Additive manufacturing represents a powerful tool for the fabrication of parts with complex shapes by the deposition and the consolidation of materials as opposed to subtractive manufacturing methodology. Selective laser sintering (SLS), one of the most popular powder bed fusion (PBF) technologies for thermoplastic part production, has demonstrated extensive applications in various industrial sectors. The process involves the deposition of homogeneous powder layers and employs a laser source to selectively melt a powder bed according to a CAD model. Due to its layer-by-layer nature, voids and pores are inevitably introduced in the fabricated thermoplastic parts. Porosity represents one of the major limitations of this technology being one of the main causes of the variation of the mechanical properties. With the intention of providing support for reducing the porosity and thus increasing the quality and performance of the final product, in this paper, a brief review was carried out focusing on the SLS process parameters and their interaction with the porosity of the product. In addition, an in-depth look was given to the mechanisms of formation and consolidation of pores within parts made of polymeric material.

For different manufacturing processes, porosity occurs in parts made using selective laser sintering (SLS) technology, representing one of the weakest points of materials produced with these processes. Even though there are different studies involving many polymeric materials employed via SLS, and different manuscripts in the literature that discuss the porosity occurrence in pure or blended polymers, to date, no researcher has reported a systematic and exhaustive comparison of the porosity percentage. A direct comparison of the available data may prove pivotal in advancing our understanding within the field of additively manufactured polymers. This work aims to collect and compare the results obtained by researchers who have studied SLS’s applicability to different amorphous or semi-crystalline polymers and pure or blended materials. In particular, the porosity values obtained by different researchers are compared, and tables are provided that show, for each material, the process parameters and the measured porosity values.

The rapid advancement of materials science has revolutionized total hip arthroplasty (THA), a critical orthopedic procedure aimed at restoring mobility and improving patient quality of life. This review investigates the evolution of biomaterials used in THA, analyzing their mechanical, biological, and chemical properties. The study outlines the transition from early natural materials to modern metals, polymers, and ceramics, highlighting their benefits and limitations in clinical applications. Particular emphasis is placed on the development of advanced materials such as highly cross-linked polyethylene (HXLPE), zirconia-toughened alumina (ZTA), and tantalum alloys (Ta), which demonstrate enhanced biocompatibility, wear resistance, and longevity. By examining emerging trends, including bioactive coatings and nanotechnology, this paper aims to provide a comprehensive understanding of current challenges and future directions in material selection for hip prostheses, ultimately aiming to minimize annual revision rates and improve long-term outcomes.