw material. The sample was divided into 2 groups: control (n = 5; the biomodels were submitted to CT scanning) and open-door (n = 5; the biomodels were submitted to open-door laminoplasty and postoperative CT). The area and anteroposterior diameter of the vertebral canal were measured on CT scans. RESULTS: Printing each piece took 12 hours. During the surgical procedure, there was sufficient support from the biomodels to keep them immobilized. Using the drill was feasible; however continuous irrigation was mandatory to prevent plastic material overheating. The raw material made the biomodel CT study possible. The vertebral canal dimensions increased 24.80% (0.62 cm2) in area and 24.88% (3.12 mm) in anteroposterior diameter CONCLUSIONS: The cervical spine biomodels can be used for laminoplasty training, even by using thermosensitive material such as PLA. The use of continuous irrigation is essential while drilling.

Guided versus non-guided chin repositioning: a retrospective study on accuracy.

Genioplasty is a widely used surgical approach to address chin deformities by performing an osteotomy on the inferior border of the mandible to allow for comprehensive repositioning of the chin. This study aimed to compare the accuracy of freehand chin repositioning with a guided technique that employed specialised surgical guides. For this retrospective study, data from 30 adult patients who underwent orthognathic surgery to correct dentofacial deformities were analysed. All patients underwent virtual planning before surgery, with half of them treated using freehand chin repositioning and the other half using the guided technique. The surgical outcomes were measured and compared with the virtual plan to assess the positional and rotational accuracy of the techniques. In terms of translational assessment, noteworthy values that exceeded clinically acceptable limits were observed only in sagittal movement in the freehand group (0.97 mm, interquartile range (IQR) 0.73-2.29 mm). Regarding rotational accuracy, both groups exhibited an IQR that surpassed acceptable limits for pitch (3.26°, IQR 2.06-5.20 for the guided group and 2.57°, IQR 1.63-4.24° for the freehand group). The Mann-Whitney test indicated no statistical differences between the groups in any translational or rotational assessment. In conclusion, although there was no statistical difference, the guided technique proved effective in achieving clinically acceptable accuracy in all positions and almost all rotations, displaying superior results in sagittal positioning compared with the freehand technique. To fully harness the advantages of guides and to guarantee accuracy in all rotations, we recommend further research involving guides made of more rigid materials, and customised implants.