Does Melatonin Associated with Nanostructured Calcium Phosphate Improve Alveolar Bone Repair?

Effects of Photobiomodulation Using Low-Power Diode Laser Therapy and Nano-bone on Mandibular Bone Regeneration in Rats

Introduction: Recently, the positive effects of photobiomodulation (PBM) and nano-bone on bone regeneration have garnered significant attention. The purpose of the research was to assess the impact of PBM and nano-bone on the process of mandibular bone repair in mice. Methods: A 4-mm diameter bone defect was created in the left mandibular angle of 24 mice separated into 4 equal groups: group I: control; group II: PBM by irradiation at 100 mW of a 980 nm diode laser for one minute (three sessions per week; day on and day off); group III: nano-bone; group IV: PBM with nano-bone. Every group was sectioned into 3 equal subgroups corresponding to the evaluation method period: (A) one week, (B) two weeks, and (C) four weeks. Histological examination was done with hematoxylin, eosin, and Masson's Trichrome after one, two and four weeks for inflammation, bone defect coverage, vascularization within the newly formed bone, and new bone formation. Statistical analysis of the data was done and presented as percentage values using chi-square. The significance level was set at P value≤0.05 within all tests. Results: In general, by histological examination of the mandibular bone defect of the rats, the intensity of inflammation was the least in group IV when compared with groups II and III and the control group at all evaluation periods (P<0.001). Also, group IV showed a high significant rise in the percentage of new bone formation following four weeks when compared with the control (P≤ 0.001) and groups II and III (P<0.001). Conclusion: The present research results confirmed that the combination of PBM and nano-bone can aid in the repair of mandibular bone abnormalities. This animal study suggests that the use of PBM and nano-bone should be investigated further in clinical studies.

Melatonin-loaded mesoporous zinc- and gallium-doped hydroxyapatite nanoparticles to control infection and bone repair

Effective treatment of infected bone defects resulting from multi-drug resistant bacteria (MDR) has emerged as a significant clinical challenge, highlighting the pressing demand for potent antibacterial bone graft substitutes. Mesoporous nanoparticles have been introduced as a promising class of biomaterials offering significant properties for treating bone infections. Herein, we synthesize antibacterial mesoporous hydroxyapatite substituted with zinc and gallium (Zn-Ga:mHA) nanoparticles using a facile sol-gel method. The resulting mesoporous nanoparticles are applied for the controlled release of melatonin (Mel). Zn-Ga:mHA nanoparticles with an average particle size of 36 ± 3 nm and pore size of 10.6 ± 0.4 nm reveal a Mel loading efficiency of 58 ± 1%. Results show that 50% of Mel is released within 20 h and its long-term release is recorded up to 50 h. The Zn-Ga:mHA nanoparticles exhibit highly effective antibacterial performance as reflected by a 19 ± 1% and 8 ± 2% viability reduction in Escherichia coli and Staphylococcus bacteria, respectively. Noticeably, Mel-loaded Zn-Ga:mHA nanoparticles are also cytocompatible and stimulate in vitro osteogenic differentiation of human mesenchymal stem cells (hMSCs) without any osteoinductive factor. In vivo studies in a rabbit skull also show significant regeneration of bone during 14 days. In summary, Mel-loaded Zn-Ga:mHA nanoparticles provide great potential as an antibacterial and osteogenic component in bone substitutes like hydrogels, scaffolds, and coatings.

Innovative Biomaterials for Bone Tumor Treatment and Regeneration: Tackling Postoperative Challenges and Charting the Path Forward

