Her-Hsiung Huang

Polyetherketoneketone (PEKK) exhibits satisfactory mechanical properties and biocompatibility, with an elastic modulus closely resembling that of natural bone. This property reduces the stress-shielding effect associated with bone implants. However, the biological inertness of the PEKK surface remains a significant limitation for its application in bone tissue engineering. The objective of this study was to create a superhydrophilic 3D porous structure on the surface of PEKK to enhance biocompatibility, in terms of vascularization and bone remodeling. A combination of mechanical, chemical, and physical surface treatments was employed to modify the PEKK surface. Initially, mechanical sandblasting was used to create a rough surface to promote mechanical interlocking with bone tissue. Subsequently, chemical acid etching and physical low-temperature atmospheric plasma cleaning were applied to develop a superhydrophilic 3D porous surface. The modified surfaces were characterized for morphology, roughness, hydrophilicity, and functional groups. Cellular responses, including vascularization and bone remodeling, were evaluated to assess the potential for improved biocompatibility. The combination of acid etching and low-temperature atmospheric plasma cleaning, with or without prior sandblasting, successfully created a superhydrophilic 3D porous structure on the PEKK surface. This modified surface enhanced the tube formation in human umbilical vein endothelial cells. It also promoted the adhesion and mineralization of human bone marrow mesenchymal stem cells and slightly reduced tartrate-resistant acid phosphatase expression and F-actin ring size in mouse macrophage cells. This study introduces an innovative and effective surface modification strategy for PEKK surface, combining mechanical, chemical, and physical treatments to enhance biocompatibility. The modified PEKK surface promotes angiogenic and osteogenic responses while slightly inhibiting osteoclastic activity, making it a potential alternative for dental and orthopedic PEKK implant applications.

Usually, most studies focus on toxic gas and photosensors by using electrospinning and metal oxide polycrystalline SnO₂ nanofibers (PNFs), while fewer studies discuss cell-material interactions and photoelectric effect. In this work, the controllable surface morphology and oxygen defect (V_O) structure properties were provided to show the opportunity of metal oxide PNFs to convert photoenergy into bio-energy for bio-material applications. Using the photobiomodulation effect of defect-rich polycrystalline SnO₂ nanofibers (PNFs) is the main idea to modulate the cell-material interactions, such as adhesion, growth direction, and reactive oxygen species (ROS) density. The V_O structures, including out-of-plane oxygen defects (op-V_O), bridge oxygen defects (b-V_O), and in-plane oxygen defects (ip-V_O), were studied using synchrotron analysis to investigate the electron transfer between the V_O structures and conduction bands. These intragrain V_O structures can be treated as generation-recombination centers, which can convert various photoenergies (365-520 nm) into different current levels that form distinct surface potential levels; this is referred to as the photoelectric effect. PNF conductivity was enhanced 53.6-fold by enlarging the grain size (410 nm²) by increasing the annealing temperature, which can improve the photoelectric effect. In vitro removal of reactive oxygen species (ROS) can be achieved by using the photoelectric effect of PNFs. Also, the viability and shape of human bone marrow mesenchymal stem cells (hMSCs-BM) were also influenced significantly by the photobiomodulation effect. The cell damage and survival rate can be prevented and enhanced by using PNFs; metal oxide nanofibers are no longer only environmental sensors but can also be a bio-material to convert the photoenergy into bio-energy for biomedical science applications.

Polyetheretherketone (PEEK) is an emerging thermoplastic polymer with good mechanical properties and an elastic modulus similar to that of alveolar bone. PEEK dental prostheses for computer-aided design/computer-aided manufacturing (CAD/CAM) systems on the market often have additives of titanium dioxide (TiO₂) to strengthen their mechanical properties. However, the effects of combining aging, simulating a long-term intraoral environment, and TiO₂ content on the fracture characteristics of PEEK dental prostheses have rarely been investigated. In this study, two types of commercially available PEEK blocks, containing 20% and 30% TiO₂, were used to fabricate dental crowns by CAD/CAM systems and were aged for 5 and 10 h based on the ISO 13356 specifications. The compressive fracture load values of PEEK dental crowns were measured using a universal test machine. The morphology and crystallinity of the fracture surface were analyzed by scanning electron microscopy and an X-ray diffractometer, respectively. Statistical analysis was performed using the paired t-test (α = 0.05). Results showed no significant difference in the fracture load value of the test PEEK crowns with 20% and 30% TiO₂ after 5 or 10 h of aging treatment; all test PEEK crowns have satisfactory fracture properties for clinical applications. Fracture surface analysis revealed that all test crowns fractured from the lingual side of the occlusal surface, with the fracture extending along the lingual sulcus to the lingual edge, showing a feather shape at the middle part of the fracture extension path and a coral shape at the end of the fracture. Crystalline analysis showed that PEEK crowns, regardless of aging time and TiO₂ content, remained predominantly PEEK matrix and rutile phase TiO₂. We would conclude that adding 20% or 30% TiO₂ to PEEK crowns may have been sufficient to improve the fracture properties of PEEK crowns after 5 or 10 h of aging. Aging times below 10 h may still be safe for reducing the fracture properties of TiO₂-containing PEEK crowns.

Although polyetheretherketone (PEEK) is becoming more widely used in dentistry applications, little is known about how aging will affect this material. Therefore, this study aimed to investigate the influence of an aging treatment on fracture characteristics of PEEK dental crowns. Additionally, the impact of the addition of titanium dioxide (TiO₂) into PEEK was examined. Two types of commercial PEEK discs were used in this study, including TiO₂-free and 20% TiO₂-containing PEEK. The PEEK dental crowns were fabricated and aging-treated at 134 °C and 0.2 MPa for 5 h in accordance with the ISO 13356 specification before being cemented on artificial tooth abutments. The fracture loads of all crown samples were measured under compression tests. Results demonstrated that adding TiO₂ enhanced the fracture load of PEEK crowns compared to TiO₂-free PEEK crowns before the aging treatment. However, the aging treatment decreased the fracture load of TiO₂-containing PEEK crowns while increasing the fracture load of TiO₂-free PEEK crowns. The fracture morphology of TiO₂-containing PEEK crowns revealed finer feather shapes than that of the TiO₂-free PEEK crowns. We concluded that adding TiO₂ increased the fracture load of PEEK crowns without aging treatment. Still, the aging treatment influenced the fracture load and microscopic fracture morphology of PEEK crowns, depending on the addition of TiO₂.