Journal of biomedical materials research. Part B, Applied biomaterials最新文献

This study evaluates the effect of varying resin composite thicknesses for sealing the screw-access hole of zirconia abutments on the fatigue mechanical behavior of a lithium disilicate cement-retained material. One hundred lithium disilicate discs (Ø = 10 mm, 1 mm thickness; IPS e.max CAD, Ivoclar AG) were prepared, alongside zirconia abutments (Ø = 10 mm, 3 mm thickness, 2.5 mm of screw-access hole diameter; IPS e.max ZirCAD MO, Ivoclar AG). The specimens were randomly assigned to five groups based on the thickness of sealing resin composite (Tetric N-Ceram Bulk fill, Ivoclar AG): Ctrl (only PTFE tape); PTFE tape +0.5 mm composite; PTFE tape +1.0 mm composite; PTFE tape +1.5 mm composite; and PTFE tape +2.0 mm composite. Surface treatments were conducted on ceramics before luting with dual-cure resin cement (Multilink N, Ivoclar AG). Monotonic testing was conducted at a loading rate of 1.0 mm/min until crack detection (n = 5). Cyclic fatigue testing was performed (n = 15; 100 N for 5000 cycles, followed by increments of 100 N every 10,000 cycles at 20 Hz) until failure. Finite element and Scanning Electron Microscopy analyses were also performed. One-way ANOVA and Tukey post hoc tests were used for monotonic data, while Kaplan–Meier and Mantel-Cox tests assessed survival rates (α = 0.05) based on fatigue test. No significant differences in monotonic tests were found. However, the 1.5 mm and 2.0 mm groups exhibited significantly higher fatigue failure loads compared to the Ctrl, 0.5 mm, and 1.0 mm groups (0.5 mm: 1093 N = Ctrl: 1120 N = 1.0 mm: 1127 N < 1.5 mm: 1426 N = 2.0 mm: 1307 N, p ≤ 0.05). To improve the fatigue behavior of lithium disilicate restorations bonded to zirconia abutments, more than half of the screw-access hole (greater than 1.5 mm) should be filled with resin composite.

In contemporary orthopedics, the demand for temporary biodegradable bone implants has driven the development of materials capable of supporting bone regeneration while gradually resorbing in the body, thereby eliminating the need for secondary removal surgery. Magnesium (Mg) and its alloys have emerged as promising candidates due to their bioactivity, osteoconductivity, and mechanical properties that closely match those of natural bone. Furthermore, the release of Mg²⁺ ions during degradation has been shown to stimulate osteoblast activity and enhance bone remodeling. Despite the advantages associated with Mg as a bone implant, there are also constraints on its clinical application. The elevated pH values inherent to the Mg corrosion process may adversely affect biocompatibility, in addition to general concerns about the burst release of H₂ gas that originates from the cathodic reaction of Mg corrosion. To address these challenges, biomimetic surface modifications have emerged as a promising strategy to modulate the degradation behavior of Mg and its alloys. In particular, Dulbecco's Modified Eagle Medium (DMEM) cell culture medium serves as an effective biomimetic environment for forming corrosion-resistant layers on Mg-based implants, maintaining physiological pH and mimicking in vivo degradation behavior by facilitating the formation of a carbonated Ca/Mg-phosphate layer with superior resistance to Cl⁻ attack compared to Mg(OH)₂. Immersion in DMEM has been shown to induce the formation of calcium phosphate rich protective layers that mimic the natural bone environment and mitigate the rapid biodegradation of Mg and its alloys. This paper provides a review of recent advancements in DMEM modification of Mg-based alloys, including ex situ and in situ formation of protective layers, and in vitro biocorrosion behavior in cell culture medium. Key findings emphasize that synthetic buffers like Tris/HCl and HEPES accelerate corrosion and hinder calcium phosphate formation, while protein-rich media risk contamination during prolonged use. Additionally, electrostatic interactions in DMEM promote hydroxyapatite crystallization, functionalized intermediate layers enhance calcium phosphate deposition, and fluid dynamics must be carefully controlled to stabilize the protective layer. Despite recent progress, key knowledge gaps remain, including limited understanding of the long-term performance and mechanical stability of biomimetic layers under dynamic physiological conditions, as well as the unclear impact of complex in vivo factors like immune responses and enzymatic activity on their degradation.

To compare the osseointegration properties of two different types of nitrogen-containing bisphosphonate (N-BP)-coated dental implants in an experimental in vivo sheep model. In total, eight sheep were divided into two groups receiving implants at two time points. Each animal received four types of implants, AddBIO STL implants coated with Zoledronate (Zol) and AddBIO STL implants coated with Ibandronate and Pamidronate (IbaPam) as test groups and uncoated AddBIO STL implants (UC) and Straumann original SLA implants (SSLA) as controls. Implants were placed in the metatarsus bilaterally, and healing times were either 10 or 28 days. Implant stability quotient (ISQ) was measured at baseline and at euthanasia. Removal torque (RT) was assessed post-mortem, followed by histomorphometric analysis to evaluate bone-to-implant contact (BIC) and bone area (BA). The differences between implants were evaluated using paired t-tests. The significance level was set at p value < 0.05 After 10 days, Zol implants presented significantly higher RT (Ncm mean ± SD) values 26.0 (± 18.0) than IbaPam implants 8.3 (± 14.9) (p = 0.011). SSLA implants demonstrated significantly higher RT values 34.6 (± 22.2) than Zol and IbaPam-coated implants (p = 0.048) and Zol-coated implants showed significantly higher RT values than UC implants 12.0 (± 7.6) than UC implants (p = 0.015). No significant differences in RT were detected at 28 days. No differences were observed among the groups regarding ISQ, BIC, or BA at either time point. Zoledronate-coated implants exhibited enhanced early mechanical stability compared to ibandronate/pamidronate-coated implants. However, this advantage was eradicated after 28 days, suggesting that the early anabolic effect of zoledronate may be time-limited.

