Method of designing and manufacturing craniofacial soft tissue prostheses using Additive Manufacturing: A case study

A statistical shape model for estimating missing soft tissues of the face in a black South African population

PURPOSE

Facial disfigurement may affect the quality of life of many patients. Facial prostheses are often used as an adjuvant to surgical intervention and may sometimes be the only viable treatment option. Traditional methods for designing soft-tissue facial prostheses are time-consuming and subjective, while existing digital techniques are based on mirroring of contralateral features of the patient, or the use of existing feature templates/models that may not be readily available. We aim to support the objective and semi-automated design of facial prostheses with primary application to midline or bilateral defect restoration where no contralateral features are present. Specifically, we developed and validated a statistical shape model (SSM) for estimating the shape of missing facial soft tissue segments, from any intact parts of the face.

MATERIALS AND METHODS

An SSM of 3D facial variations was built from meshes extracted from computed tomography and cone beam computed tomography images of a black South African sample (n = 235) without facial disfigurement. Various types of facial defects were simulated, and the missing parts were estimated automatically by a weighted fit of each mesh to the SSM. The estimated regions were compared to the original regions using color maps and root-mean-square (RMS) distances.

RESULTS

Root mean square errors (RMSE) for defect estimations of one orbit, partial nose, cheek, and lip were all below 1.71 mm. Errors for the full nose, bi-orbital defects, as well as small and large composite defects were between 2.10 and 2.58 mm. Statistically significant associations of age and type of defect with RMSE were observed, but not with sex or imaging modality.

CONCLUSION

This method can support the objective and semi-automated design of facial prostheses, specifically for defects in the midline, crossing the midline or bilateral defects, by facilitating time-consuming and skill-dependent aspects of prosthesis design.

Future trends of additive manufacturing in medical applications: An overview

Additive Manufacturing (AM) has recently demonstrated significant medical progress. Due to advancements in materials and methodologies, various processes have been developed to cater to the medical sector's requirements, including bioprinting and 4D, 5D, and 6D printing. However, only a few studies have captured these emerging trends and their medical applications. Therefore, this overview presents an analysis of the advancements and achievements obtained in AM for the medical industry, focusing on the principal trends identified in the annual report of AM3DP.

Progress in Photocurable 3D Printing of Photosensitive Polyurethane: A Review

In recent years, as a class of advanced additive manufacturing (AM) technology, photocurable 3D printing has gained increasing attention. Based on its outstanding printing efficiency and molding accuracy, it is employed in various fields, such as industrial manufacturing, biomedical, soft robotics, electronic sensors. Photocurable 3D printing is a molding technology based on the principle of area-selective curing of photopolymerization reaction. At present, the main printing material suitable for this technology is the photosensitive resin, a composite mixture consisting of a photosensitive prepolymer, reactive monomer, photoinitiator, and other additives. As the technique research deepens and its application gets more developed, the design of printing materials suitable for different applications is becoming the hotspot. Specifically, these materials not only can be photocured but also have excellent properties, such as elasticity, tear resistance, fatigue resistance. Photosensitive polyurethanes can endow photocured resin with desirable performance due to their unique molecular structure including the inherent alternating soft and hard segments, and microphase separation. For this reason, this review summarizes and comments on the research and application progress of photocurable 3D printing of photosensitive polyurethanes, analyzing the advantages and shortcomings of this technology, also offering an outlook on this rapid development direction.

Additive manufacturing of sustainable biomaterials for biomedical applications

Biopolymers are promising environmentally benign materials applicable in multifarious applications. They are especially favorable in implantable biomedical devices thanks to their excellent unique properties, including bioactivity, renewability, bioresorbability, biocompatibility, biodegradability and hydrophilicity. Additive manufacturing (AM) is a flexible and intricate manufacturing technology, which is widely used to fabricate biopolymer-based customized products and structures for advanced healthcare systems. Three-dimensional (3D) printing of these sustainable materials is applied in functional clinical settings including wound dressing, drug delivery systems, medical implants and tissue engineering. The present review highlights recent advancements in different types of biopolymers, such as proteins and polysaccharides, which are employed to develop different biomedical products by using extrusion, vat polymerization, laser and inkjet 3D printing techniques in addition to normal bioprinting and four-dimensional (4D) bioprinting techniques. This review also incorporates the influence of nanoparticles on the biological and mechanical performances of 3D-printed tissue scaffolds. This work also addresses current challenges as well as future developments of environmentally friendly polymeric materials manufactured through the AM techniques. Ideally, there is a need for more focused research on the adequate blending of these biodegradable biopolymers for achieving useful results in targeted biomedical areas. We envision that biopolymer-based 3D-printed composites have the potential to revolutionize the biomedical sector in the near future.

Capturing patient anatomy for designing and manufacturing personalized prostheses

Prostheses play a critical role in healthcare provision for many patients and encompass aesthetic facial prostheses, prosthetic limbs and prosthetic joints, bones, and other implantable medical devices in musculoskeletal surgery. An increasingly important component in cutting-edge healthcare treatments is the ability to accurately capture patient anatomy in order to guide the manufacture of personalized prostheses. This article examines methods for capturing patient anatomy and discusses the degrees of personalization in medical manufacturing alongside a summary of current trends in scanning technology with a focus on identifying workflows for incorporating personalization into patient-specific products. Over the next decade, with increased harmonization of both personalization and automated prosthetic manufacturing will be the realization of improved patient compliance, satisfaction, and clinical outcomes.