Surgical resection of bone tumors is the primary approach employed in the treatment of bone cancer. Simultaneously, perioperative interventions, particularly postoperative adjuvant anticancer strategies, play a crucial role in achieving satisfactory therapeutic outcomes. However, the occurrence of postoperative bone tumor recurrence, metastasis, extensive bone defects, and infection are significant risks that can result in unfavorable prognoses or even treatment failure. In recent years, there has been significant progress in the development of biomaterials, leading to the emergence of new treatment options for bone tumor therapy and bone regeneration. This progress report aims to comprehensively analyze the strategic development of unique therapeutic biomaterials with inherent healing properties and bioactive capabilities for bone tissue regeneration. These composite biomaterials, classified into metallic, inorganic non-metallic, and organic types, are thoroughly investigated for their responses to external stimuli such as light or magnetic fields, internal interventions including chemotherapy or catalytic therapy, and combination therapy, as well as their role in bone regeneration. Additionally, an overview of self-healing materials for osteogenesis is provided and their potential applications in combating osteosarcoma and promoting bone formation are explored. Furthermore, the safety concerns of integrated materials and current limitations are addressed, while also discussing the challenges and future prospects.

Histomorphometric evaluation, SEM, and synchrotron analysis of the biological response of biodegradable and ceramic hydroxyapatite-based grafts: from the synthesis to the bed application

This study aimed to analyze the physicochemical and histological properties of nanostructured hydroxyapatite and alginate composites produced at different temperatures with and without sintering and implanted in rabbit tibiae. Hydroxyapatite-alginate (HA) microspheres (425-600 µm) produced at 90 and 5 °C without (HA90 and HA5) or with sintering at 1000 °C (HA90S and HA5S) were characterized and applied to evaluate thein vitrodegradation; also were implanted in bone defects on rabbit's tibiae (n= 12). The animals were randomly divided into five groups (blood clot, HA90S, HA5S, HA90, and HA5) and euthanized after 7 and 28 d. X-ray diffraction and Fourier-transform infrared analysis of the non-sintered biomaterials showed a lower crystallinity than sintered materials, being more degradablein vitroandin vivo. However, the sinterization of HA5 led to the apatite phase's decomposition into tricalcium phosphate. Histomorphometric analysis showed the highest (p< 0.01) bone density in the blood clot group, similar bone levels among HA90S, HA90, and HA5, and significantly less bone in the HA5S. HA90 and HA5 groups presented higher degradation and homogeneous distribution of the new bone formation onto the surface of biomaterial fragments, compared to HA90S, presenting bone only around intact microspheres (p< 0.01). The elemental distribution (scanning electron microscope and energy dispersive spectroscopy andμXRF-SR analysis) of Ca, P, and Zn in the newly formed bone is similar to the cortical bone, indicating bone maturity at 28 d. The synthesized biomaterials are biocompatible and osteoconductive. The heat treatment directly influenced the material's behavior, where non-sintered HA90 and HA5 showed higher degradation, allowing a better distribution of the new bone onto the surface of the biomaterial fragments compared to HA90S presenting the same level of new bone, but only on the surface of the intact microspheres, potentially reducing the bone-biomaterial interface.

Histopathological evaluation of the effect of melatonin gel on bone regeneration in rat model

Background

The purpose of this research was to investigate the effects of different doses of topical melatonin gel on bone regeneration in rat calvarial defects using histological analysis.

Materials and Methods

Fifteen adult female Wistar rats weighing approximately 200 g were used and 8 mm in diameter defects were created in their calvaria. The rats were divided into three groups: 1.2% melatonin gel, 5% melatonin gel, and the control group. The animals were sacrificed after 4 weeks. Hematoxylin and eosin staining were used to prepare histological sections. Statistical analysis was performed using the Analysis of variance and Tukey's post-hoc test. P < 0.05 was considered significant.

Results

The results showed a significant difference in rate of ossification (P < 0.001), area of new capillaries (P = 0.002), and mean degree of inflammation (P < 0.001) between the three groups. Comparing groups pairwise, degree of inflammation (P = 0.003) and area of new capillaries (P = 0.019) were significantly lower in the 5% melatonin gel group than the 1.2% melatonin gel group (P = 0.003). The percentage of ossification was substantially greater in the 5% melatonin gel group than in the control and 1.2% melatonin gel groups (P < 0.001).

Conclusion

Within the limitations of this animal study, our findings revealed that melatonin gel can be used as a stimulant of bone formation. Outcomes in this study show increased percentage of ossification in the melatonin groups when compared with the control, in a dose-dependent manner, as 5% melatonin gel has a greater effect on ossification.