The development of functional materials for osteoporosis is essential for effective bone remodeling. In this context, the extraction of biocompatible implantable biomaterials from bio-waste emerges as a valuable strategy, addressing both environmental challenges and promoting human health. The objective of this work was to evaluate the physicochemical properties of the added-value by-product biomaterial (SS-90), extracted from sardine scales (Sardina Pilchardus) and combined with chitosan (SS-90-CH). Besides, the efficacy of both biomaterials for bone regeneration was evaluated through in vitro and in vivo tests. The physicochemical characteristics of the biomaterials were demonstrated by ICP-OES, TGA, XRD, FTIR, and SEM-EDS analyses. Their characteristic features were compared with pure commercial hydroxyapatite (HA_syn) and associated with chitosan (HA_syn-CH). ICP-OES analysis evidenced the presence of Ca, P, Mg, Na, Sr, and Zn in SS-90 with a molar ratio (Ca/P) of 1.84 near to that of synthetic hydroxyapatite (1.67). The FTIR spectrum confirmed the presence of carbonate and phosphate functional groups in SS-90, which is similar to healthy rat bone (HRB). In vitro, SS-90 and SS-90-CH biomaterials demonstrated no cytotoxicity, maintaining cell viability between 80% and 100% for SaOS-2, L929, and LIG cells after 72 h of incubation. Furthermore, these biomaterials were implanted into bone defects in femoral condyles of osteoporotic rats to evaluate their effectiveness in bone fracture repair under osteoporotic conditions. Physicochemical, biochemical, and histological studies conducted at different time intervals after implantation indicated that the biomaterials could effectively promote bone regeneration. In conclusion, the present study highlights that SS-90 and SS-90-CH biomaterials are promising solutions for repairing bone defects or fractures under osteoporotic conditions, combining the valorization of marine bio-waste with biomedical applications.

Drug delivery to the central nervous system (CNS) is primarily hindered by the blood–brain barrier (BBB). To address this, mucoadhesive formulations have been designed to prolong residence time at the application site. In this study, we comprehensively characterized the physicochemical and mucoadhesive properties of hyaluronic acid tyramine (HATA) photocrosslinked hydrogels using rheological methods, nanoindentation, contact angle goniometry, and advanced confocal microscopy. A novel parameter, photon count per pixel, was introduced through confocal microscopy to assess hydrogel stability and mucoadhesion on ex vivo porcine olfactory tissues. Crosslinked hydrogels (1% and 2% w/v) exhibited stable mucoadhesive properties, ranging between 16.5 and 18 photon counts per pixel, whereas uncrosslinked counterparts typical of classical nasal formulations showed significant photon count losses (71% and 50% for 1% and 2% HATA, respectively). Nanoindentation analysis revealed a correlation between photoirradiation time, effective Young's modulus, and mucoadhesion, identifying 1 min of irradiation as optimal across all concentrations tested. The optimized hydrogels demonstrated mucoadhesive forces of 0.263, 0.412, and 0.701 mN mm⁻², corresponding to Young's modulus values of 1995, 2465, and 2985 Pa for 1%, 2%, and 3% w/v HATA, respectively. These results highlight the importance of crosslinking for enhancing hydrogel stability and mucoadhesion. Additionally, BSA-labeled rhodamine served as a model protein drug in low-swelling hydrogels for drug release studies, laying the foundation for further optimization in targeted nasal drug delivery systems.

Resin composites have become the preferred restorative material in modern dentistry due to their superior esthetics, improved physical properties, and advancements in curing technologies. To enhance their clinical performance, manufacturers continuously refine the resin matrix and optimize filler particle size and shape, improving both mechanical strength and optical characteristics. Evaluating optical properties is crucial for predicting the performance of resin composites over time, particularly in maintaining color, gloss, translucency, and overall appearance. Translucency refers to a material's ability to transmit and scatter light. This in vitro study evaluated changes in color, translucency, and gloss of nine commercially available flowable resin composites following artificial accelerated aging (AAA) and staining. Specimens were subjected to AAA and staining in black tea, coffee, and red wine. Using a spectrophotometer, color and translucency measurements were performed before and after the AAA and staining. Gloss measurements were performed using a small-area glossmeter before and after the AAA and staining. A two-way ANOVA was used to compare the effects of material and treatment, followed by Tukey's post hoc multiple comparison test to assess differences among levels within each variable (α = 0.05). A statistically significant interaction was observed between materials and procedures (p < 0.05) for color changes. All tested composites displayed translucency parameter changes within clinically acceptable limits. Gloss retention percentage upon treatments remained high across all composites tested. AAA and staining significantly influenced the color stability, translucency, and gloss retention of tested flowable resin composites, and were material- and procedure-dependent.