Extracellular vesicles (EVs) have been identified as important mediators for cell-to-cell communication. Citrus-based EVs in particular offer an excellent platform for nutraceutical delivery systems, as their endemic cargo includes micronutrients (e.g., ascorbic acid), which contribute to their antioxidant capacity. Despite being extensively investigated as to their therapeutic and diagnostic potential, their cargo is inherently unstable and thus directly affected by their storage and preservation. In this study, EVs were isolated from citrus fruit using tangential flow filtration and evaluated for their physicochemical characteristics, antioxidant activity and effects on human cells. To assess how their isolation and preservation methods affect these properties, the EVs were tested immediately after isolation (from fresh and freeze-thawed juices) or following freeze-drying. A measurable biological effect of cryoprotection on citrus-derived EVs was evident, whether during or after isolation. This was more pronounced in the cell-based assays, ranging from −4% to +32% in human skin fibroblast proliferation. Nevertheless, the effects on human cancer cells varied depending on the cell line. Although these results should be considered preliminary observations, subject to further investigation, it is safe to state that any type of preservation is expected to impact the EVs’ biological activity.

Selecting a post-and-core system for endodontically treated posterior teeth remains challenging. Cast post-and-core (CPC) and fiber post with composite resin core (FPCC) systems are used to restore structurally compromised teeth. Their biomechanical interactions with the remaining tooth structure under functional loading remain poorly understood. The purpose of this finite element analysis study was to assess how CPC and FPCC restorations influence internal stresses and interfacial stress distributions in a restored mandibular first molar under functional loading. A fully dentate mandibular model (W10532; 3B Scientific GmbH) was reconstructed using microcomputed tomography (TomoScope H; Werth Inc). A mandibular first molar was restored with a CPC or an FPCC, each supporting a complete coverage monolithic lithium disilicate crown. Finite element analysis simulated occlusal loading during masticatory function using physiologic loading vectors and validated boundary conditions. Anatomically accurate geometries and anisotropic material definitions were incorporated. The models were meshed with a converged finite element grid (<0.2%). Maximum principal stress was evaluated in enamel, dentin, bone, and periodontal ligament, while von Mises stress quantified internal post-and-core behavior. Stress and strain distributions were compared among restorations, with emphasis on internal post stresses and interfacial tensile stresses at the crown-core-post junction. The CPC model exhibited a 234% increase in internal post stresses compared to the FPCC model. Dentin stress levels remained similar between the systems, varying by about 4%. The FPCC model demonstrated a 15.2% increase in tensile stress at the crown-core-post interface and a 63.8% increase along the apical crown margin. These elevated interfacial stresses coincided with micromovement at bonded interfaces. Based on the findings of this finite element analysis study, CPC restorations concentrate higher internal stresses. In contrast, FPCC restorations reduce internal post stress but increase interfacial tensile stresses. Dentin stresses remained consistent across systems, indicating that the main difference is in failure mode.